NBSIR 76-1081

Progress Report on the

Corrosion Behavior of Selected

Stainless Steels in Soil

Environments

W. F. Gerhold, E. Escalante, and B. T. Sanderson

Corrosion and Electrodeposition Section

Metallurgy Division

Institute for Materials Research

National Bureau of Standards

Washington, D. C. 20234

August 1976

Progress Report

1970-1974

Prepared for

American Iron and Steel Institute

1000 16th Street, N. W.

Washington, D. C. 20036

NBSIR 76-1081

PROGRESS REPORT ON THE

CORROSION BEHAVIOR OF SELECTED

STAINLESS STEELS IN SOIL

ENVIRONMENTS

W. F. Gerhold, E. Escalante, and B. T. Sanderson

Corrosion and Electrodeposition Section

Metallurgy Division

Institute for Materials Research

National Bureau of Standards

Washington, D. C. 20234

August 1976

Progress Report

1970-1974

Prepared for

American Iron and Steel Institute

1000 16th Street, N. W.

Washington, D. C. 20036

/ v- j \

*

,

i—7 •

U.S. DEPARTMENT OF COMMERCE, Elliot L. Richardson, Secretary

Edward O. Vetter. Under Secretary

Dr. Betsy Ancker-Johnson, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acting Director

Progress Report on the Corrosion Behavior of

Selected Stainless Steels in Soil Environments

W. F. Gerhold, E. Escalante, B. T. Sanderson

Corrosion and Electrodeposition Section

Metallurgy Division

National Bureau of Standards

Washington, D. C. 20234

A. INTRODUCTION

Stainless steels* have been successfully used in limited applications

(such as for pipe clamps on cast-iron sewer lines) in soil environments for

many years. In recent years, other applications in use or under test include

ground rods, transformer cases, submerged switches, underground residential

distribution equipment, gas lines [1, 2], water lines, caskets, culverts,

residential sewage disposal systems, etc.

Corrosion data for selected annealed, unstressed austenitic and ferritic

stainless steels, buried in various soils, have been reported in NBS Circular

579 [3]. Tests conducted for 14 years in various soils in the United States

by NBS showed that austenitic Type 304 (containing Ni) and Type 316 (containing

Ni and Mo) stainless steels were highly resistant to both pitting corrosion

and general attack. Type 304 was susceptible to pitting corrosion in certain

highly aggressive soils, while Type 316 was relatively unaffected by corrosion.

The martensitic, Type 410 (12% Cr) and the ferritic Type 430 (17% Cr) stainless

steels were found to be fully resistant in only one-third of those soils where

they were exposed. Branch [1] and Steinmetz and Hoxie [2] have reported on

the suitability of stainless steels for some underground uses. Stress corrosion

cracking has not been reported to be a problem with Types 304 or 316 in actual

underground applications [1]. In a 2 year exposure to various soils in and

around Baltimore, Maryland, Type 304 gas service lines [50 for a total length

of 1 mile (1.61 km)] were reported to have suffered no corrosion effects [2].

In order to evaluate more fully the corrosion and stress corrosion

behavior of some of the different types of stainless steels considered for

use in soil environments, NBS in cooperation with the Committee of Stainless

Steel Producers, American Iron and Steel Institute, initiated in 1970 a soil

burial program in representative corrosive soils utilizing 9 stainless steels

in both the annealed and cold worked conditions with various treatments. Test

specimens incorporated welds, crevices, galvanic couples and specimens which

had been sensitized to induce carbide precipitation. In 1971 and in 1972, this

program was expanded to include additional stainless steels. The results

obtained for specimens buried in the soils for up to 2 years were reported in

1974 [4, 5], This report contains the results obtained for specimens buried

*The term "stainless steel" is broadly used in industry to describe any of a , number of different alloys of widely varying composition, corrosion resistance,

mechanical properties and microstructures. The essential alloying element

added to iron to form stainless steels is chromium, which is present from

10.5 - 30 percent. In some cases, additional alloying elements are used such

as nickel or molybdenum to enhance corrosion resistance.
I

at the NBS soil test sites for up to 4 years.

B. EXPERIMENTAL PROCEDURE

1. Soils at NBS Test Sites

Some of the properties of the soils at the NBS test sites are given in

Table 1. The relative corrosivity of these soils on plain carbon steel is

shown in Fig. 1. However, the corrosivity of these soils towards stainless

steels may not necessarily be the same as with carbon steel. Following are

detailed descriptions of the soils at the test sites which have been selected

by NBS from 128 test sites previously evaluated to represent the range of

soil properties having a bearing on the corrosivity of metals in soils.

Sagemoor Sandy Loam (Site A) is a well -drained alkaline soil with a resistivity of 400 ohm-cm and a pH of 8.8 and is typical of that found in

vast areas of eastern Washington and Oregon. The site is located on the

Yakima Indian Reservation near Toppenish, Washington. The soil is consistent

in composition to a depth of at least 7 feet (2.13 m) and supports an

abundant growth of sage-brush.

Hagerstown Loam (Site B) is a well -drained soil representative of the

majority of well -developed soils found in the eastern part of the United

States. The site is located at the Loch Raven Reservoir of the Baltimore

Water Department. The soil consists of a brown loam about 1 foot (0.30 m)

deep, underlain by reddish-brown clay that extends about 5 feet (1.52 m) or

more to underlying rock. The soil has a resistivity in the range of 12,600

to 37,300 ohm-cm and a pH of 5.3. Practically all of the materials that have

been investigated in the extensive NBS soil corrosion tests have been exposed

at this site which, therefore, can serve as a reference site for the correlation

of data obtained for specimens in the present program with data obtained from

the earlier tests.

Clay (Site C) is located in a large clay pit on level land at the U. S.

Coast Guard Receiving Center, Cape May, New Jersey, and is subject to

flooding during heavy rains. The soil consists of a plastic gray clay to a depth of 6 inches (15.24 cm) underlain by gray clay mixed with patches of

brown clay to a depth of 12 inches (30.48 cm). This is underlain by a poorly

drained very heavy plastic clay in which the specimens are exposed. The soil

has a resistivity which ranges from 400 to 1150 ohm-cm and a pH of 4.3.

Lakewood Sand (Site D) is a white, loose sand with some black streaks

occurring in places and supports an abundant growth of beach grasses. The

site is located in a well -drained rolling area on the property of the U. S.

Coast Guard Electronic Engineering Station, Wildwood, New Jersey. This

site is not subject to overflow from the ocean except under unusual flood

conditions. The sand has a pH of 5.7 and the resistivity ranges from 13,800

to 57,500 ohm-cm.

Coastal Sand (Site E )is a typical white, coastal beach sand with a high content of black sand; at this site, however, the sand is constantly

damp and is occasionally flooded with sea-water. The site is located on the

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i
Two-Mile Beach on the property of the U. S. Coast Guard Electronic Engineering

Station, Wildwood, New Jersey. The sand has a pH of 7.1, and the resistivity

ranges from 1,320 to 49,500 ohm-cm.

Tidal Marsh (Site G) is a soil typical of the poorly-drained marsh soils

that are found along the Atlantic and Gulf coasts. The site is located along

a creek (Pine Hill Run) that empties into the Chesapeake Bay at the Patuxent

Naval Air Station, Lexington Park, Maryland. The soil is naturally charged

with hydrogen sulfide and has a resistivity in the range from 400 to 15,500

ohm-cm and a pH of 6.0.

2. Materials, Treatment and Preparation

In order to simulate some of the conditions that may be encountered with

components fabricated from stainless steels, materials for these soil corrosion

studies included stressed and unstressed flat sheet specimens with and without

welds, welded tube specimens, coated specimens, sensitized specimens, and

stressed and unstressed galvanically coupled specimens.

Descriptions of the various stainless steel systems buried at each test

site including treatments and preparation are given in Table 2. The chemical

analyses and mechanical properties of each alloy are given in Tables 3 and 4.

Upon receipt of the specimens from the stainless steel producers, the

specimens were first stamped with identification numbers using chromium plated

steel dies. All of the flat sheet materials [approximately 0.06 inch (0.15 cm)

thick] were supplied with sheared edges which had been deburred. In some

instances further deburring was necessary. All of the materials to be exposed

unstressed were then degreased in trichlorethylene vapor, passivated (using

procedures described in Table 2), scrubbed with a fiber brush, thoroughly rinsed

with water and then air dried.

Half of the coated [coal-tar epoxy, 16 mils (0.04 cm) per side] specimens

(System No. 61) were scored diagonally from the corners, twice on one surface,

by cutting through the coating to the base material with a sharp pointed

instrument. The other half of the specimens were exposed in the "as coated"

condition.

The cross-bead welded flat sheet materials (System Nos. 3, 9, 11 and

54) were prepared in accordance with Welding Research Council recommendations.

Type 304 tube (System No. 57) was prepared in accordance with ASTM

Specification A249. Type 409 tube (System Nos. 62 and 63) was tested in

the "as-welded" condition. Except for cleaning and passivating, the proprietary

alloys were tested as supplied by the producers. The ends of the tube specimens

were plugged with rubber stoppers and then plastic or rubber caps were placed

on each end to create a crevice.

All of the sheet materials to be stressed as either single or double

U-bends had oblong holes, 1/4 inch x 1/2 inch (0.64 cm x 1.27 cm), punched

near each end so as to be self aligning after bending. Specimens to be connected

to a dissimilar metal (galvanic couples) had an additional hole 0.093 inch

(0.236 cm) drilled 1/4 inch (0.64 cm) from the end and side for wire connections.

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The specimens to be stressed were initially bent using a die (shown in

Fig. 2) to about 20° (internal angle). The only portions of the die in

contact with the specimens during the forming operation were fabricated from

Type 304 stainless steel. The specimens were then cleaned and passivated

using the same procedures noted above for unstressed specimens.

Single U-bend specimens were then formed by bending the two ends in a wooden jig so that they were parallel [the inside diameter at the bend was

approximately 1 inch (2.54 cm)] and clamping them in this position with a Type

316 stainless steel nut and bolt. Double U-bend specimens for crevice and

stress corrosion studies were formed in the same manner except that some were

spot welded together (see Fig. 3) prior to the bending operation. They were

then bent at the same time to form the U and clamped at the ends with Type 316

stainless steel fasteners.

For the galvanic couple studies, specimens were connected to steel (iron),

zinc or magnesium anodes or to copper strips. Connection was made by soldering

14 gauge stranded copper wire to the specimen at the drilled hole using 50-50

acid core solder.

The iron anode consisted of a 1 foot (0.3 m) length of a cold finished

steel (AISI 1017-1018) 3/4 inch (1.90 cm) hexagonal shaped rod with a hole

[0.093 inch (0.236 cm)] drilled in the rod mid-way between each end for the

electrical connection. The copper wire from the specimen was inserted in

this hole and then soldered to the iron anode using 50-50 acid core solder.

The magnesium anode [4 feet (1.2 m) long and bent in the form of a horseshoe] was of the commercial flexible extruded type with an oval shaped

cross-section 3/4 inch x 3/8 inch (1.90 cm x 0.95 cm) and a continuous centrally

located 1/8 inch (0.32 cm) diameter iron wire core. The copper wire from the

specimen was soldered to a 1 inch (2.54 cm) extension of the iron wire core using

50-50 acid core solder. In addition a bituminous (coal-tar epoxy) coating was

applied to both 3/4 inch (1.90 cm) faces of the anode to extend its effective

life.

The zinc anode [1 foot (0.30 m) long] was also of the commercial flexible

extruded type with a diamond shaped cross section [5/8 inch x 7/8 inch (1.59

cm x 2.22 cm)] and a continuous centrally located 0.1 inch (0.25 cm) diameter

zinc-coated (galvanized) iron wire core. The stranded copper wire from the

specimen was soldered to an extension of the galvanized wire core.

Copper strips which were electrically coupled to the unstressed stainless

steel specimens were cut from cold-rolled copper sheet, 0.065 inch (1.651 cm)

thick and of the same dimensions as the stainless steel specimen [1 inch x 12

inches (2.54 cm x 30.48 cm)].

The areas at all soldered joints, including any exposed portions of the

copper wire, were covered with a bituminous (coal-tar epoxy) coating.

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3. Exposure

At each test site, the specimens were buried in trenches approximately

2-1/2 feet (0.76 m) deep and 2 feet (0.61 m) wide. The specimens were placed

about 1 foot (0.30 m) apart. The 8 inch x 12 inch (20.32 cm x 30.48 cm) sheets

were placed in the trench in a vertical position (with the long dimension

horizontal). The specimens electrically connected to the steel and zinc anodes

and to the copper strips were placed in the trench with the dissimilar metal

parallel to the specimen and separated by approximately 1 foot (0.30 m).

Specimens electrically connected to the horseshoe shaped magnesium anodes were

placed at the center of the horseshoe. Upon backfilling the trenches, the

insulated wires soldered to those specimens to be used in potential and corrosion

current (couple corrosion) determinations were connected above ground to terminal

strips mounted on 4 inch x 4 inch x 6 foot (10.16 cm x 10.16 cm x 1.83 m) wooden

posts. Leads from the anodes and copper strips were connected to leads from

the specimens at the terminal strips (potential and current measurements).

Sufficient specimens were buried at each of the 6 test sites to permit

recovery of a complete set at specified intervals (1, 2, 4 and 8 years) and

a final set to be removed at a later date to be determined. Each set of the 8

inch x 12 inch (20.32 cm x 30.48 cm) flat sheet systems and welded tube systems

consisted of 4 specimens, while for the stressed and unstressed 1 inch x 12 inch

(0.254 cm x 30.48 cm) sheet systems, each set consisted of 2 specimens.

The burial order for each test site is shown in Figs. 4a, b and c. One

thousand fifty four (1054) specimens were buried at each test site for a total

of 6324 specimens at the six test sites.

4. Electrochemical Measurements

All electrochemical measurements (potential, couple current, and

corrosion current) were made at time of burial and subsequently 3 times a year

when possible with the exception of Site A where measurements were usually

made once a year.

Electrochemical potentials of the specimens and couples v_s. a Cu-CuS04

half cell were measured using a high precision portable pH meter as a mi Hi voltmeter. The half cell was placed in a remote area (usually at the

edge of the test area) and shielded from light to prevent photochemical

effects.

The couple currents of the anode systems and the stainless steel-copper

systems were measured using a zero impedance circuit employing an operational

amplifier (Fig. 5) for small currents and a commercially available zero

resistance ammeter for larger currents.

Corrosion currents were measured using a modification of the linear

polarization technique based on the following relationship derived by Stern

and Geary [5]:

Al

2.31 I corr

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where AE is the overvoltage of the corroding specimen produced by a polarizing

current, Al. Ba and Bg are the slopes of the anodic and cathodic polarization

curves, respectively, in the Tafel region and I corr is the corrosion current.

Assuming Ba and Bc equal to 0.1 V in this investigation (the error will usually

be about 20% or less, as established by Stern and Weisert [6],) the following

equation was derived:

I orr(mA) = 2.7AI (mA)

corr

AE (If

The electrical circuit described previously, [7] but minus the bridge

circuit was employed. A soil auger was utilized as the auxiliary electrode.

The change in potential was measured directly using the pH meter or an

electrometer (0-10 mV scale) plus a battery and variable resistor (to null the

initial potential) and a CU-CUSO4 reference electrode. Electrodes (auxiliary

and reference) were placed so that the specimen was between them or at

approximately right angles to them. In making these measurements, an increment

of current was applied to the specimen unitl a stable overpotential of usually

2 to 10 mV occurred. The potential and current readings were then recorded.

Occasionally the open circuit potential of the stainless steel alloy was

found to fluctuate and the corrosion current measurements could not be made.

At other times, extremely humid or rainy conditions prevented these measurements.

5. Examination of Specimens After Exposure

Upon removal from the trench after burial for 1, 2 or 4 years, each of

the stressed specimens was examined for indications of failure by cracking.

All specimens were then returned to the laboratory for cleaning and a more

thorough examination.

In the laboratory, the specimens were rinsed in tap water to remove

adhering soil particles. They were then examined visually prior to further

cleaning. The stressed U-bend specimens were disassembled by removing the

Type 316 stainless steel fasteners. The copper wires were unsoldered from

those specimens that had been coupled to dissimilar metals.

All specimens, except the coated ones (System No. 61) and the composites

(System Nos. 14, 15 and 16), were then further cleaned ul trasonically using a 10% nitric acid solution heated to 120° - 130°F (49° - 54°C) for 20 to 30

minutes. Specimens from System Nos. 14 and 16 were ul trasonically cleaned using

an aqueous 10% ammonium citrate solution heated to 175° to 185°F (73° - 85°C).

The time for cleaning these specimens varied and was dependent upon the tenacity

of the corrosion scale. The specimens from System No. 15 were ul trasonically

cleaned for approximately 30 minutes using an aqueous ammonium chloride

solution at 175° to 185°F (79° - 85°C). After cleaning, the specimens were

rinsed in hot tap water and then air dried.

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The unstressed sheet [8 inches x 12 inches (20.32 cm x 30.48 cm)] and

tube specimens were then weighed twice and their weight loss was determined.

The average loss in weight of similar unexposed (control) specimens given

the identical cleaning process was subtracted from the weight loss of the

exposed specimens.

Pit depth determinations were obtained for all of the unstressed tube

and 8 inch x 12 inch (20.32 cm x 30.48 cm) sheet specimens.

C. RESULTS AND DISCUSSION

Table 5 summarizes the results obtained from visual examination of

the unstressed non-welded sheet materials. The results obtained for welded

sheet and tube materials are summarized in Table 6. The results obtained

from average weight loss and pit depth determinations are given in Tables 7

through 12 and are shown graphically in Figs. 6 through 10.

Data given for each alloy system are a compilation of results obtained

from either 2 or 4 specimens depending upon the number of specimens of each

system that was exposed. The weight loss for a given alloy system exposed in

a particular soil may appear to be extremely small in comparison to the

observed corrosion. This occurs because the corrosion of stainless steels in

some environments can often be localized and confined to a very small area.

Similarly, one specimen may have only one corrosion pit which caused

perforation of the specimen, while there was little or no corrosion observed

on companion specimens exposed for the same period of time in the same

environment.

Corrosion of stainless steels is generally attributed to a breakdown

of the passive film at the surface of the material at localized or selective

areas. If corrosion occurs it may often be influenced by one or more of the

fol lowing:

1. Inhomogenei ties of the metal surface.

2. Concentration cell effects due to adhering soil particles or crevices

where stagnant conditions may exist.

3. Presence of chlorides in the soil.

4. Microbiological organisms.

5. Abrasion of the metal surface by soil particles or foreign

debris.

A break in the passive film at the localized area results in a small

anodic site. The larger surrounding area is the cathode. The electrolytic

cell formed could result in localized pitting corrosion, which can rapidly

penetrate the thickness of the metal. However, a stainless steel with

adequate alloying content for the environment would repassivate without

degradation. Concentration cells formed at stagnant areas beneath soil

deposits or at crevice areas can also result in localized corrosion. An

unusual form of pitting corrosion, tunneling, is normally associated with

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edges and can be increased by gravity flow of corrosion products. As noted

above, all flat specimens were buried vertically, thus increasing the

propensity for tunneling.

1. General Corrosion Behavior

AISI 200 Series

Annealed Type 201 and 202 austenitic stainless steels (System Nos. 50

and 51) buried up to 4 years in alkaline soil (Site A), Hagerstown loam (Site

B) and dry sand (Site D) were in general unaffected by corrosion. However,

pitting corrosion was noted at the edge of one Type 201 specimen buried

for 2 years at Site D. Specimens of both systems buried in the acid clay

(Site C) and wet sand (Site E) exhibited pitting and tunneling corrosion and

were perforated due to corrosion after exposure for 1 year. Of the specimens

buried in the tidal marsh (Site G), both systems were susceptible to pitting

corrosion. Tunneling corrosion was also observed at the edge of one Type 201

specimen which had been buried for 4 years. A companion specimen buried at

this site for 2 years was perforated due to corrosion. Tunneling corrosion was

not observed on the Type 202 specimens. However, one specimen was perforated

at the edge due to pitting corrosion.

AISI 300 Series

Annealed Materials - In general, corrosion was nil or superficial for

the annealed austenitic 300 series materials buried for up to 4 years at Sites

A, B and D. Annealed Type 316 buried at Sites C and G was with a few exceptions

unaffected by corrosion. However, a few corrosion pits were observed at edge

areas on two specimens that were buried for 4 years at Site C. At Sites C and

G annealed Types 301 and 304 specimens were susceptible to pitting and tunneling

corrosion. All of the annealed 300 Series alloys buried at Site E exhibited

both tunneling and pitting corrosion and many specimens were perforated at

corroded areas.

Sensitized Materials - Degradation of the sensitized 300 series alloys

buried at Sites A and B for up to 4 years was nil or negligible.** However,

some slight etching and pitting corrosion was noted at areas on some specimens

buried at these sites. Of the sensitized materials buried at Site C, all were

susceptible to pitting corrosion with Type 316 being the least susceptible.

Sensitized Type 304 and Type 316 buried at this site were also susceptible to

tunneling corrosion. Some of the sensitized Type 301 and Type 304 specimens

buried at Sites D and E exhibited "blister-like eruptions" at surface areas.

These appeared to be very small corrosion pits.

Degradation of sensitized Type 301 and 304 specimens buried at Site G

was generally due to severe etching and non-uniform attack (Fig. 11).

Some specimens were perforated at scattered localized areas after burial of

1 or 2 years, but none had perforated after burial for 4 years. Corrosion of

Type 316 (sensitized) buried at this site was in general negligible.

Many of the specimens examined exhibited incipient pitting and various forms

of discoloration, e.g., iridescence, rust and dark to black stains. However,

no other degradation was observed on these specimens nor was there any loss

in weight due to exposure in the soil environment. Corrosion of these specimens

was considered to be nil or superficial.

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Welded Materials - Corrosion of the cross-bead welded Type 301 sheet and

heli arc-welded Type 304 tube specimens buried at Sites A, B and D was in

general nil or superficial. Pitting corrosion was noted at and adjacent to

the weld bead on the cross-bead welded Type 301 sheet specimens buried at

Sites C, E and G. Pitting corrosion was also observed at and adjacent to the

weld seam of Type 304 tube specimens buried at Site C and at areas adjacent to

the caps and at crevice areas (under the end caps) on tube specimens buried at

Sites C and E. However, pitting was also noted at areas remote from the weld.

It was not determined whether the welding operation resulted in sensitization

at the weld or whether the pitting corrosion was or was not due to

sensitization.

Figs. 12 through 15 are examples of some of the degradation noted on the

300 series specimens.

AISI 400 Series

Materials in this series include the martensitic Type 410 and ferritic

Types 409, 430 and 434 stainless steels.

Specimens of Type 409 (annealed or welded) and Type 410 (annealed) were

perforated by corrosion after burial for 4 years in 5 of the 6 soils. The

time to first perforation (generally 1 or 2 years) for the Type 409 materials

was less for specimens buried at Sites C, E and G. Corrosion of these alloys

was nil or superficial at Site B. The coal-tar epoxy coated Type 409 sheet

specimens were in general relatively unaffected by corrosion.

Types 430 and 434 were relatively unaffected by corrosion after burial

for 4 years at Sites A and B. Companion specimens buried at Sites C, E

and G were perforated by corrosion generally in less than 1 year. At Site

D first perforation for these materials was not observed until specimens had

been buried for 4 years.

Figs. 16 through 23 are examples of some of the degradation noted on 400

series specimens.

Specialty and Developmental Alloys

Stainless steels in this classification include proprietary and

composite materials. The proprietary stainless steels may be grouped as

follows according to major alloying constituents:

1 . Cr Stainless Steel

26 Cr - 1 Mo

18 Cr - 2 Mo

18 Cr - 2 Mo (Nb)

18 Cr (Ti)

2. Cr-Ni Stainless Steels

26 Cr - 6.5 Ni

20 Cr - 24 Ni - 6.5 Mo

18 Cr - 8 Ni (N) (Now designated as AISI Type 304 N)

-9-
The results obtained from visual examination of specimens of these

materials after burial in the various soils for up to 3 years are

summarized in Tables 5 and 6.

Cr Stainless Steels - Alloy 26 Cr-1 Mo [in the annealed condition

(System No. 1)J was relatively unaffected by corrosion in any of the soils

after burial for up to approximately 3 years. Pitting corrosion was noted

particularly at or adjacent to crevice and weld areas of some of the heliarc

welded Alloy 26 Cr-1 Mo specimens (System No. 17) buried at Sites A, C, E and

G.

Corrosion of annealed Alloy 18 Cr-2 Mo (System No. 6) was nil or superficial for specimens buried for up to 3 years at Sites A, B, C and D.

Scattered pitting corrosion with subsequent perforation of the material

was observed on specimens buried at Sites E and G. Corrosion of annealed

Alloy 18 Cr-2 Mo (Nb) (System No. 7) specimens was in general nil or superficial after burial for up to 2 years. Pitting corrosion was noted at weld

areas of cross-bead welded sheet specimens (System No. 11) buried at Sites

C, E and G and tube specimens (System 12) buried at Sites A and E. Pitting

corrosion was also observed at crevice areas of tube specimens buried at

Sites E and G. Specimens of System 11 were perforated due to corrosion at

Sites C and E.

Of the Alloy 18 Cr (Ti ) (System Nos. 2, 3 and 18) specimens buried

for up to 3 years, corrosion of those buried at Sites A, B and D was in

general nil or superficial. Some specimens buried at Sites C, E and G were

perforated due to corrosion.

Cr-Ni Stainless Steel - The annealed Alloy 18 Cr-8 Ni (N) (System No.

8) specimens were in general relatively unaffected by corrosion after burial

for approximately 3 years at Sites A, B, C and D. Some specimens buried at

Sites E and G were perforated due to corrosion. Sheet specimens of this

alloy having a cross-bead weld (System No. 9) and buried at Sites C, E and

G were perforated due to pitting corrosion at weld areas. There was little

or no corrosion of companion specimens buried at Sites A, B and D.

There was little or no appreciable attack on the annealed (System No. 4),

sensitized (System No. 5) or heliarc welded (System No. 19) Alloy 20 Cr-24 Ni6.5 Mo specimens buried in the 6 soils. Corrosion where observed was in

general superficial.

Corrosion of annealed Alloy 26 Cr-6.5 Ni (System 10) specimens buried

at Sites A, B and D was in general negligible. Companion specimens of this

alloy buried at Sites C, E and G were perforated by corrosion in less than 1 year.

Composite Materials - The composite systems are sandwich materials where

outer layers of carbon steel are metal! urgically bonded to a thin core of

stainless steel (total thickness approximately 0.120 in (0.305 cm). Composites

A and B (System Nos. 14 and 15) were fabricated with Type 430 stainless steel

as a core material while Composite C (System No. 16) utilizes Type 304

stainless steel. In addition Composite B specimens were individually hot-dip

zinc coated [galvanized, 4.5 to 5 oz/ft2(1377 to 1528 gms/m2

) zinc]. This

was a thicker coating than would normally be used on carbon steel products.

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In general, there was little difference in the corrosion behavior of

System Nos. 14 and 16 buried in the same soil environment for approximately

4 years. Pitting corrosion of the carbon steel outer layers was observed

on all specimens buried at the six sites. The carbon steel was perforated

by corrosion on specimens buried at Sites A, B and G which thus exposed the

stainless steel core of both composite materials. While there was no apparent

significant corrosion of the stainless steel core of these specimens,

degradation of the carbon steel was more severe for specimens buried at Site G.

The hot-dip zinc coating on specimens of System No. 16 provided protection

to the underlying carbon steel and stainless steel core in all of the soils.

There was some dissipation of the zinc in all of the soils. However, there

was some zinc remaining on all of the specimens after burial for up to 4 years

in the 6 soil environments.

2. Stress Corrosion Behavior

The results of visual and micro examinations made to determine failure

of the various systems due to stress corrosion cracking are given in Table 13

for non-galvanically coupled specimens.

AISI 300 Series

Type 301 stainless steel in the half-hard condition was relatively

immune to stress corrosion cracking in all of the soils after exposure for

approximately 4 years. Micro-cracking was observed on one specimen buried

for 2 years at Site C. Sensitization of the half-hard alloy increased the

susceptibility to stress corrosion cracking in all of the soil environments.

Of the specimens buried for 4 years, all exposed at Sites A, C, D, E and G

had failed, while at Site B, only 1 of the 2 specimens retrieved was cracked.

The same alloy in the full -hard condition was in general also immune to stress

corrosion cracking after exposure for up to 4 years. However, micro-cracking

was noted on one of the spot welded specimens buried for 2 years at Site G.

No failures were observed on stressed Type 304 in the annealed or half-hard

condition. Cracking of the sensitized Type 304 stressed specimens in the half

hard condition, buried at Site C for 2 years and Site E for 1 year, was observed

while companion specimens buried for 4 years at these sites were unaffected

by cracking.

AISI 400 Series

Type 434 stainless steel was the only alloy in this series exposed in

the soils. There were no failures after burial for 4 years in any of the

soils.

Specialty and Developmental Alloys

Steels in this category included Alloys 26 Cr-1 Mo, 18 Cr-2 Mo, 20 Cr-24

Ni -6.5 Mo, 18 Cr-8 Ni (N) and 26 Cr-6.5 Ni. There were no failures of these

steels after exposure for up to 3 years.

-11-
3. Stressed Dissimilar Metal Couples

The results for the stressed galvanically coupled specimens have been

reported elsewhere [6], Table 14 in this report summarizes the results

obtained for specimens buried for approximately 4 years.

AISI 300 Series

There were no failures noted for Type 304 in the annealed condition

when coupled to zinc, magnesium or iron. Type 301 full -hard and Type 301

half-hard have a tendency to stress crack. As shown in Table 14 all of the

stressed Type 301 full -hard stainless steel specimens and all but 1 of

the Type 301 half-hard specimens coupled to magnesium failed in the four

years of exposure. When coupled to iron, these materials were resistant to

cracking at 4 of the 6 sites (Sites A, B, D and E). One Type 301 full-hard

specimen buried at Site G had failed while Type 301 half hard specimens buried

at this site had not failed. Both materials when coupled to zinc had failed

at all of the sites except for those buried at Site A. The largest currents

were generated by magnesium followed by zinc and iron. It was noted that

below 1 yA/cm^ no failures occurred for the Type 301 materials. As the current

density increased to above 8 yA/cm^ all Type 301 full -hard specimens failed

and above 20 yA/cm all Type 301 half-hard specimens failed. The fact that

the number of failures increased with increasing cathodic current indicates

that hydrogen embrittlement was the mode of failure.

Specialty and Developmental Alloys

There were no failures of the 26 Cr-1 Mo or 26 Cr-6.5 Ni galvanically

coupled to zinc, magnesium or iron after exposure for approximately 3 years in

the soils.

4. Unstressed Dissimilar Metal Couples

The results obtained for unstressed stainless steels coupled to a dissimilar metal (copper) have been reported elsewhere [7]. Table 15 in this

report summarizes the results obtained for these stainless steels, each

coupled to copper, after burial for up to 4 years in the various soil

environments. The data shows that where the galvanic current was negative,

little or no corrosion occurred. The only exception was on Alloy 26 Cr-6.5 Ni

material exposed at Site E where pitting corrosion was noted on specimens at

areas under the solder. This corrosion suggests that the solder connection

was poor resulting in an inaccurate current determination for the specimens.

The Type 409 stainless steel was the most severely corroded. However, there

was no clear indication that the copper adversely affected the stainless

steel. The results obtained from visual examination of the copper electrodes

are given in Table 16. Since the copper was coupled to stainless steel, the

electrochemical tabulations given in Table 15 also apply to the copper. It

was noted that as the potential of the galvanic couple became more noble (more

positive), the corrosion of the copper increased. The galvanic potentials at

Site B were around zero (vs. Cu-Cu S0^ reference electrode) and caused the

most corrosion observed on the copper. The corrosion of the copper was least

at Site G.

-12-
D. SUMMARY

1. AISI 200 and 300 Series

In general all of the austenitic (200 and 300 series) stainless steels

included in this program exhibited good resistance to corrosion after burial

for up to approximately 4 years in alkaline soil (Site A), Hagerstown loam

(Site B) and Lakewood sand (Site D). These stainless steels were susceptible

to corrosion in the acid clay (Site C), coastal sand (Site E) and tidal marsh

(Site G). Type 316 (annealed) was the least susceptible to corrosion in the 6

soils investigated. Degradation of the 200 and 300 series stainless steels

was generally due to pitting or tunneling corrosion or a combination of both

with subsequent perforation of the specimens at localized areas. For some

specimens buried in the tidal marsh, corrosion was observed at large areas on

the specimens and was attributed to severe etching or general corrosion of the

metal surfaces. Sensitization by heat treatment of Types 301, 304 and 316

generally resulted in increased susceptibility to corrosion in all of the

soils.

Pitting corrosion was observed at or adjacent to the weld beads on

cross-bead welded Type 301 sheet specimens buried at Sites C, E and G and at

or adjacent to the weld seams on Type 304 tube specimens buried at Sites A, C

and G. It must be stressed that pitting also occurred at other areas on the

specimens remote from the welds. It was not determined at this time whether

the welding operation resulted in sensitization at the weld areas or whether

the pitting corrosion observed was or was not due to sensitization. Future

studies will examine these questions. Type 304 tube specimens buried at Sites

C and G were also susceptible to crevice corrosion.

With some exceptions the non-galvanic couples stressed 300 series alloys

exhibited good resistance to stress corrosion cracking in all of the soils.

Type 316 in the annealed or sensitized condition was immune to stress corrosion

cracking in all of the soils after exposure for 4 years. Type 301 in the halfhard condition was susceptible to cracking at Site C, while spot-welded Type

301 in the full-hard condition was susceptible to cracking at Site G. Sensitization

of Type 301 half-hard increased the susceptibility to stress corrosion cracking

in all of the soils. Type 304 (annealed) was immune to stress corrosion, but

sensitization of this material made the alloy susceptible to stress corrosion

at Sites C and E.

Galvanic coupling of Type 301 half-hard or full-hard stainless

steel to magnesium or zinc increased the susceptibility to stress-cracking.

When coupled to zinc, failures were observed in five of the six soils (exception

was Site A) while, when coupled to magnesium, failures were observed in all

of the soils. This alloy in the half-hard condition and coupled to iron

failed at Site C only, while similar specimens in the full-hard condition

failed at Sites C and G.

2. AISI 400 Series

The martensitic Type 410 and the ferritic Types 409, 430 and 434 stainless

steels were in general susceptible to pitting or tunneling corrosion or a

-13-
combination of both at Sites A, C, D and E and to severe etching or general

corrosion attack at Site 6. Except for the Type 430 and Type 434 buried at

Site A, all were perforated due to corrosion. Of these materials buried for

4 years at Site B, the corrosion observed was nil or superficial. Areas at

and adjacent to the weld seam on the heliarc welded Type 409 specimens buried

at Sites C and G and the high-frequency welded Type 409 specimens buried at

Sites A, C, D, E and G were susceptible to pitting corrosion. Pitting corrosion was also observed at crevice areas on these two materials buried at

all sites except Site B. The coal-tar epoxy coating applied to the Type 409

stainless steel appeared to be effective in providing protection from corrosion

at all sites. However, some superficial corrosion was noted at areas where

the coating had been scored to bare metal prior to burial.

Type 434 was the only stainless steel in the 400 series included in the

stress corrosion study. No failures were observed for non-gal vanical ly

coupled stressed specimens of this material in any of the soil environments.

3. Specialty and Developmental Stainless Steels

Annealed and hel iarc-welded Alloy 20 Cr-24 Ni-6.5 Mo was resistant to

corrosion in all of the soils after burial for 3 years. Sensitized specimens

of this material were resistant to corrosion in all of the soils except at

Sites C and G.

Annealed 26 Cr-1 Mo stainless steel was slightly pitted (< 5 mils deep)

due to corrosion at Site C only after burial for 3 years. However, heliarcwelded tube was susceptible to crevice corrosion and/or pitting at Sites A,

C, E and G. This alloy was not exposed in the sensitized condition.

Alloy 18 Cr-2 Mo (Nb) in the annealed condition and buried for 3 years

was resistant to corrosion at Sites B and D. Also after exposure for 3 years,

cross-bead welded sheet specimens of this alloy were unaffected by corrosion

at Sites A, B and D. Heliarc welded tube specimens, exposed for 2 years, were

resistant to corrosion at Sites B, D and G.

Annealed 18 Cr-2 Mo stainless steel was resistant to corrosion during

a 3 year period at Sites A, B and D but was susceptible to pitting corrosion

at Sites C, E and G.

Annealed and cross-bead welded 18 Cr-8 Ni (N) (now designated AISI Type

304 N) stainless steel specimens exposed for 3 years were also resistant to

corrosion at Sites A, B and D and were similarly susceptible to pitting corrosion at Sites C, E and G.

Alloy 26 Cr-6.5 Ni in the annealed condition was resistant to corrosion

at Sites B and D but was susceptible to pitting corrosion at Sites A, C, E and

G.

Annealed 18 Cr (Ti ) sheet and heliarc welded tube stainless steel specimens were resistant to corrosion at Sites A and B. The heliarc welded tube

was also resistant to corrosion at Site D, but the annealed sheet material

at this site was pitted due to corrosion. Both types of specimens of this alloy

were severely corroded at Sites C, E and G.

-14-
Of the proprietary steels included in the stress corrosion study, there

were no failures of either galvanically coupled or non-galvanically coupled

specimens after 4 years exposure in any of the soils.

ACKNOWLEDGEMENTS

The assistance of James L. Fink in various capacities during this

investigation is acknowledged.

Acknowledgement is made also to the following organizations which

provided test sites and assistance during the burial and removal of the

specimens and during the inspections at the test sites.

Bonneville Power Administration

U. S. Department of Interior

Portland, Oregon 97208

Baltimore Bureau of Water Supply

Baltimore, Maryland 21217

U. S. Coast Guard Training Center

Cape May, New Jersey 08204

Patuxent Naval Air Station

Lexington Park, Maryland 20653

U. S. Coast Guard Electronics Engineering Station

Wildwood, New Jersey 08260
REFERENCES

[1], Branch, H. C, Corrosion Resistant Materials for URD Equipment, Materials

Protection and Performance , 12., 9-14 (March 1973).

[2], Steinmetz, G. F. and Hoxie, E. C, A Field Test of Type 304 Stainless

Steel for Gas Service, Materials Protection and Performance , 12 , 41-44

(September 1973).

[3]. Romanoff, M., Underground Corrosion (NBS Circular 579), National Technical

Information Service, PB 168350 (April 1957).

[4]. Gerhold, W. F., Iverson, W. P., Escalante, E. and Sanderson, B. T., Progress

Report on the Corrosion and Stress Corrosion of Stainless Steels in Soil

Environments, Part I. General Corrosion (NBS Report, NBSIR 74-483),

(May 1974).

[5], Gerhold, W. F., Escalante E., Iverson, W. P. and Sanderson, B. T., Progress

Report on the Corrosion and Stress Corrosion Behavior of Selected Stainless

Steels in Soil Environments, Part II. Stress Corrosion and Electrochemical

Behavior (NBS Report, NBSIR 74-484), (May 1974).

[6], Escalante, E. and Gerhold, W. F., "Galvanic Coupling of Some Stressed

Stainless Steels to Dissimilar Metals Underground", Galvanic and Pitting

- Field and Laboratory Studies, ASTM STP 576, American Society for Testing

and Materials, pp. 81-93 (1976).

[7]. Escalante, E. and Gerhold, W. F., The Galvanic Coupling of Some Stainless

Steels to Copper - Underground, Materials Performance, 14, 16-20 (October 1975

-16-
0 2

Exposure Time, Years

Fig. 1. Relative Corrosion Effects of the Soils at the Six NBS Test Sites on

Carbon Steel

.
Fig. 2. Die for forming U-bend specimens.
5V

-3

8

Spot Weld

Fig. 3. Double or crevice U-bend specimen for underground exposure,

Figure 4a. Map showing burial order for specimens exposed in 1970 at the various test sites.

First Removal Second Removal Third Removal Fourth Removal Fifth Removal

(1 Yr) (2 Yr) (4 Yr) (8 Yr) (X Yr)

* * * * * * * * * 50x01 50x03 50x05 50x07 50x09 50x11 50x13 50x15 50x17 50x19

51 51 51 51 51 51 51 51 51 51

52 52 52 52 52 52 52 52 52 52 53 5 3 53 53 53 53 53 53 53 53

54 54 54 54 54 54 54 54 54 54

55 55 55 55 55 55 55 55 5.5 1 55 56 56 56 56 JO 56 jo JO 56 56 57 57 57 57 57 57 5 7 5 7 57 57

58 58 58 58 58 58 58 58 58 58

59 59 59 59 59 59 59 59 59 59 60 60 60 60 60 60 60 60 60 60

61 61 61 61 61 61 61 61 61 61

62 62 62 62 62 62 62 62 62 62

63 63 63 63 63 63 63 63 % ] 63 63

64 64 64 64 64 64 64 64 64 64

65 65 65 65 65 65 O J 65 65 65 66x01 66x03 66x05 66x07 66x09 66x11 66x13 66x15 66x17 66x19

50x02 50x04 50x06 50x08 50x10 50x12 50x14 50x16 50x18 50x20

51 51 51 51 Jl 51 e 1 jl Jl 51 51

52 52 52 52 52 52 52 52 52 52

53 53 53 c i jj c; i jj 5 3 J J

e; 1 J J 53 53

54 54 54 jA 54 j4 J4 54 54

55 55 55 55 55 55 55 55 55 55

56 56 56 56 56 56 56 56 56 56

57 57 f; 7 J 1 CTJ I J / 5 7 57 5 7 5 7 57

c; ft JO C Q JO JO K Q JO e; Q JO 58 58 C Q DO 58 58

jy enJ5 c,Q jy COjy c;q jy enjy enJ7 c; n jy 59 59

60 OU OU oU OU oU bU oU 60 60

01 bl 01 01 Ol bl bl 61 61

62 62 62 62 62 62 62 62 62 62 63 63 63 63 63 63 63 63 63 63

64 64 64 64 64 64 64 64 64 64

65 65 65 65 65 65 65 65 65 65 66x02 66x04 66x06 66x08 66x10 66x12 66x14 66x16 66x18 66x20

67x02

68

69

7071

72

7374

75

76

7778

798081

8283

84

85

86

8788

89909192x02

67x04

68

69

70

71

7273

7475

76

7778

7980

8182

8384

8586

8788

89909192x04

67x06

68

69

7071

7273

7475

76

7778

7980

81

82

83

84

8586

8788

89909192x06

67x08

68

69

70

71

7273

7475

76

7778

7980

81

8283

8485

86

87

90

9192x08

67x14 67x16 68x18 68x20

68 68 69 69 69 69 71 71 70 70 73 73

71 71 74 74

72 72 75 75 73 73 76 76 74 74 78 78

75 75 79 79 76 76 81x18 81x20

77 n r67xl8 -67x20

78 78 70x18 70x20

79 79

i \ 80 80

81 81 9192x14

91

92x16 n t x!8 xl8J

72x18

77 -80x18 91x18

I!

tl 92x18

72x20 77x20- 1—80x20

j 91x20

tl 92x20

4"x4" Post

Wire terminal to Dost for electrical measurements

Wire terminals (galvanic couple) to post for electrical measurements. Specimen identification: Digits preceding "x" denote system number (see Table 2) "x" represents site designation. Would be A, B, C, D, E or G depending upon where specimen was exposed. Digits following "x" are specimen numbers.
Figure 4b. Map showing burial order for specimens exposed in 1971 at the various sues.

First Removal Second Removal Third Removal Fourth Removal Fifth Removal

(l yr) (2 yr) (4 yr) (8 yr) (X yr)

ty L_J Li) m l"\ L_i LJ K | 1x01* 1x03* 1x05* 1x07* 1x09* lxll* 1x13* 1x15* 1x17* 1x19*

2x 2x 2x 2x 2x 2x 2x 2x 2x 2x

3x 3x 3x 3x 3x 3x 3x 3x 3x 3x

4x 4x 4x 4x 4x 4x 4x 4x 4x 4x

5x 5x 5x 5x 5x 5x 5x 5x 5x 5x

6x 6x 6x 6x 6x 6x 6x 6x 6x 6x

8x 8x 8x 8x 8x 8x 8x 8x 8x 8x

9x 9x 9x 9x 9x 9x 9x 9x 9x 9x

lOx lOx lOx lOx lOx lOx lOx lOx lOx lOx

14x 14x 14x 14x 14x 14x 14x 14x 14x 14x

15x 15x 15x 15x 15x 15x 15x 15x 15x 15x

16x 16x 16x 16x 16x 16x 16x 16x 16x 16x

17x 17x 17x 17x 17x 17x 17x 17x 17x 17x

18x 18x 18x 18x 18x 18x 18x 18x 18x 18x

19x01 19x03 19x05 19x07 19x09 19x11 19x13 19x15 19x17 19x19

1 x02 T ..A/1

1 x04 1x06 1x08 1x10 1x12 1x14 1x16 1x18 1x20

2x 2x 2x 2x 2x 2x 2x 2x 2x 2x

3x 3x 3x 3x 3x 3x 3x 3x 3x 3x

4x 4x 4x 4x 4x 4x 4x A4x a4x A4x

5x 5x 5x 5x 5x 5x 5x 5x 5x 5x

6x DX 6x 6x 6x 6x 6x 6x 6x 6x

8x 8x 8x 8x 8x 8x 8x 8x 8x 8x

9x 9x 9x 9x 9x 9x 9x 9x 9x 9x

lOx lOx lOx lOx lOx lOx lOx lOx lOx lOx

14x 14x 14x 14x 14x 14x 14x 14x 14x 14x

15x 15x 15x 15x 15x 15x 15x 15x 15x 15x

16x 16x 16x 16x 16x 16x 16x 16x 16x 16x

17x 17x 17x 17x 17x 17x 17x 17x 17x 17x

18x 18x 18x 18x 18x 18x 18x 18x 18x 18x

19x02 19x04 19x06 19x08 19x10 19x12 19x14 19x16 19x18 19x20

20x02 20x04 20x06 20x08

21 x 21x 21x 21x

22x 22x 22x 22x

23x 23x 23x 23x

24x 24x 24x 24x

25x 25x 25x 25x

26x 26x 26x 26x

27x 27x 27x 27x

28x 28x 28x 28x

30x 30x 30x 30x

33x 33x 33x 33x

34 x 34x 24x 34x

35x 35x 35x 35x

36x 36x 36 x 36x

37x 37x 37x 37x

38x 38x 38x 38x

42x 42x 42x 42x

20x10 20x12 20x14 20x16 20x18 20x20

22x 22x 21x 21x 22x 22x

24x 24x 22x 22x 24 x 24x

25x 25x 23x 23x 25x 25x

27x 27x 24x 24x 27x 27x r

21x -21 x 25x 25x r 21x r 21x

23x10 23x12 26x 26x 23x18 23x20

i \

27x 27x

28x

30x

28x

30x -af T 42x 42x 1 26x10 26x12 43x 43x 26x18 26x20

28x — 28x — 44x 44 x 28x — 28x —

1

r

30x -30x 45x14 45x16 r 30x r 30x

33x10 33x12 42x18 42x20

it

n ^B—ii

w

-B u "-B

34x10

II 34x12

35x — 35x —

r-36x r

36x

37x 37x

tl tl L-*-m~*- -B^

It It 38x10 38x12

42x — 42x —

4"x4" post

»- B Wire terminal to post for electrical measurements

B Wire terminals (galvanic couple) to post for electrical measurements.

Specimen identification: Digits preceding "x" denote system number (see Table 2) "x" repr;sents site designation. Would be A, B, C, D, E or G depending upon where

specimer was exposed. Digits following "x" are specimen numbers.
Figure 4c. Map Showing Burial Order for Specimens

Exposed in 1972 at the Various Sites.

First Removal Second Removal Third Removal Fourth Removal Fifth Removal

(1 Yr) (2 Yr) (4 Yr) (8 Yr) (X Yr)

a m H H

7x01* 7x03* 7x05* 7x07* 7x09* 7x11* 7x13* 7x15* 7x17* 7x1 9*

11 11 11 11 11 11 11 11 11 11

12 12 12 12 12 12 12 12 12 12

7x02 7x04 7x06 7x08 7x10 7x12 7x14 7x16 7x18 7x20

11 11 11 , 11 11 11 11 11 11 11

12 12 12 12 12 12 12 12 12 12

m m 1!

- 4"x4" post

^Specimen identification:

Digits preceding "x" denote

system number (See Table 2)

"x" represents site designation. Would be A, B, C, D,

E, or G depending upon where

specimen was exposed.

Digits following "x" are

specimen numbers.


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80 -

60 -

40 -

20 -

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WEIGHT LOSS

PIT DEPTH

293 1

SYSTEM 5255 5 8 535659 54 57 5255 58 53 5859 5457 525559 535659 5457

EXPOSURE

TIME, DAYS'- 377 727 1463

(a)

E

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1/3 s

1000

800

600

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WEIGHT LOSS

PIT DEPTH

. HHH n_ H HHH _H HTI H 1h"1h HH HriSYSTEM '• m%525558 535659 5457 m525558 535659 5457 M525558 535659 5457

65

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TIME, DAYS'- 377 T28

(b)

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E

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1,000

800

600

400

2 00

WEIGHT LOSS

PIT DEPTH

H JUL

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H H H 111

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H45

25

5 SYSTEM: 5255 58 53 5659 5457 52 55 58 53 56 59 54 57 5 2 55 58 535659 54 57

356 719 1355

(c)

EXPOSURE

TIME, DAYS'-

Fig. 7. Average weight loss (mg/dm ) and maximum pit depth (mils) for AISI 300 series

stainless steels after exposure in various soils. See Table 2 for descriptions

of the systems. O-none, N-<1 mg/dm^, H-perforated and T-tunneling.

(a) Site C; (b) Site E; (c) Site G
100

231 U X

S

60 -

40 -

20 -

WEIGHT LOSS

PIT DEPTH

SYSTEMEXPOSURE TIME .DAYS'

are. 5

60646566 6263 60646566 6263

413 771

(a)

J2I

E

CPe

100

80

60

40

20

0

WEIGHT LOSS

PIT DEPTH

U HI

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H jHlHlHH nH _

SYSTEM: 60646566 uiUJiil 6263

EXPOSURE

TIME, DAYS: 3T7

65

45

•25

60646566 62 63

727

(b)

6064 6566 62 63

1463

E

cnE

1000

800 -

600 -

WEIGHT LOSS

PIT DEPTH 1274 1132 1116 X 11

2 4 34 1574 2166 X 11

E

o>E

«f3

SYSTEM: 60646666 6263 60646566 6263 60646566 62 63

1463 EXPOSURE

TIME, DAYS: 377 727

(c)

SYSTEM:

EXPOSURE

TIME, DAYS:

62 63

377 727

(d)

1463

~

E

10,000

5 8,00 0

2 6,0 0 0

I 4,0 0 0 -

LUs

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WEIGHT LOSS

PIT DEPTH 10,199 X

15,243 X

~Jmh U| iiih ii

H H -

1 1 B 1

1

liT B [ BL I"

SYSTEM: 60646566 6263 60646566 6263 60646566 6263

0

EXPOSURE

TIME, DAYS: 356

65

45

25

719

(e)

1355

Fig. 8. Average weight loss (mg/dnr) and maximum pit depth (mils) for AISI 400

series stainless steels after exposure in various soils. See Table 2

for description of the systems. 0-none, N-<5 mg/dm2, I-incipient pitting, S-<5 mils and H-perforated.

(a) Site A; (b) Site C; (c) Site D; (d) Site E; (e) Site G
E

CO* CO

60

40 -

81 WEIGHT LOSS i PIT DEPTH

H

H H

N

SYSTEM: 12 6 3 1718 7 II 12, 12 6 3 17 18 7 II 12 12 6 3 1718

EXPOSURE

TIME, DAYS" 350 350 380 730 730 736

(a)

1086 1086

CME

%

E

WEIGHT LOSS

PIT DEPTH

SYSTEM: 12 6 3 17 18 7 II 12

EXPOSURE

TIME, DAYS'- 350 350 380 728 728 736

(b)

E

a>E

CO

SYSTEM

in

2 6 3 17 18 7 II 12 I 2 6 3 17 18 7 II 12 I 2 6 3 17 18

EXPOSURE

TIME, DAYS: 362 362 362 755 755 736

(c)

1098 1098

Average weight loss (mg/dm ) and maximum pit depth (mils) for Fe-Cr proprietary

stainless steels after exposure in various soils. See Table 2 for description

of the systems. O-none, N-<5 mg/dm2

, I-incipient pitting, S-<5 mils and

H-perforated.

(a) Site C; (b) Site E; (c) Site G
£

£

CO

CO

60 -

40 -

20

WEIGHT LOSS

PIT DEPTH

SYSTEM'-

EXPOSURE

TIME, DAYS:

co 0^ 0 0

-65 °*

-45 1X

25 S

5

4 8 10 5 9 19 4 8 10 5 9 19

730

(a)

1026

E

CP£

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SYSTEM:

EXPOSURE

TIME, days:

CSIE

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CO* CO

SYSTEM:

EXPOSURE

TIME, DAYS'-

WEIGHT LOSS

j? PIT DEPTH

0±.-. OA 0

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5 4 810 5 9 19 4 8 10 5 9 19

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10. Average weight loss (mg/drrr) and maximum pit depth (mils) for Fe-Cr-Ni

proprietary stainless steels after exposure in various soils. See

Table 2 for description of the systems. 0-none, N-<5 mg/dm2

, I-incipient pitting, S-<5 mils and H-perforated.

(a) Site C; (b) Site E; (c) Site G
Fig. 11 Sensitized Type 304 stainless steel

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Table 2. Stainless steel systems in underground corrosion tests

^v*; rem

Burial Year

Stainless

Steel

Spec. . Config. & Size* 3 ' Treatment^)

Passi vation( c ' Procedure Stressed( dipec.

Coupled To

1

1 1 Q71 ?fi Pr-l Mo Sheet (8"xl2") j _ _

0c

ii 1ft i o Cr\j i (Ti) V

' * /

ll

3

it H II II XBW T _ _ „ _

4

ii 20 Cr-24 Ni-6.5 Mo II ll J 5

H II ' * 11 II S J 6 18• \j Cr-2 \s i ' l_ Moi ivy

ll II J 7 1972 18 Cr-2 Mo (Nb) II ll J ._

8 1971 lfi O-fi Ni (N) II ll r __ _ _

g

ii ll II II XBW j ._ 10 H 26 Cr-6.5 Ni

II II J _ _ - -

11 1972 18 Cr-2 Mo (Nb)

ll II XBW J 12 11 ii Tube (2" 0Dxl2") HW J _ _ 14 1971 Composite A Sheet (8"xl2") _ _ 15 II Composite B

II II _ _ 16 II Composite C

II II _ _ _ _ — — 17 II 26 Cr-1 Mo Tube (2" 00x12") HW J 18 II 18 Cr (Ti

)

(1 1/8" 0Dxl2") HW J

.... MS * ; »

19 tl 20 Cr-24 Ni-6.5 Mo (7/8" 0Dxl2")

Sheet (rxl2"J

HW

T __ 20 II 26 Cr-1 Mo J (UU)

21

II II II II T u 22 II 20 Cr-24 Ni-6.5 Mo

n II __ J (UU) 23 II II II II J u 24 ll II II II S J UU _. 25 ll 18Cr-2Mo I II T (UU)

26 II II ll II T u 27 II 1 ft Pr-fl Ni f Ni II II J (UU)

28 II ii II M T u 30 II 26 Cr-6.5 Ni

ll II J u 33 II 26 Cr-1 Mo II ll 11u Zn 34 ll 1 ll II J u Mg

35 II H II II T u Fe 36 II 26 Cr-6.5 Ni

II II _ _ T u Zn 37 II II II II J u Mq

38 II II H II T u Fe 42 jiif.. II II ll T Cu

50 1970 201 Sheet (8"xl2") __ J 51

II 202 II II J 52 II 301 II II T

53 II II ll II s 1(f)

54 II II u II XBW

55 tl 304 ll II

56 II H II ll sHW

T If) 1 V i / 57 II M Tube (2" 00x12")

58 II 316 Sheet (8"xl2")

59 II ii II II s

T 60 II 409 M II III

61 M M II II c 62 II H Tube (1-1/8" 0Dxl2") HW III 63 II H Tube (7/8 " 00x12") HFW III 111 64 II 410 Sheet (8"xl2") III 65 II 430 II II II 66 II 434 II II 67 II 301 Sheet (1 "xl2") HH u 68 II II ll II HH T (uul

69 II II ll It nnhh+<; Tj 1 \T 1 llll UU

70 II II ll II FH u

71 II II II II FH 1 f Hi 1

1

72 II 304 ll II T u 73 H II li II I (Hill \ UU / 74 II II il II nn 1

1

u 75 II II ii II HH J (UU)

76 II II il II s 1(f) llll UU

77 ll 316 II II

1

1

u 78 II ii ll tl J (UU)

79 II ti li II s Iff ) Mil UU 80 II 434 li II

1

1

u —

81 II II ll II

\ uu; 82 II 301 ll II HH 1

1

u 7n 83 II II li II HH I u Mg

re 84 II II ll II HHllll 1

1

U 85 II 11 H II r n 1

1

U LX\ 86

87

II

II

II

II

li

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FH

U

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1

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90

II

II

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li

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llu

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r e

91 II H II 1 I Cu

92 II 409 II II III — Cu

(a) All sheet and tube specimens 0 .064" thick.

(b)All specimens in the annealed condition unless noted otherwise.
Table 2 (Con't.)

Key: S - Sensitized (by heating at 1200°F for 2 hours, followed by air cooling and descaling in sodium hydroxide);

XBW - Cross bead weld (specified to be done in accordance with Welding Research Council recommendations. On half

of these specimens, the welds were cleaned prior to exposure. The other half of the specimens were to be exposed "as welded".

HW - Heliarc weld.

HFW - High frequency weld;

C - Coated;

HH - Half hard;

FH - Full hard.

Passivation procedure:

I. 20 to 40% by volume of 67% nitric acid at 120-160°F for 20-30 minutes.

II. 20% by volume of 67% nitric acid puis 2-6% sodium dichromate at 110-140°F for 20-30 minutes.

III. 20 to 40% by volume of 67% nitric acid at 110-140°F for 20-30 minutes.

Unstressed.

Single U-bend specimen;

Double U-bend specimen, not spot weld;

Double U-bend specimen joined by spot weld.

Welded with a full finish per ASTM Specification A249.

Minimum specified concentration of acid, temperature and time for sensitized materials.

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Table 5. Summary of results^ ' obtained from visual examination of stainless steel

sheet specimens buried in the soils at the NBS soil corrosion test sites.

Specimens of System Nos. 1 through 6, 8, 10, 14, 15, and 16 were buried

for approximately 3 years. System No. 7 was buried for approximately

2 years while others were buried for approximately 4 years.

S,ste„ StainUss Special* Test Results of Vlsua! c-ln.tlo, of Specimens (d)

(c) Exposed 1 year Exposed 2 years Exposed 4 years

Exposed in 1970

50 Type 201 Sheet, A N N anneal ed D

D MIN DC

rL T D LI T,r ,H n/C c\ T TD r\r ,1) ,T,IK

nu

TP1 r YD ,IYTP

t u D T n ,Y , 1 U T P T D r+- t c 1 -S \ rU

fl D T P r*- f cl -i ^ M ,r , 1 r ,t t ^ S 1 i J U I r \ D fl f caw \ TP H(t) ,r,A^sev; ,1Y

51 Type 202 Sheet, A N IP

G II I ltd 1 LU R N

r T D f{ H P(F Fl T TP

D IP DS

E H.T(E) .P. IP H.P.T.IP.IF

G P,IP P,IP

CO Tuna JitccL , M N IP annealed B IP RS

C T,P,IP H,P(F,E),IP

D IP IP

E H H,P,T,IP

G P,T(E),IP T,P,A+Et(sev),IP

53 Type 301 Sheet, A IP.Et Et(E),P,IP

sensitized B IP(E) P(sli),IP

C P.Et Et(sev),P(F,E),IP

D IP(E) P.Bl ,IP

t A(E),P(E,AE),IP,Et Et(sev),Bl ,A(E),P,IP

b Et(mod-sev),P,IP H,A+Et(sev),P,IP

55 Type 304 Sheet, A N IP annual driller a oH 1 cCJ pD N RS

H,T,IP T,P,IP

nLf IF N

L. H P I

P

H,T,P,IP

G H(E),P,IP,Et(sev) A(sev),P,IP

56 Type 304 Sheet, A Et[E(sli)],IP P(sli) ,IP

cpnc 1+1 7pr| p Et(sli),IP N L H,T(E),P H,P(E,AE),T,A(E),IP

IF T,P(E,AE),IP,B1

t H.P.IP H,T,P,IP

G H(E),P,IP H,A,P,IP,Et(sev)

58 Type 316 Sheet, A N IP anneal ed B N N

rL Et.IP IP

nu N N

t A+T(E),P(E,F) H,T,P,IP

G IP IP

59 Type 316 Sheet, A IP(E) P(sli),IP

sensitized B N DS

C P(E,F),H(E) A+P(E),T,Et(sli)

D IP N

E P(E) P,A(E),Et(sli)

G P(E) P,IP,Et(sli)

60 Type 409 Sheet, A IP N annealed B N P(sli)

C P,H(E),Et(sev) H,P,Ft(sev),T,IP

D IF.RS P,T

E H,T(E,F),P H,T(AE,F),P,IP,Et(s1i

G H,Et(sev),P,IP H,P,A(sev),Et,IP

NRS

H,P,T

N

H ,T(E,F),P

P+T(E,AE)

DS

DS+RS(sli)

H,P,T,RS

DS

H,P,T,RS

H,P,RS,DS,IP

NDS(sli)

H,P,T(E,AE)

RS+DS(sli)

H.P+T

H,P,RS,IP

P(sli),IP,RS,DS,Bl

RS.DS

H,P,A(sev-mod)

Bl ,P,IP,Et,A(E)

P(AE,F),B1 ,Cr,RS,IF

P+DS.IP

DS

NH,P+T(E,AE),Et

DS

H.T+P"

P,Et,DS,RS

Et(sli),IP

Et(mod)

H,P,A(sev),IP

Et,P(AE),T(E,AE),Bl

H,T,P,Et,RS

A(sev),P+Et(sli),IP,Et

RS(sli)

DS(sli)

P(E),RS

NH,P(E,AE)

N

P(sli),IP,RS,Et

Et.RS

P,A(E),Et

Et,P,DS

A(E),T(E,F),RS,IF

IP.P.RS

H,P(E,AE,F)^DS

DS.RS

H,P(E,AE,F),A,RS,IP

H,P(E,AE,F),T,Et

)H,T(E,AE,F),RS,IF

H,P(E,AE,F),A(sev)
System Stainless Specimen Type Test Results of Visual Examination of Specimens (d)

steel and Treatment Site

(c) LA|JUicu i ycfli F y nn<; pH ? vpa ExDosed 4 vears

61 Type 409 Sheet, A N N N painted B N N N C N N N U N N N

E N N RS(c)

G N N N

61 Type 409 Sheet, A RS(s) N RS(s)

painted B RS(s) RS(s) N and C RS(s,c) RS[s(sli)],U RS(s)

scored u c,RS(s) RS[s(sli)] Bl+U(s)

E c.RS(s) P+RS(s) ,U,B1 RS(s)

G RS(s) P+RS(s) »U,B1 RS(s)

64 Type 410 Sheet, A P+IP(E,F) T,P,A(E) H,P(E,AE,F) ,DS,IP

annealed B IP N P.IP.RS

C H.P.IP H,P,Et(sev) ,A,IP H ,P(E,AE,F) ,Et+A(sl i

)

u H,P,T,IP H,T,P,A(E),Et(sev), IP H,T(E,AE,F),P(E,F),A(E)

E H(E)T H,T,P,IP H,T(E,AE,F) ,P,RS,DS

G Et(sev) .H.P.IP H,A+Et(sev) ,P,IP H,P E,AE,F ,A(sev)

65 Type 430 Sheet, A Etfsl i KIP IP P,T,IP

annealed B N N IF

C H(E) H,P,T,Et H,P(E,AE,F) ,Et(sl i ) ,A(sev)

u IF T(F) H,T(E,AE,F) ,P

E H,T,IP H,T,P,IP H,P+T(E,AE,F) ,IP,RS

G H,Et(sev) ,P,IP H,P,A+Et(sev) ,IP H,P(E,AE,F) ,A(sev) ,IP

66 Type 434 Sheet, A N IP N annealed B IP N N C H(E) H.P.T.IP H,P(E,AE,F),T(E,AE),Et,IP

D N P(F),IP(E) H,T(AE),P(AE,F)

E H.P.IP H,T,P,IP H,P,T(E,AE,F),RS

G H(E) ,P,IP H,r ,A+tt(Sevj ,1H D/r AC\ [T + / r "I i \ DC r{t ,At ;

, tt { S N ; ,Kb

Exposed in 1971

1 26 Cr-1 Mo Sheet, A IP N DS

annealed B N RS DS

C IP(E) IP,RS P,RS,IP,IF

nu IP Et (si i

)

RS

E IP N IF,RS

G Et(sli),IP N N

2 18 Cr(Ti) Sheet, A P(sli),IP N Et (si i ) ,P,RS

annealed B N Et(sli),RS DS

C H,P,Et,IP Et,P(E,F) ,IP,RS H,P(E,F),Et(sli),IP

nu P(AE) .T.IP N RS

E H,P,T H.P(E.AE.F) .T H.P(E.AE.F) .IP G H,P,A+Et(sev) ,IP H,P(E,AE,F) ,Et,IP P,A(sev) ,IP,RS

4 20 Cr-24 Ni- Sheet, A IP N DS

6.5 Mo annealed B N Et(sli),RS N C IP(E) N N

u N Ft f si i KRS RS

E N N N G N N RS

5 20 Cr-24 Ni- Sheet, A IP N DS

6.5 Mo sensitized B N N DS

C IP Et(sli),IP,RS Et(sli),P(E),RS

u IP Et(sl i

)

IF,DS

E A(E) Ft (si

i

) DS

G P(E) ,Et(sl i ) .IP Et(sl i

)

Ft ( si i ) ,DS

6 18 Cr-2 Mo Sheet, A IP N DS

annealed B IP N DS,IF

1 C T,P(E,F),IP RS P(AE),RS,0S

/ D N Et(sli) RS.IF

E H,P,IP H,P(E,AE,F),RS H,P(E,AE,F)

\ G H,T,A,P,IP H,P(E,AE,F),Et P(E),RS,DS

\
Table 5 (Con't.)

System Stainless Specimen Type Test Results of Visual Examination of Specimens (d)

steel and Treatment Site

(c) Exposed 1 year Exposed 2 years Exposed 4 years

QO 1ft Cr-R Ni ( N) Shppt >J 1 ICC L s A IP N N

r\U nnPri 1 1 1 I CU 11 pH B N RS DS , IF

C IP P,IP,RS P(E),RS,IF

D N Et(sli) ns

£ P(E) P(E) H.P(E.AE) ,RS,IF

G p f F Fl IP H.P,T(E ,AE) ,Et,IP A (mod) .Et(sl i ) .IP

10 26 Cr-6 5 Ni Sheet, A P(sli),IP 1 \ -» • J 9 PTsl i CAE )1 DS

anneal ed B N RS DS

C H,T,P,IP H,T(E),P,IP H,P(E,AF,F),Et(sli)

D N IP N

E H,P,IP H,P,T(E,AE,F) ,IP H,P(E,A£,F) ,IP

G H,P,A+Et(sev) ,IP H,P,T(E,AE) ,IP P,IP,DS,RS

14 Composite A Sheet, hot A Et(sev) ,P P,Et[(sev)AE,F] P(E,AE,F) ,Et

rolled and B Et(sev) ,P,IP P,Et[(sev),AE,F"l,A(E) P(E,AF,F) ,Et

pickled C Et(sev),P P,Et(AE,F),A(E) P(E,AE,F),Et

D Et(sev) ,P P,Et(AE,F) RS,P(E,AE,F) ,Et

E Et[E+F sev)] P,Et(AE,F) RS,P(E,AE,F) ,Et

G Et(sev),Bl ,P(AE) P.Et AE.F ,A(E) P(E,AE,F),Et

15 Composite B Sheet, hot- A N M,c N dip zinc coated B N N N (4.5 oz/sq. ft.- C N N N In) D N

E A[F(sli)] N A[F(sli)]

G P(F),F1(E,AE) P[F(sl i ) J A[F(sli)]

16 Composite C Sheet, hot A Et(sev) ,P(AE,F) P,Et(AE,F) P(E.AE.F) .Et rolled and B Et(sev) ,P P.Et(AF.F) ,A(E) P(E ,AE.F) ,Et

pickled c Et( sev ) .P P.Et(AE.F) P(F AF F) Ft RS

D Et(sev) ,P P,Et(AE,F) RS,P(E.AE.F)Et

E Et(sev) ,P P,Et(AE,F) RS,P(E,AE,F)Et

G Et(sev),P P,Et(AE,F) P(E,AE,F),Et

Exposed in 1972

7 18 Cr-2 Mo(Nb) Sheet, A N P,DS

annealed B N DS

C N P(E,AE),RS,IF

D N N

E P,IP P(AE,F),RS

G N P(E,F)

(a) Results given for each system at each of the six soil test sites are a summary tabulation

for four individual specimens.

(b) Specimen dimensions and treatment for each system are given in Table 2.

(c) Properties of the soils for each of the test sites are given in Table l,

(d) Abbreviations used:

A- Metal attack

AE- Adjacent to edge

Bl- Blisters

BS- Black stain

c- Coating chipped

cr- Specimen cracked

DS- Dark stain

E- Edge

Et- Etched

F- Face

Fl- Coating flaked

H- Perforation

IF- Iridescent film

IP- Incipient pitting

mod- Moderate

N- No apparent attack

P- Pitting

RS- Rust stain

s- Scored area

sev- Severe

si i - Slight

T- Tunnel ing

U- Undercutting
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4-»

-O

OJ

QJ J=

•P

E=

XJ

QJS-S>3U

O

O

O

(0

+-> 4->

(TJ

QJ

CD>

QJ

l/)

QJ

V-O

E

4->

(TJ JZ+J

|>c

Dl

VI>»

<I

(TJ

</) </1 at0 (0

a> +J c 0) +j0 +-> c c

at 0 t- XJ raa. < cu .G

s. +-> 0

c

.'jj

Table 7. Average Weight Loss (mg/dm ) and Pit Depth (mils) for

Stainless Steel Sheet and Tube Specimens Buried in

Sagemoor Sandy Loam (Site A) for up to Four Years

System* Material Treatment

(a)

Average

(b)

Exposure, Weight Loss

Time,

Days mg mg/dm'

Pit Depth, mils (d)

Maximum Average of 5 Deepest

(e)

Exposed in 1970

5n Tvnp ?fil 41 3

791 4 <1

1442 — —

51 Tune 202 413

791 -- IP

1442 --

oc ijrpc oui 41 1

791 — — <5

1442 --

5?9J co 41 7 CODo cD

T D

1 r 791 201 15 <5

1442 1247 98 <5

54 XRW 41 "3 0

c <*> ii 791 2 <1 <5

1442 — —

55 Type 304 413

791 2 <1

1442

56 Type 304 S 413 285 21

791 256 21 <5

1442 618 49

57 TjFpe 304 HW 413 1 <1

791

1442 18

58 Type 316 413 3 <1

791

1442

59 Type 316 S 413 20 2 IP

791 86 6 <5

1442 384 12 7
Table 7 (Con't.)

Average^

System* Material Treat- Exposure, Weight Loss Pit Depth, mils

^

merit Time,

2

(a) Days mg mg/dm Maximum Average of 5 Deepes

(e)

60 Type 409 413 6 <1 29 — — 791 6 <1 <5

1442 150 12 H H

62 Type 409 i ii i HW 413 186 73

791 101 40 IP

1442 32 12 H --

63 Type 409 HFw 413 187 95 IP

791 149 88 <5

1442 75 37 H H

64 Tlm . flirt Type 410 413 3510 281 48 - - 791 82 6 20 7

1442 8843 705 H H

65 Type 430 413 4 <1

791 10 1 IP

1442 66 6 22

66 Type 434 413 4 <1

791 2 <1 IP

1442

Exposed in 1971

1 26 Cr-1 Mo 496 2 <1 IP

860

1147

2 18 Cr(Ti) 496 10 1 IP

860 2 <1

1147 1 <1 <5

3 18 Cr(Ti) XBW 496 1 <1 <5

860 4 <1 <5

1147 4 <1

4 20 Cr-24 Ni- - 496 4 <1 IP

6.5 Mo 860 1 <1

1147 1 <1

5 20 Cr-24 Ni- S 496 1 <1 IP

6.5 Mo 860

1147

6 18 Cr-2 Mo 496 3 <1 IP

860 1 <1

1147
Table 7 (Con't.)

Average

(b)

System* Material Treatment

(a)

Exposure, Weight Loss

Time,

DDays

Pit Depth, mils (d)

mg mg/dm' Maximum Average of 5 Deepest

(e)

8 18 Cr-8 Ni(N) — 496 _ _ _ — IP

860 --

1 147

9 18 Cr-8 Ni(N) XBW 496 20 2 IP

860 -- 1147 2 <1

10 26 Cr-6.5 Ni 496 7 <1 <5

860 <5

1 147 3 <1

14

( r

)

Composite A* ' -- 496 81500 6412 N/A

860 116350 9154 N/A

1 147 1 65175 1 2995 N/A

15 Composite B

lc; HDZ 496 9075 714 N/A

860 21975 1729 N/A

1147 27875 2193 N/A

16

/ \

Composite ' — 496 83775 6591 N/A

860 112175 8825 N/A

1147 149075 11728 N/A

17 26 Cr-1 Mo HW 496 11 3 <5

860

1147 16

18 18 Cr(Ti) HW 496

860

1147 4 2 —

19 20 Cr-24 Ni- HW 496

6.5 Mo 860 — — --

1 147

Exposed in 1972

7 18 Cr-2 Mo(Nb) 364

651 4 <1 <5

11

i 18 Cr-2 Mo XBW 364

(Nb) 651 13 1 — —

12 18 Cr-2 Mo HW 364

(Nb) 651 8 2 <5
Table 7 (Con't.)

*Systems 12, 17, 18,

material , welded at

internal corrosion.

19, 57, 62, and 63 were tube specimens fabricated from sheet

the seams and then plugged and capped at each end to minimize

Specimens of all other systems were flat sheet material.

(a) All materials

Abbreviations

were in

used:

S-sensitized

XBW-cross-bead weld

HW-heliarc weld

the annealed condition unless noted otherwise.

HFW-high frequency weld

HDZ-hot-dip zinc coated (galvanized,

4.5 oz/ft 2

) after bonding. See

footnote (c).

(b) Average for four specimens

(c) All composites were metal lurgically bonded.

Composite A-Carbon steel/Type 430/Carbon steel.

Composite B-Carbon steel/Type 430/Carbon steel.

Composite C-Carbon steel/Type 304/Carbon steel.

(d) 1 mil = 0.025 mm. IP - incipient pitting. H - perforated. N/A - not applicabl

(e) Average of five deepest pits on each of four individual specimens unless noted

otherwise.

(f) Average of ten deepest pits on each of four individual specimens.
Table 8. Average Weight Loss (mg/dm ) and Pit Depth (mils) for

Stainless Steel Sheet and Tube Specimens Buried in

Hagerstown Loam (Site B) for up to Four Years

Material Treatment

(a)

Exposure,

Time,

Days

Average^

Weight Loss

mg mg/dm

Pit Depth, mils

Maximum

(d)

Average of 5 Deepest

(e)

Exposed in 1970

50 Type 201 371

/ JO

1513

c0 < I —

51 Type 202 371

/JO

1513

1 < I —

52 Type 301 371

736

1513

53 Type 301 S 371

736

1513

23

43

206

2

3

15

IP

54 Type 301 XBW 371

736

1513 -- — --

55 Type 304 371

736

1513

56 Type 304 S 371

736

1513

814

690

707

64

55

55

57 Type 304 HW 371

736

1513

58 Type 316 371

736

1513

3 <1

59 Type 316 S 371

736

1513

36

361

3

21
Table 8 (Con't.)

Average

(b)

System* Material Treatment

(a)

Exposure,

Time,

Days

Weight Loss

mg mg/dm

Pit Depth, mils'

Maximum Average o1

(e)

60 Type 409 371

736

1513

4 <1

62 Type 409 HW 371

736

1513

1

1

<1

<1 IP

63 Type 409 HFW 371

736

1513

12

<1

1 IP

64 Type 410 -- 371

736

1513

1474

1207

72

116

98

6

—

65 Type 430 -- 371

736

1513

13

13

1

1

--

66 Type 434 — 371

736

1513

4

6

<1

<1

--

Exposed in 1971

1 26 Cr-1 Mo 394

777

1170

2

1

<1

<1

--

2 18 Cr(Ti) 394

777

1170

12 1 —

3 18 Cr(Ti) XBW 394

777

1170

—

2

—

<1

4 20 Cr-24 Ni

6.5 Mo

- 394

777

1170

7 <1

— —

—

5 20 Cr-24 Ni

6.5 Mo

S 394

777

1170

6 18 Cr-2 Mo 394

777

1170

6

6

<1

<1

(d)
Table 8 (Con't.)

System* Material Treatment

(a)

Average

Exposure, Weight Loss

.2

Time,

Days mg mg/dm

Pit Depth, mils

Maximum

(d)

Average of 5 Deepest

(e)

8 18 Cr-8 Ni(N) -- 394

777

1170 —

--

9 18 Cr-8 Ni (N) XBW 394

777

1170 — --

10 26 Cr-6.5 Ni -- 394

777

1170

--

14 Composite A^ -- 394

777

1170

66575

87425

100400

5238

6878

7899

N/A

N/A

N/A

15 Composite HDZ 394

777

1170

10175

5875

4275

800

462

336

N/A

N/A

N/A

16 Composite C^ -- 394

777

1170

78333

107350

110900

6163

8445

8725

N/A

N/A

N/A

17 26 Cr-1 Mo HW 394

777

1170

4 1 '-_

18 18 Cr(Ti) HW 394

777

1170

2

2

1

1

— — — —

19 20 Cr-24 Ni6.5 Mo

HW 394

777

1170

--

Exposed in 1972

7 18 Cr-2 Mo(Nb) 395

801 1 <1

11 18 Cr-2 Mo(Nb) XBW 395

801 8 <1

12 18 Cr-2 Mo(Nb) HW 395

801 3 <1
Table 8 (Con't.)

*Systems 12, 17, 18, 19, 57, 62, and 63 were tube specimens fabricated from sheet

material, welded at the seams and then plugged and capped at each end to minimize

internal corrosion. Specimens of all other systems were flat sheet material.

(a) All materials were in the annealed condition unless noted otherwise.

Abbreviations used:

S-sensitized HFW-high frequency weld

XBW-cross-bead weld HDZ-hot-dip zinc coated (galvanized,

HW-heliarc weld 4.5 oz/ft2

) after bonding. See

footnote (c).

(b) Average of four specimens.

(c) All composites were metallurgical ly bonded.

Composite A-Carbon steel/Type 430/Carbon steel.

Composite B-Carbon steel/Type 430/Carbon steel.

Composite C-Carbon steel/Type 304/Carbon steel.

(d) 1 mil = 0.025 mm. IP - incipient pitting. N/A - not applicable.

(e) Average of five deepest pits on each of four individual specimens unless noted

otherwise.

(f) Average of ten deepest pits on each of four individual specimens.
It

Table 9. Average Weight Loss (mg/dm ) and Pit Depth (mils)

for Stainless Steel Sheet and Tube Specimens

Buried in Clay (Site C) for up to Four Years

System* Material Treatment

(a)

Average

(b)

Exposure, Weight Loss

Time,

Days

Pit Depth, mils (d)

mg mg/dm' Maximum Average of 5 Deepest

(e)

Exposed in 1970

50 Type 201 —

377 797 64 H - - 727 § Cm § 902 73 H

1463 1242 98 H un

51 Type 202 —

377 509 40 H

727 f Cm t 686 55 Hn

Un 1463 i too 435 34 un Un

52 Type 301 - - 377 193 15 20

727 / Cm t *JCZf 43*t j un

un

i too OH u

n

u

n

53 Type 301 S 377 3672 293 48 15

797 1 CI 1l cyu ?Q51\ 1 UO 1 1 Q 1 H

i too 1 *t 1 OO nop 1 1 CO un

54 Type 301 XBW 377 384 30 63 v mm 797 1 CI oyo OU 1 D

CO

I too coo OCC A"3 ho H un

55 Type 304 377 326 24 H

727 635 49 H

1463 4013 320 H H

56 Type 304 S 377 768 61 H

727 1774 140 H

1463 8022 637 H H

57 Type 304 HW 377

727 89 21 16 5

1463 223 55 7 6

58 Type 316 377 2 <1

727 6 <1

1463 6 <1 63

59 Type 316 S 377 596 49 H

727 735 58 T

1463 988 79 120(T)
Table 9 (Con't.)

Average

(b)

C ti«» ^ Amir IlA 4" a

-i *** D oys tern* via ten a i Treat- exposure

,

Weight Loss Pit Depth, mils ia;

ment Time,

2

(a) Days mg mg/dm Maximum Average of 5

(e)

60 Type 409 377 Duo H

727 / Lm 1 5468 436 H

1463 10349 824 H H

62 Type 409 HW 377 P.09 "3 "30 H

727 2852 1138 H H(f)

1463 3950 1574 H H

63 Type 409 HFW 377 1 ore C/l/l 044

111 ¥ mm f 2176 1116 H H

1463 4226 2166 H H

64 Type 410 377 / UOO ceo DO0

727 15991 1274 H

1463 30574 2434 H H

65 Type 430 377 oon 3/9 H

727 f tm 1 5102 406 H H

1463 Q070 71

H H

66 Type 434 -- 377 541 43 H _ _ 727 955 76 H H(f)

1463 I D 14 1 29 H H

Exposed in 1971

1 26 Cr-1 Mo 350 1 o 1 T DIP

730 IP

1086 — — <5 mm m.

2 18 Cr(Ti) 350 1 U 1 o ol 1

H

730 652 52 42

1086 227 18 H „ ^

3 18 Cr(Ti) XBW 350 coo 46 H

730 163 13 24

1086 101 8 H W, mm

4 20 Cr-24 Ni- 350 1 U < 1 t nIP

6.5 Mo 730 « mm 1086 -- — mm mm

5 20 Cr-24 Ni- S 350 33 3 IP

6.5 Mo 730 IP

1086 14 1 22

6 18 Cr-2 Mo 350 32 2 <5

730 6 <1

1086 1 <1 7
Table 9 (Con't.)

Average

(b)

mils (d) System* Material Treat- Exposure, Weight Loss Pit Depth,

ment Time,

(a) Davs mg mg/dm Maximum Average of 5

(e)

8 18 Cr-8 NifN) -- 350 2 <1 IP —

730 -- <5

1086 5 <1 50 -

9 18 Cr-8 NifN) XBW 350 529 42 141

730 552 44 10 —

1086 554 44 H

—

10 26 Cr-6.5 Ni 350 441 35 H

730 330 26 H H

1086 132 10 H H

14 ComDOsite A^ -- 350 39200 3084 N/A

730 60975 4797 N/A

1086 133000 10463 N/A

15 ComDOsite B^HDZ 350 56825 4470 N/A

730 57950 4559 N/A

1086 80600 6341 N/A

16 Composite C^ -- 350 41000 3226 N/A

730 59175 4655 N/A

1086 126100 9920 N/A

17 26 Cr-1 Mo HW 350 — -- —

730 — -- <5 —

1086 58 14 35 7

18 18 Cr(Ti) HW 350 121 48 H

730 44 18 H H

1086 81 32 H H

19 20 Cr-24 Ni- HW 350

6.5 Mo 730 1 <1 -- 1086 — — — — —

— —

Exposed in 1972

7 18 Cr-2 Mo 380 — <5

(Nb) 736 6 <1 <5

11 18 Cr-2 Mo XBW 380 60 5 <5

(Nb) 736 136 11 H(T)

1 2 18 Cr-2 Mo HW

Aon 380

(Nb) 736 160 39 7
Table 9 (Con't.)

*Systems 12, 17, 18, 19, 57, 62, and 63 were tube specimens fabricated from sheet

material, welded at the seams and then plugged and capped at each end to minimize

internal corrosion. Specimens of all other systems were flat sheet material.

(a) All materials were in the annealed condition unless noted otherwise.

Abbreviations used:

S-sensitized HFW-high frequency weld

XBW-cross-bead weld HDZ-hot-dip zinc coated (galvanized,

HW-heliarc weld 4.5 oz/ft 2

) after bonding. See

footnote (c).

(b) Average for four specimens.

(c) All composites were metallurgically bonded.

Composite A-Carbon steel/Type 430/Carbon steel.

Composite B/Carbon steel/Type 430/Carbon steel.

Composite C-Carbon steel/Type 304/Carbon steel.

(d) 1 mil = 0.025 mm. IP - incipient pitting. H - perforated. T - tunneling.

N/A - not applicable.

(e) Average of five deepest pits on each of four individual specimens unless noted

otherwise.

(f) Average of ten deepest pits on each of four individual specimens.
'J Table 10. Average Weight Loss (mg/dm ) and Pit Depth (mils)

for Stainless Steel Sheet and Tube Specimens Buried in

Lakewood Sand (Site D) for up to Four Years

Average (b)

System* Material Treat- Exposure, Weight Loss Pit Depth, mils^

ment Time,

2

(a) Days mg mg/dm Maximum Average of 5 Deepest

isi

Exposed in 1970

50 Type 201 — 377 3 <1 IP

727 9 <1 40

1463 — —

—

51 Type 202 — 377 -- -- —

727 ^» mm 1463 9 <1 --

52 Type 301 — 377 -- — IP

. 727 1 <1 IP w mm 1463

53 Type 301 S 377 272 21 —

727 1121 88 —

1463 1499 119 30 7

54 Type 301 XBW 377 2 <1 — —

_

727 2 <1 IP -- 1463 — — <5 mm mm

55 Type 304 - - 377 21 2 IP

727 7 <1

1463 -- --

56 Type 304 S 377 297 24 mmx o- 727 740 59 H

mm 1463 1243 99 57

57 Type 304 HW 377

727

1463 8

58 Type 316 377 1 <1

727

1463 — — mm mm

59 Type 316 S 377 127 10

727 172 14

1463 179 14 <5
Table 10 (Con't.)

Average

(b)

System* Material Treatment

(a)

Exposure, Weight Loss

Time,

Days

Pit Depth, mils (d)

mg mg/dm Maximum Average of 5 Deepest

(e)

60 Type 409 377 3 <1 -- -- 727 * 264 21 54

1463 620 49 H H1

1

62 Type 409 HW 377 1 <1

727 5 2 21

1463 83 34 MI I H

63 Type 409 HFW 377 10 6 H

727 44 21 H

1463 10 6 H 1 .

64 Type 410 377 160 12 H 727 1159 92 H

1463 920 73 H H

65 Type 430 377 2 <1

727 29 2 18

1463 186 15 H H

66 Type 434 377 3 <1

727 8 <1 56 —

1463 56 3 H H

Exposed in 1971

1 26 Cr-1 Mo -- 350 2 <1 IP -- 727 — —

1086

2 18 Cr-(Ti) -- 350 17 1 23 -- 727 — — —

- - 1086

3 18 Cr (Ti) XBW 350 8 <1 26 14

727 — — — — - - 1086

4 20 Cr-24 Ni- 350 6 <1 -- 6.5 Mo 727 - — — — —

1 086

5 20 Cr-24 Ni- S 350 6 <1 IP -- 6.5 Mo 727 -- -- 1086

6 18 Cr-2 Mo -- 350 4 <1

727 1 <1

1086 1 <1

8 18 Cr-8 Ni (N) — 350 4 <1 IP

727

1086
Table 10 (Conf .)

Average

(b)

System* Material Treatment

(a)

Exposure, Weight Loss

Time,

Days

Pit Depth, mils (d)

mg mg/dm' Maximum Average of 5 Deepest

(e)

9 18 Cr-8 Ni (N) XBW 350 30 2

_ _ — _ 727 IP

1086

10 26 Cr-6.5 Ni -- 350 6 <1 _ _ 727 — . 1086

14 Composite A^

c ' -- 350 27000 2124 N/A

111 32075 2523 N/A

1 086 act r\f\ 451 00 3b4o M / A N/A

15 Composite B

l } HDZ 350 5375 423 N/A

111 Lost N/A

1086 1 200 94 M / A N/A

16 Compsite C

[c) 350 26750 2104 N/A

727 38900 3060 N/A

1086 48000 O "7 "7 C 3776 N/A

17 26 Cr-1 Mo HW 350 6 2 M Ml _ _ 111 -- 1086

18 18 Cr (Ti) HW 350

111

1086 3 1 --

19 20 Cr-24 Ni- HW 350

6.5 Mo 111 -- --

1 086

Exposed in 1972

7 18 Cr-2 Mo (Nb) 380

736 2 <1

11 18 Cr-2 Mo XBW 380 4 <1

(Nb) 736 36 3

12 18 Cr-2 Mo (Nb) HW 380

736 6 2
(

Table 10 (Con't.)

*Systems 12, 17, 18, 19, 57, 62, and 63 were tube specimens fabricated from sheet

material, welded at the seams and then plugged and capped at each end to minimize

internal corrosion. Specimens of all other systems were flat sheet material.

(a) All materials were in the annealed condition unless noted otherwise.

Abbreviations used:

S-sensitized HFW-high frequency weld

XBW-cross-bead weld HDZ-hot-dip zinc coated (galvanized,

HW-heliarc weld 4.5 oz/ft2

) after bonding. See

footnote (c).

(b) Average for four specimens.

(c) All composites were metallurgical ly bonded.

Composite A-Carbon steel /Type 430/Carbon steel.

Composite B-Carbon steel/Type 430/Carbon steel.

Composite C-Carbon steel/Type 304/Carbon steel.

I (d) 1 mil = 0.025 mm. IP - incipient pitting. H - perforated. N/A - not applicable!

(e) Average of five deepest pits on each of four individual specimens unless noted

otherwise.

(f) Average of ten deepest pits on each of four individual specimens.
Table 11. Average Weight Loss (mg/dm ) and Pit Depth (mils)

for Stainless Steel Sheet and Tube Specimens Buried in

Coastal Sand (Site E) for up to Four Years

System* Material Treatment

(a)

Exposed in 1970

50 Type 201

Exposure,

Time,

Days

377

727

1463

Average (b)

Weight Loss

2

1302

3324

5705

104

262

454

Pit Depth, mils (d)

mg mg/dm Maximum

H

H

H

Average of 5 Deepest

is}

l(f)

51 Type 202 377 778 62 H

727 1948 155 H

1463 1939 155 H

52 Type 301 377 1339 107 H

727 2737 217 H

1463 2320 183 H

53 Type 301 S 377 1396 110 <5

727 3744 299 8

1463 4873 387 28

54 Type 301 XBW 377 1768 85 H

727 2558 204 H

1463 2828 225 H

55 Type 304 377 1425 113 H

727 3162 250 H

1463 4564 363 H H

56 Type 304 S 377 2820 232 H

727 5912 470 H H

1463 11088 881 H H

57 Type 304 HW 377 641 156 38

727 1432 348 26

1463 1352 329 53 21

58 Type 316 377 174 14 H

727 534 46 H

1463 83 6 H

59 Type 316 S 377 1350 107 62

727 3302 262 <5

1463 3306 262 H

60 Type 409 377 3309 262 H

727 3952 314 H

St'f)

1463 5235 418 H H
Table 11 (Con't.)

Average

^

Exposure, Weight Loss

merit

(a)

i ime,

Days mg i 2

mg/dm 1Maximum

HW 377 752 299 H

727 1270 506 H

1463 2417 964 H

HFW 377 763 390 H

727 1033 531 H

1463 1521 TOT

781 H

377 4005 317 H

727 4012 320 H

1463 8477 674 H

-- 377 1448 115 H

111 3174 253 H

1463 5084 405 H

377 1603 1 28 H

TOT 727 3113 247 H

1463 5174 412 H

350 6 <1 IP

728 —

1087 1 <1

350 555 44 H

728 464 37 H

1087

ATA

250 20 H

XBW 350 544 43 H

728 688 55 H

1087 350 28 H

350 2 <1

728 1 <1 —

1087 1 <1

S 350 121 10

728 65 5

1087 65 5

350 615 49 H

728 534 42 H

1087 224 18 H

Pit Depth, mils

'erage o (1)

(d)

62 Type 409

63 Type 409

64 Type 410

65 Type 430

66 Type 434

Exposed in 1971

1 26 Cr-1 Mo

2 18 Cr (Ti)

3 18 Cr (Ti)

4 20 Cr-24 Ni

6.5 Mo

5 20 Cr-24 Ni

6.5 Mo

6 18 Cr-2 Mo

H

H

H

H

H

H

H, % H(n

H

H(f)

H

K(f)

H

H(f)

H

H

H

H

H

H
Table 11 (Con't.)

Average

(b)

System* Material Treatment

(a)

Exposure, Weight Loss

Time,

Days mg mg/dm'

Pit Depth, mils

^

Maximum Average of 5 Deepest

8 18 Cr-8 Ni (N) -- 350 25 2 — — 728 12 1 24 -- 1087 56 4 H

9 18 Cr-8 Ni (N) XBW 350 922 73 H _ _ 728 1536 122 H

1087 1776 142 H

10 26 Cr-6.5 Ni 350 403 32 H

_ _ 728 1082 86 H H

1 087

1 AAA

1093 87 H H

14 Composite A^

c; -- 350 24200 1904 N/A

728 27125 2134 N/A

i not

1 087 39100 30/D M / A N/A

/ \ 15 Composite fT

c; HD2 350 12175 958 N/A

728 1350 106 N/A

1087 12575 989 HI 1 A N/A

16 Composite C^ — 350 20275 1595 N/A

728 17750 1396 N/A

1087 38450 3025 N/A

17 26 Cr-1 Mo m 350 6 2 13

728 4 1 5

1087 2660 650 50 16

18 18 Cr (Ti ) HW 350 6 2

728 — *- 1087 3 1 -- --

19 20 Cr-24 Ni- HW 350 1 <1

6.5 Mo 728 — --

-% Ann

1087 1 <1

Exposed in 1972

7 18 Cr-2 Mo (Nb) — 380 <5

736 4 <1 <5

11 18 Cr-2 Mo XBW 380 515 41 H

(Nb) 736 516 41 H

12 18 Cr-2 Mo HW 380 162 40 H H

(Nb) 736 356 87 H
Table 11 (Con't.)

Systems 12, 17, 18, 19, 57, 62, and 63 were tube specimens fabricated from sheet

material, welded at the seams and then plugged and capped at .each end to minimize

Internal corrosion. Specimens of all other systems were flat sheet material.

(a) All materials were in the annealed condition unless noted otherwise.

Abbreviations used:

S-sensitized HFW-high frequency weld

XBW-cross-bead weld HDZ-hot-dip zinc coated (galvanized,

HW-heliarc weld 4.5 oz/ft2

) after bonding. See

footnote (c).

(b) Average for four specimens.

(c) All composites were metal! urgically bonded.

Composite A-Carbon steel/Type 430/Carbon steel.

Composite B-Carbon steel/Type 430/Carbon steel.

Composite C-Carbon steel/Type 304/Carbon steel.

(d) 1 mil = 0.025 mm. IP - incipient pitting. H - perforated. N/A - not applicable

(e) Average of five deepest pits on each of four individual specimens unless noted

otherwise.

(f) Average of ten deepest pits on each of four individual specimens.
Table 12. Average Weight Loss (mg/dm ) and Pit Depth (mils)

for Stainless Steel Sheet and Tube Specimens Buried in

Tidal Marsh (Site G) for up to Four Years

System* Material Treatment

(a)

Average (b)

Exposure, Weight Loss

Time,

Days mg mg/dm'

Pit Depth, mils (d)

Maximum Average of 5 Deepest

[e]

Exposed in 1970

50 Type 201 356 3754 299 45

719 1199 95 H

1355 78 6 35

51 Type 202 356 60 5 40

719 18 1 33 7

1355 85 7 H H

52 Type 301 356 165 12 40

719 1117 88 30

1355 218 18 H H

53 Type 301 S 356 5016 400 25

719 13123 1046 H

1355 2185 108 36 13

54 Type 301 XBW 356 49 4 13

718 1603 128 62 9

1355 1400 112 12

55 Type 304 356 930 73 H

719 1829 146 36 11

1355 304 24 37 6

56 Type 304 S 356 322 24 20

719 6191 494 H

1355 5146 409 26 8

57 Type 304 HW 856 1 <I

719 4 <1 10 3

1355 2 <1 11 5

58 Type 316 356 7 <1 <5

719 3 <1 <5

1355

59 Type 316 S 356 11 <1 <5

719 92 6 <5

1355 <5

60 Type 409 356 31407 2501 H H

(f)

719 66328 5283 H HV)

1355 23206 1848 H H

(f)
Table 12 (Con't.)

Average

(b)

System* Material Treatment

(a)

Exposure, Weight Loss

Time,

Days

Pit Depth, mils (d)

mg mg/dm< Maximum Average of 5 Deepest

(e)

62 Type 409 HW 356 8448 3367 H 1 / r- \ 719 17055 6795 H H

(f)

1 Job AOT Q 1 COT

1 DO 1 H H

63 Type 409 HFW 356 4691 2403 H

719 19912 10199 H

1 ODD 1 UUOt D 1 J3 u

n un

64 Type 410 _ _ 356 31997 2547 H H

719 70709 5630 H H(mf ) 1355 104434 8314 H H

cc Tuna A"ir\ oo iype 4JU ODD AA9QA u

n H

(f)

71 Q 1 UODfC R9RG u

n n v ' 1355 191351 15243 H H

66 Type 434 ODD QQyy

oOu

n

71 Q / 1 y

7*397 u

n 1355 6 —

Exposed in 1971

1 26 Cr-1 Mo _ _ 362 5 <1 IP —

755 3 <1 — —

i uyo

2 18 Cr (Ti) 362 11974 954 H —

755 33777 2691 H H

i uyo Dyo*f HI 1 0/

3 18 Cr (Ti) XBW 362 3712 296 H

—

755 815 65 28

I uyo J < I <D

4 20 Cr-24 Ni- 362 1 <1 _ _ 6.5 Mo 755 -- -- --

1 098

5 20 Cr-24 Ni- S 302 1 52 12 t nIP

6.5 Mo 755

1098

6 18 Cr-2 Mo 362 402 32 H

755 630 50 H H

1098 <5

8 18 Cr-8 Ni (N) 362 56 4 5

755 159 13 H H

1098 2 <1
Table 12 (Con't.)

Average

(b)

System* Material Treatment

(a)

Exposure, Weight Loss

Time,

Days

Pit Depth, mils (d)

mg mg/dm' Maximum Average of 5 Deepest

isl

9 18 Cr-8 Ni (N) XBW 362 905 72 110 —

755 3409 272 11

1098 2 <1

10 26 Cr-6.5 Ni 362 4770 380 H __ 755 248 20 H H

1098 14 1 7 6

14 Composite A^

c ' 362 113275 8912 N/A

"7 r F" 755 380200 2991

1

M / A N/A

1098 398800 31374 N/A

15 Composite B^

CJ HDZ 362 57825 4549 N/A

755 66250 5212 ft 1 / A N/A

1098 49300 3878 N/A

16 Composite C^ 362 105400 8292 N/A

755 256400 20172 N/A

1098 358000 28165 N/A

17 26 Cr-1 Mo HW 362 2 <1

755 57 14 <5

1098 4 1 <5 --

18 18 Cr (Ti) HW 362 3468 1383 H

755 24641 9825 H H

1098 15115 6027 H H

19 20 Cr-24 Ni- HW 362 -- -- — -- 6.5 Mo 755

1098

Exposed in 1972

7 18 Cr-2 Mo (Nb) — 362

736 11 <1 45

11 18 Cr-2 Mo (Nb) XBW 362

736 7 <1 45

12 18 Cr-2 Mo (Nb) HW 362

736 9 2 IP
Table 12 (Con't.)

Systems 12, 17, 18, 19, 57, 62, and 63 were tube specimens fabricated from sheet

material, welded at the seams and then plugged and capped at each end to minimize

internal corrosion. Specimens of all other systems were flat sheet material.

(a) All materials were in the annealed condition unless noted otherwise.

Abbreviations used:

S-sensitized HFW-high frequency weld

XBW-cross-bead weld HDZ-hot-dip zinc coated (galvanized,

HW-heliarc weld 4.5 oz/ft2

) after bonding. See

footnote (c).

(b) Average for four specimens.

(c) All composites were metal lurgically bonded.

Composite A-Carbon steel/Type 430/Carbon steel.

Composite B-Carbon steel/Type 430/Carbon steel.

Composite C-Carbon steel/Type 304/Carbon steel.

(d) 1 mil = 0.025 mm. IP - incipient pitting. H - perforated. N/A - not applicabl

(e) Average of five deepest pits on each of four individual specimens unless noted

otherwise.

(f) Average of ten deepest pits on each of four individual specimens.
Table 13. Summary of Results Obtained from Non-Gal vanical ly Coupled

Stressed 1 -in x l2-1n Stainless Steel Specimens After Exposure

for up to 4 Years at the Six NBS Soil Corrosion Test Sites

System Stainless Treatment Stressed Exposure Number of Specimens Failed

steel (a) Specimen Time-

(b) years Site A Site B Site C Site D Site E Site G

Exposed in 1970

67 Type 301 HH U 1 0 0 0 0 0 0

2 0 0 1(c) 0 0 0

4 0 0 0 0 0 0

68 Type 301 HH (UU) 1 0 0 0 0 0 0

2 0 0 0 0 0 0

4 0 0 0 0 0 0

69 Type 301 HH+S uu 1 l(d) l(d) 2(d) 2 2 1 2 1 0 2 2 2 1 A4

o

c

1

1 9c

9

c od

70 Type 301 FH u 1 0 0 0 0 0 0 2 0 0 0 0 0 0

4 o o o n nu n

71 Type 301 FH (UU) 1 0 0 0 0 0

2 0 0 0 0 0 l(d)

4 o n nu n nu nu

72 Type 304 -- u 1 0 0 0 0 0 0

2 0 0 0 0 0 0

AH

nu

n md* U U U 0

73 Type 304 -- (UU) 1 0 0 0 0 0 0

2 0 0 0 0 0 0

AH U n

u U n

U 0 0

74 Type 304 HH u 1 0 0 0 0 0 0

2 0 0 0 0 0 0

4 0 0 0 0 0 u

75 Type 304 HH (UU) 1 0 0 0 0 0 0

2 0 0 0 0 0 0 4 0 0 0 0 0 0

76 Type 304 S UU <: fjn I 0 0 0/'

» 0 1 0

2 0 0 !_T(d) 0 0 0

4 0 0-NR* 0 0 0 0

77 Type 316 u 1 0 0 0 0 0 0

2 0 0 0 0 0 0

4 0 0 0 0 0 0

78 Type 316 (UU) 1 0 0 0 0 0 0

2 0 0 0 0 0 0

4 0 0-NR* 0 0 0 0

79 Type 316 S UU 1 0 0 0 0 0 0

2 0 0 0 0 0 0

4 0 0 0 0 0 0

80 Type 434 U 1 0 0 0 0 0 0

2 0 0 0 0 0 0

4 0 0-NR* 0 0 NR* 0

81 Type 434 (UU) 1 0 0 0 0 0 0

2 0 0 0 0 0 0

4 0 0 0-NR* 0 0 0

ixposed in 1971

20 26 Cr-1 Mo (UU) 1 0 0 0 0 0 0

2 0 0 0 0 0 0

3 0 0 0 0 0 0
Table 13 (Con't.)

System Stainless Treatment Stressed Exposure Number of Specimens Failed

steel \o ) -> (J c L 1 Ulfcr 1

1

(b)

1 tine years Site A Site B Site C Site D Site E Site

21 26 Cr-1 Mo U 1 0 0 0 0 0 0

2 0 0 0 0 0 0

3 0 0 0 0 0 I*

22 20 Cr-24 Ni-6. 5 Mo — (UU) 1 0 0 0 0 0 0

2 0 0 0 0 0 0

3 0 0 0 0 0 0

23 20 Cr-24 Ni-6 5 Mo U 1 0 0 0 0 0 0

2 0 0 0 0 0 0

- 3 0 0 0 0 0 0

24 20 Cr-24 Ni-6 5 Mo — UU 1 0 0 0 «M

0 0 0

2 0 0 0 0 0 0

3 0 0 0 0 0 0

25 18 Cr-2 Mo (UU) 1 0 0 0 0 0 0

2 0 0 0 0 0 0

3 0 0 0 0 0 0

26 18 Cr-2 Mo U 1 0 0 0 0 0 0

2 0 0 0 0 0 0

3 0 0 0 0 0 0

27 18 Cr-8 Ni(N) (UU) 1 0 0 0 0 0 0

2 0 0 0 0 0 0

3 0 0 0 0 0 0

28 18 Cr-8 Ni(N) u 1 0 0 0 0 0 0

2 0 0 0 0 0 0

3 0 0 0 0 0-MR* 0

30 26 Cr 6.5 Ni u 1 0 0 0 0 0 0

2 0 0 0 0 0 0

3 0 0 0 0 0 0

*Specimen

(a) All

not retrieved

specimens in the annealed condition unless noted otherwise

HH-half hard

FH-full hard

S-sensitized

(b) U-single U-bend specimen

UU-double U-bend specimen

(UU)-double U-bend specimen, joined by a spot weld

(c) Micro crack on face, specimen considered failed

(d) Micro crack on edge, specimen considered failed
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NBS-1 >4A (REV. 7-73)

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO.

NBSIR-76 1081

2. Gov't Accession

No.

3. Recipient's Accession No.

4. TITLE AND SUBTITLE

Progress Report on the Corrosion Behavior of Selected Stainless

Steels in Soil Environments

5. Publication Date

August 11, 1976

6. Performing Organization Code

7. AUTHOR(S)

W. F. Gerhold, E. Escalant.P, and R. T. Sanrfprsnn

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No. 3120362

11. Contract/Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

American Iron and Steel Institute

1000 16th Street, N.W.

Washington, D. C. 20036

13. Type of Report & Period

Covered

p rogress Report

1970-1974

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less (actual summary ol most significant information. If document includes a significant

bibliography or literature survey, mention it here.)

In order to obtain more definitive information regarding the corrosion and stress

corrosion of stainless steels in soil environments, NBS in cooperation with the

Committee of Stainless Steel Producers, AISI, initiated in 1970 a soil burial program

in representative soil environments. Test materials included coated and uncoated

sheet specimens in the annealed and sensitized condition, uncoated welded tubing

specimens and g*lvanically coupled and uncoupled stressed and unstressed specimens.

To date approximately 10,000 specimens have been buried at six soil test sites.

This report contains the results obtained for specimens buried for up to approximately

four years.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons)

Coatings; corrosion behavior; field tests; galvanic couples; soil environment;

stainless steels; stress-corrosion behavior.

18. AVAILABILITY [X Unlimited

1 For Official Distribution. Do Not Release to NTIS

1

1 Order From Sup. of Doc, U.S. Government Printing Office

Washington. D.C. 20402. SD Cat. No. C13

1 ! Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

21. NO. OF PAGES

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

22. Price

USCOMM-DC 29042-P74