The Use of the Slow Strain Rate

Technique for the Evaluation of

Structural Materials for

Application in High-Temperature

Gaseous Environments

C. E. Johnson and G. M. Ugiansky

Corrosion and Electrodeposition Group

Chemical Stability and Corrosion Division

Center for Materials Science

U.S. Department of Commerce

National Bureau of Standards

Washington, DC 20234

January 1981

I Final Report

-tiC—

lUO

,U56

81-2191

1981

C.2

'repared for Inited States Department of Energy

Inder Contract No. EA-77-A-01-6010

NBSIR 81-2191 (DoE)

THE USE OF THE SLOW STRAIN RATE

TECHNIQUE FOR THE EVALUATION OF

STRUCTURAL MATERIALS FOR

APPLICATION IN HIGH-TEMPERATURE

GASEOUS ENVIRONMENTS

" Of

UBltAXT

JUL 2 0 1981

UCi ^

C. E. Johnson and G. M. Ugiansky

Corrosion and Electrodeposition Group

Chemical Stability and Corrosion Division

Center for Materials Science

U.S. Department of Commerce

National Bureau of Standards

Washington. DC 20234

January 1981

DISTRIBUTION OF THIS DOCUMENT IS UNLIMITED

Final Report

Prepared for United States Department of Energy

Under Contract No. EA-77-A-01-6010

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director
^ wm

•e«i 0 s juc

i ? ',- ^ ,

)j*0) i9'S-m»nSM

©OAojA'^g .^i f»o^ gui)Mh3Tr

>»0^':*WAmaTAM ARUTaUlSTS

SW'iTr ‘E'sWjW’.-HiaiM VN w^Aotm»> F-a»*w)^a 3uo3»At)

<

. » t''

V

wV,.,

.w

^ ,v

• • -4^

-

k: »e .4i^ .'

roi ''^il

." 1 . , #'

:i ,p

«M”:J

p

T».

‘J*' '"

:.

• •ii'

4>,i

'< 'V'Hi

Vf'-''

I

MfS?;:,

m.4^‘

^ ' !»

*9

,|V ' '

. , '* dm.JlP I^-'''*,:'

»t3

^ -..^^--.^.9-.— , >|« m\ym - »! i i.i|f p—i i m i ji p

i h i i, 'ai :ai'gr A; -i r 'rWf;
FOREWARD

Since 1974, the National Bureau of Standards has been engaged

in research designed to address succinct materials problems and

needs pertinent to coal conversion and utilization technologies.

This work, sponsored in part, at first by the Office of Coal

Research, then ERDA and currently the DOE, focuses on test method

development, particularly accelerated procedures for materials

behavior and durability; on the determination of the mechanisms of

materials degradation; and on the development and operation of

materials data centers to provide evaluated information on

properties and performance including failures occurring in operating

pi ants

.

During the FY 77-79 period the NBS program, entitled

"Materials Research for the Clean Utilization of Coal", consisted of

a number of interrelated tasks including:

1. Metal Corrosion

a. Slow Strain Rate Test

b. Pre-cracked Fracture Test

2. Ceramic Deformation, Fracture and Erosion

3. Chemical Degradation of Ceramics

a. Reactions and Transformations

b. Slag Characterization (viscosity)

c. Vaporization and Chemical Transport

4. Failure Prevention

a. Failure Information Center

b. Materials Properties Data Center

The results of the research have been disseminated through quarterly

reports of progress (available from NTIS; report designation

EA-6010; Dist. Category (UC-90C) as well as numerous scientific

publications in technical journals. Further, as individual tasks

are completed, an overall report is prepared detailing the results

and accomplishments of the project. This present publication is the

final report for the project on Metal Corrosion-Slow Strain Rate

Test Technique.

SAMUEL J. SCHNEIDNER

Program Manager

Center for Materials Science

National Bureau of Standards
ABSTRACT

The slow strain rate technique has been evaluated as an accelerated test for determining the performance of structural

materials in simulated coal gasification environments. Seven

alloys, namely Types 309, 310, 310S, 347 and 446 stainless

steels; Incoloy 800; and Inconel 671, were tested at

temperatures from 370'*C to 1040 C(700*F to 1900®F) at strain

rates from 10 "^ to 10 ~^/s in H 2 S plus water, gaseous

mixtures of CO, CO 2 , H 2 , CH 4 , H 2 S, and H 2 O, and in

nominally inert environments of He and Ar. Type 310 steel, the

most extensively studied material, showed a marked reduction in

mechanical properties at low strain rates {<l0~^/s) in

H 2 S/H 2 O at 5 40 °C ( 1000 °F ) , and this was associated with the

occurrence of a large degree of secondary intergranular cracking

in addition to the main ductile fracture mode. The occurrence

of the secondary cracking was taken as the primary indication of

embrittlement in subsequent tests. Of particular significance,

it occurred to some degree in all alloys tested in the simulated

coal-gasification environments at 600°C ( 1100®F ) . Comparison of

the results for the nonstabi 1 i zed austenitic steels with those

for the stabilized grade. Type 347, indicated that sensitization

had a detrimental effect with respect to intergranular cracking,

although it was not clear that it is a necessary condition for

this type of failure. The secondary cracking was

surface-initiated in all alloys except the Inconel 671, which

failed by the formation of internal cracks associated with the

temperature and strain-induced a-chromium phase. While there

was clearly an effect of environment on the behavior of the

former alloys, interpretation was hindered by the absence of

base-line data for an inert environment, since the nominally

inert media caused limited oxidation. Consequently, the

mechanism(s) of the embrittlement phenomena remain uncertain; a number of possible causes including creep and several

environmentally-induced fracture processes are outlined, it is

shown that the overall results of the test program are in good

agreement with in-plant experience. it is concluded that the

slow strain rate technique is an effective method for evaluating

the performance of structural materials in the

elevated-temperature gaseous environments.
INTRODUCTION

-1 -

This study of the mechanical behavior of structural alloys

in gaseous environments at elevated temperatures was initiated

primarily to support current effo'rts in the development of the

technology to convert the Nation's abundant coal reserves to

gases of both high and low BTU values. The behavior of materials

under such conditions was largely unexplored at the start of this

investigation. The thrust of the program was not to test

specific alloys, but to evaluate an accelerated test method for

materials selection for this demanding application.

Specifically, the slow strain rate technique (SSRT) was

investigated.

Previous work utilizing this technique had been confined

largely to the study of stress-corrosion cracking (SCC) and

hydrogen embrittlement in aqueous media.* The test involves the

application of a slow strain rate to smooth, i.e., un-notched,

tensile specimens which are simultaneously exposed to the

environment being investigated, and yields data of the type shown

in Fig. 1. Region A, where strain rates are too slow to lead to

SCC, the rate of repassivation is thought to be rapid enough to

prevent any damaging interaction between the environment and the

bare metal exposed during straining. At the opposite extreme.

Region C, the strain rate is so rapid that failure occurs by the

normal ductile mode, the time being insufficient for

environmental interaction to have a significant effect. It is

only in the intermediate range of strain rates. Region B, where

the rate of production of bare metal is sufficiently high so that

the rate of repassivation does not effectively stifle

environmental reaction and the strain rate is sufficiently slow

so that ductile fracture does not predominate. Under these

conditions, SCC takes place. If SCC is not possible for the

system studied, the reduction in ductility shown in Region B does

not occur; the presence or absence of this reduction of

mechanical properties is the essence of the SSRT,

The SSRT has become widely used in the study of SCC, both

for mechanistic investigations and as a routine method for

mater i al s/ env i ronment evaluation. The advantages of the method

are the relatively short testing times required, and the severe

nature of the test -- it will promote SCC where other tests will

not, unless inordinately long times are used. While it is

extremely useful for ranking materials, it should be noted that

the detailed interpretation of the results is not clear. The

reduction in area, strain to fracture, and maximum tensile stress

are commonly used as measures of susceptibility, but it is not

established whether the reduction in these parameters relates to

crack initiation, propagation or a combination of these

processes. Moreover, no clear relationship exists between the

results of the SSRT and those of other test methods.

*A monograph has recently been published, describing the SSRT in

considerable detail [1].
- 2 -

The environmental conditions encountered in coal

gasification, i.e., high-temperature gases, are basically

different from those in the aqueous SCC systems which have been

studied by the SSRT. The present studies were carried out to

determine whether the method can be used to evaluate materials

for the gaseous case. The tests were carried out on several

candidate materials for use in proposed coal -gas i fi cation

systems, namely several austenitic stainless steels (Types 309,

310, 310S and 347), a ferritic stainless steel (Type 446), and

two nickel-base alloys (Inconel 671 and Incoloy 800). These

materials were also being included in a DOE-s ponsored study of

h i gh- tempera ture corrosion-erosion [2]. The main test

environments used were the gases He and Ar; H^S plus steam, and

H

2 S saturated with water vapor at 23®C; and mixtures of CO, C02>

H 2 > CH 4 , H 2 S and H 2 O. He and Ar were used to provide baseline

data. The wet H 2 S environments were employed because of the high

probability of embrittlement in those environments, based on the

known susceptibility of austenitic alloys to SCC in sulfide

environments in oil refineries. The gaseous mixtures of CO, C 02 » H 2 > CH 4 , H

2 S, and H 2 O simulated possible coal gasification

environments

EXPERIMENTAL PROCEDURES

Materials and Specimen Preparation

The compositions and heat treatments of the alloys used are

given in Table 1. Note that two different batches of Type 310

steel were used. All the alloys were received in the form of 9.5

mm(0.375 in) diameter rods. The heat treatments were performed

by the suppliers and no further heat treatment was carried out.

The microstructures of the alloys are shown in Fig. 2.

The specimens were 58 cm(23 in) long by 9.5 mm(0.375 in) in

diameter, and threaded on both ends for attachment to universal

couplings outside the test cell. A central gauge section of

effective length 2.5 cm (1.0 in) and diameter 4 mm (0.16 in) was

produced by machining. The gauge section was subsequently

polished using 320, 400, and 600 grit silicon carbide papers,

respecti vel y , followed by a final polish using CROCUS cloth. The

surface was finally rinsed with acetone and alcohol, and air

dried.

Test Facility

The SSRT facility is capable of testing four specimens

simultaneously and is equipped with automatic digital data

acquistion and storage. The facility is illustrated

schematically in Fig. 3. A range of strain rates from 10“3/s to

10"7/s (over the 2.5 cm(1.0 in) gauge length) was achieved

through the use of different gear ratios, reduction gear boxes,

and variable speed motors. The tensile load was measured by a load cell with a maximum capacity of 900 kg(2000 lb) and an

output of 39.6 uV/kg(18 yV/lb). The strain was measured by means

of a LVDT attached across the shoulders of the specimen, at

points outside the furnace. Fig. 3; the LVDT was calibrated to
- 3 .

give an output of 13.33 V/m(0. 34/in). The elongation was

determined after fracture from gauge marks on the reduced

section of the specimen. Reduction in area measurements were

made by measuring the diameter of the reduced section before and

after testing using a stage micrometer. The load cells and

LVDTs were sequentially scanned and their outputs were read on a digital multimeter and stored in a programmable calculator.

These data were transferred to magnetic tape or flexible

magnetic disc memory for later use in constructing stress-strain

curves or other curves of tensile strength, elongation, or

reduction in area versus strain rate.

The test cells were Type 304 stainless steel tubes (38

cm(15 in) long by 5 cm(2.0 in) diameter sealed at both ends with

Type 304 plates using Viton-A gaskets. The cells were mounted

in furnaces capable of producing test temperatures up to 1100

C(200°F). Ports for entrant and exit gases, thermocouples, and

specimens were available on the end plates. Fig. 3. Sliding

seals of Teflon or high vacuum 0-ring couplings provided freedom

of movement for specimen extension while testing. These seals

are limited in use to below 300 C(570°F) and therefore were

located outside of the furnace and cooled with fresh air.

The specimens were positioned in the test cell so that the

reduced section was in the center of the cell and furnace. Fig.

3. The cells were purged with either N, Ar , or He. The test

gas then was introduced into the cells and the furnaces brought

up to test temperature. The specimens were pre-loaded to 100

kg (220 lb) to produce a positive output from the load cell.

Data were taken at predetermined load intervals (approximated by

dividing the expected maximum load by the number of data

registers available), usually 0.3 mV or 0.4 mV [corresponding to

7.5 kg(16.5 lb) or 10 kg(22 lb).

Test Environments

The main environments were He, Ar, H 2

S plus steam, and

H 2

S saturated at 23®C(73®F) with H 2 O vapor (wet H 2 S), and

gaseous mixtures of CO, CO 2 , H 2 , CH 4 , H 2 S, and H 2 O;

limited tests were conducted in air, H 2 , and in vacuum. The

inlet gas compositions and the calculated equilibrium

compositions of the simulated coal gasification environments are

given in Table 2.

RESULTS AND DISCUSSION

Austenitic Stainless Steels

Type 310 : Specimens were initially tested at 540°C(1000®F) in

the H 2 S environments. Typical stress-strain curves are shown

in Fig. 4, and the various fracture parameters are presented in

Fig. 5 and Table 3. It can be seen that the UTS, elongation and

% reduction in area (RA) are markedly reduced at strain rates of

7.2 X 10"^/s and slower. SEM examination indicated that the

reduction in the tensile parameters was associated with the

appearance of large numbers of surface cracks. Fig. 6 . These

formed throughout the gauge section and were approximately

perpendicular to the stress axis, e.g.. Fig. 6 (d). In the case
-4-

of specimens showing reduced tensile properties, the central

region of the primary fracture surface was ductile with a flat

outer rim corresponding to the surface cracks. These cracks,

seen below to be intergranular, are considered to be responsible

for the degradation of the tensile properties at the slower

strain rates. It can be seen in Fig. 6(a) and (b) that failure

at the higher strain rates occurred by ductile shear; it should

be noted that secondary shear cracks formed near the primary

fracture. Figs. 6(a) and (b), are readily distinguished from the

intergranular cracks, cf. Fig. 6(d). A thick scale was formed

on the specimens and quantitative analysis indicated that it

consisted of a duplex oxide-sulfide layer. Appendix A.

For comparison purposes, specimens were also tested in He

at 540®C ( 1 000®F) . The results. Fig. 5, indicated that the RA was

again decreased at the lower strain rates, and SEM examination

revealed the presence of intergranular cracks. A visible oxide

film was observed, raising the possibility that this was

responsible for the reduced RA. The supplier's analysis of the

He gave a value of O 2 content of 0.1 to 0.5% while H^O was listed

at 2-250 ppm. Accordingly, further testing was carried out at a strain rate of 10’6/s in He which was first passed through heated

Ti filings, phosphorus pentoxide, and a liquid-nitrogen trap;

tests were also carried out in Ar and vacuum (2 x 10’2 Torr).

Intergranular cracking occurred in each case. Fig. 7. However, a visible oxide film was detectable in each case, so that the

environments cannot be regarded as inert. A hard vacuum test cell

probably would have prevented the oxide on the specimens, but

equipment and time were not available to test this idea.

Subsequent testing in a reducing environment of H? also

produced a thin interference oxide film on the surface of the

specimens. Cracking was also detected in these specimens in

tests at 540°C ( 1 000®F) at a strain rate of 10’6/s. Figure 8

shows the intergranular cracking on the surfaces of the gauge

section, and the intergranular facets on the primary fracture

surface. The rim of intergranular cracking extended 250-400 ym

from the free surface, and the remaining fracture surface

corresponded to ductile shear.

It is probable that sensitization, detected from a chemical etch test, occurred during testing at 540®F( 1 000®F) , and

that carbide precipitation at grain boundaries and the associated

chromium depletion played a role in the intergranular failures.

To pursue this possibility, tests were run at a strain rate of

10-6/s at 81 5®C(1 500®F) and 1 040®C(1 900®F) . The former was

designed to give information near the top of the sensitization

range, while the latter would give results above the temperature

range for sensitization. These tests were run in air because the

seals of the test chambers were not designed for these high

temperatures. At 81 5®C(1 500®F) , the UTS was only 173 MPa(25 KSI)

versus 414 MPa(60 KSI) when tested in He at 540®C( 1 000®F) at the

same rate; the RA was 14.5% which was a lower value than obtained

for that parameter for any test at 540®C(1 000®F) . Many secondary

intergranular cracks were observed in this specimen. Fig. 9(a)

and (b), and the primary fracture consisted largely of

intergranular facets, in contrast to the shallow rim of
-5-

i n tergranul ar cracking observed at 540 °C ( 1 000 ° F) , The

intergranular nature of the secondary cracks is evident from Fig.

9(c). Intergranular cracking also occurred in the test at

1040°Cp900®F)» thus ruling out the possibility that

sensitization is necessary for this form of failure. The RA was

21%, UTS 76 MPa(ll KSI) in this case, and the elongation 41%.

The latter was probably due to the more uniform yielding over the

entire reduced section at the higher temperature.

To further investigate the role of sensitization,

specimens were tested at a strain rate of 10"6/s in dry He and Hz

at 370“C(700°F) and 450°C(840°F) , both below the nominal

temperature range for sensization. Examination of fractured

specimens suggested that partial sensitization had in fact

occurred. Figs. 10(b) and 11(b). However, the primary fracture

was entirely ductile and no secondary intergranular cracks were

detected. Figs. 10(a) and 11(a). The tensile properties were

higher than in comparable tests at 540 ®C ( 1 000 ° F) , e.g.. Fig. 12.

In a further attempt to separate the effect of sensitization from

that of combi ned thermo-mechanical processes, a test was made by

heat-treating the unstressed specimen at 540°C( 1 000°F) for a time

equivalent to the time required for specimen failure when tested

at a strain rate of 10-6/s (approximately 60h). The Type 310

specimen failed in a ductile manner when subsequently tested at

540°C ( 1 000°F) at a higher strain rate of lO’^/s. These tests

showed the need for simultaneous application of the slow strain

rate (lO’^/s) and the sensitization temperature (>450®C) for the

occurence of Intergranular cracking.

Testing in simulated coal gasification environments. Table

2, was carried out at two test temperatures, one below the

nominal sensitization range (450°C) and one within this range

(600°C). A strain rate of 10“6/s was chosen, based on the

preceding tests. The tensile data are shown in Fig. 13. None of

the specimens failed by intergranular cracking when tested at

450®C(840®F) in any of the three environments ( ul tra-pure hel i urn

,

oxidizing/sulfidizing, or ox idizing/sulfidizing/ carburizing).

Photomicrographs of the fractured specimens, scanning electron

micrographs of the fracture surfaces, and photomicrographs of the

sectioned specimens tested in the three environments are shown in

Figs. 14-16. These photographs show the ductile fracture and the

partially sensitized grain boundaries. The variation in the

measurements of the mechanical properties in each case are within

measurement error. When tested at 600°C(1 1 00®F) , a large amount

of intergranular cracking occurred in the three environments as

revealed in Figs. 17-19. The oxidizing/sulfidizing environment

seemed to produce the largest reductions in mechanical

properties. Fig. 13.

As a precaution against the possibility that the Type 310

material may be from a bad lot, or harbored some pecul ari t i es

,

another lot of Type 310 Steel (RA 310) was tested in ultra-pure

He at 600°C(1 1 00®F) at a strain rate of 10"6/s. jhe composition

of RA 310 is shown in Table 1. The RA 310 failed in the same

manner as the Type 310 SS, that is, with considerable amounts of

intergranular cracking. The UTS, elongation, and RA for both

lots tested in ul tra- pure-He at 600®C(1 1 00®F) are as follows:
- 6 -

Type 310 RA310

UTS 368 MPa(53,400psi

)

337 MPa(48,800psi

)

Elongation 19.9% 19.2%

RA 28.8% 23.6%

Type 310$ : The C content of this alloy was slightly lower than

in Type 310, Table 1, and, if sensitization were important, this

alloy should therefore be less susceptibile to intergranular

cracking. Initial tests were conducted in wet H

2

S at

540 °C ( 1 000°F) . In contrast to Type 310, no intergranular

cracking was observed over the range of strain rates from 10"^ to

10"7/s. There was a reduction in the magnitude of elongation and

RA at the strain rates of 10"6/s and 10"7/s, but these did not

reach the low levels found in the Type 310, Table 4, Fig. 20.

Type 31 OS specimens tested in He and "house" vacuum (726mm

Hg) at 540®C(1 000°F) at a strain rate of lO'^/s exhibited

elongation and RA values twice as great as were seen for Type 310

tested under the same conditions, see Fig, 20. However, numerous

intergranular cracks were present in the Type 310S specimens.

Clearly, the lower C content does not eliminate intergranular

cracks. The reason for the absence of such cracks in the wet H 2

S

is not known, though it may be speculated that the scale formed

in this environment protects the specimens from damaging

environmental interaction. It should also be noted that creep

resistance of materials has been reported to be greater in air

than in He and vacuum [3,4]; this will be discussed further

below.

Further testing was done in the simulated coal gasification

environments. Test tempeatures of 450(840®F) and 600®Cp 1 00®F)

,

and a strain rate of 10-6/s were used for direct comparision with

Type 310. The stress-strain data are shown in Fig. 21. The

higher values of the tensile parameters at 450®C(840®F) are

presumably due to the fact that no significant intergranular

cracking occurred at 450®C(840®F) , Figs. 22-24, whereas this form

of cracking was prevalent at 600®C( 1 1 00®F) , Fi gs . 25-27. It can

be concluded that the lower C content in Type 310S does not

impart significantly greater resistance to intergranular cracking

in coal -gasi f ication environments.

Type 347 : This alloy was tested because it is stabilized with Nb

and Ta, Table 1, to resist sensitization. Specimens were

initially tested in wet H 2 S at 540®C(1 000®F) over a range of

strain rates from 10”4 to 10"7/s. The results are tabulated in

Table 5 and shown graphically in Fig. 28. The elongation was low

compared with those for Type 310 and Type 310S, cf. Tables 3-5,

but the UTS and RA were comparable to the other alloys. More

importantly, the tensile properties of Type 347 specimens were

not strongly sensitive to strain rate. Fig. 28, and this was

consistent with the finding that no intergranular cracking

occurred at any of the strain rates. Further specimens were

tested at 540®C { 1 000°F) in He, and house vacuum (723 mm Hg), No

intergranular cracking was detected over the range of strain

rates of 5 x 10“5 to 8.4 x 10“7/s, and the mechanical properties

were not significantly different from those in wet H 2 S, see Fig.
-7-

28 for He.

Tests were carried out at 450°C(840°F) and 600°C(1100®F) in

ultra-pure He and in the simulated coal gasification atmospheres,

i.e., oxidizing/sul fidizing and oxi di zing/sul fi di zi ng/carburizi ng

,

using a strain rate of 10‘d/s. The resulting stress-strain curves

are shown in Fig. 29. No intergranular cracking was observed at

450®C(840°F) in either environment. Figs. 30-32. The

UTS values were higher at 450°C(840°C) than at 540 °C ( 1 000 ® F)

Elongation was still relatively low (17-19%), while RA was high

(60-66%) due to necking. In some of the first tested specimens,

tool marks were present on the reduced area, but these did not

seem to act as stress-raisers. Subsequent specimens were

polished to remove the tool marks. At 600°C(1100®F), the tensile

properties were lower than at 450°C(840°C) in all of the test

environments. Fig. 29. Small surface cracks were detected in the

necked regions next to the fracture surface in specimens tested

in He, Fig. 33, and in the oxi di zi ng/sul fi di zi ng/carburizi ng

environment. Fig. 34, but no cracks were visible in the case of

the oxi d i zi ng/sul fi di zi ng case. Fig. 35. The cracks were shallow

and were confined to the necked region, and there was no significant difference in mechanical properties for the three

environments. Figs. 29 and 33-35. It is not clear whether the

cracks shown in Figs. 33 and 34 are the same type as the

intergranular cracks in the other alloys. However, it is clear

that the stabilized alloy is far less susceptibile to this form

of cracking. Thus the absence of sensitization may be beneficial

with respect to intergranular cracking.

Type 309 : Limited tests were carried out on this alloy, which is

similar in composition to Type 310 except for its lower Ni and Cr

contents and higher Si content. Table 1. The Type 309 specimens

were tested at 600®C(1 1 00°F) , in various environments and at

several strain rates and the results were compared to those for

Type 310 tested under similar conditions. Stress-strain curves

for both alloys tested at a strain rate of 10"^/s in He are shown

in Fig. 36. The ductility of Type 309 is far greater, see also

Table 6, and this correlates with the small amount of surface

cracking observed in this alloy. Fig. 37, compared to that in

Type 310, Fig. 17. The cracking in Type 309 is shallow and is

confined to the necked region; no well defined rim of

intergranular fracture could be detected at the main fracture, in

contrast to the case of Type 310. Similar shallow secondary

cracking was observed in tests on Type 309 specimens at

600®C ( 1 1 00 ®F) in Ar and the oxi di zi ng/sul fi di zi ng/ carburizing

atmosphere; the tensile parameters for these atmospheres are

given in Table 6.

The microstructure of the Type 309 steel was found to

contain ferrite, in which carbides were precipitated during

testing at 600°C(1 1 00°F) , Fig. 38. There was no evidence for the

formation of sigma phase, which is known to be formed from

ferrite during long times at high temperatures. The presence of

the ferrite may account for the greater resistance of Type 309 to

intergranular cracking in our tests, but its specific role was

not determined.
- 8 -

Ferritic S ta inless Steel

Tests were carried out on Type 446 steel, selected because

of its resistance to corrosion and oxidation at high

temperatures. Tests were carried out at 450°C(840°F) and

600®C ( 1 1 00 °F) in ultra-pure tank He and in the simulated coal

gasification environments, i.e., oxi di zi ng/sul fi di zi ng and

oxi d i z i ng/s ul f i di z1 ng/ car bur i zi ng , using a strain rate of 10"6/s.

The resulting stress-strain curves are shown in Fig. 39. The

data for 450°C(840®F) were not significantly different for the

three environments, despite the fact that shallow surface cracks

were visible within the necked region of specimens tested in the

coal gasification environments. Figs. 41 and 42, but not in the

He test. Fig. 40. The nature of the shallow cracks, i.e., interor transgra nul ar , was not determined. At 600®C(1 1 00®F) , UTS

values were significantly lower than at 450®C(840®F) in all test

environments, and the elongation and RA were higher. Figs. 39 and

43-45. The mechanical properties can be seen to be significantly

lower for the coal gasification environments compared to the

specimen tested in He. Surface cracking was visible in the

necked region in the three environments. Figs. 43-45, but the

morphology was different in the coal gasi fi cation cases , the

cracks adopting a mosaic pattern. Despite the apparent

environmental effect, the overall failure was ductile in each

case, as evidenced by the large values of elongation and RA.

Moreover, the question of whether environmental reactions occur

at this temperature is academic, since it is clear from a comparison of the UTS values at 450®C(840®F) and 600°C(11 00®F)

that the latter is above the temperature at which this alloy

should be used under stress.

Nickel Base Alloys

Incoloy 800 : Specimens were initially tested at 540®C(1 000®F) in

the wet H 2S environment over a range of strain rates from 10’^ to

10"7/s. However, severe scaling occurred in this environment,

drastically reducing the cross-section. Fig. 46, so that the

tensile data had no meaning. It is clear that the alloy cannot

be used in this environment at elevated temperatures.

Further testing was carried out in the simulated coal

gasification environments and in ultra-pure He at 450®C(840°F)

and 600®C(1 1 00®F) at a strain rate of 10"^/s. The stress-strain

curves. Fig. 47, indicate that the properties were markedly

affected by both the oxi di zi ng/sul fi di zi ng and oxidizing/

sulf id i zing/carburizing atmospheres . However, no secondary

cracking was observed at 450®C( 1 1 00®F) in any of the three

environments, and the values of RA were essentially the same.

Figs. 48-50. At 600®C(1 1 00®F) , secondary cracks were found in

the regions of the fracture in each env i ronment , but were more

shallow in the case of He, Figs. 51-53.
-9-

I nconel 617 : This alloy was tested since it has found some use

as a weld overlay in coal gasification pilot plants. Tests were

confined to 450°C(840®F) and 600°C(1100®F) in the simulated coal

gasification environments and ultra-pure He, using a strain rate

of 10"6/s. The stress-strain curves were almost coincident for

all three environments at each temperature. Fig. 54. However,

shallow secondary cracks were visible near the primary fractures

in both coal gasification atmospheres at 450°C(840°F) , but not in

the case of He, Figs. 55-57. The primary fractures were ductile

in character in each case, but involved less necking than in

other alloys tested; this is evident from the relatively low

values of RA, Figs. 55-57. At 600®C( 1 1 00°F) , the strengths and

ductilities were considerably reduced. Fig. 54, and this was

associated with the presenceof a-tchromium in each case. Figs.

58(c), 59(c) and 60(c). Studies of sections of the fractured

specimens indicated that numerous secondary cracks, many of which

were internal, occurred within the a-chromium or at the interface

between this phase and the matrix. The amount of a-chromium was

found to decrease with increasing distance from the primary

fracture. Fig. 61, and thus it seems that the formation of this

phase is assisted by strain. It is concluded that the poor

mechanical properties of the alloy at 600 ®C ( 1 1 00° F) are due to

the presence of the a-chromium phase, which was both temperatureand strain-induced. Because of the internal nature of the

cracking in many instances, it appears unlikely that the presence

of the environments had any influence on the formation or

fracture of this embrittling phase.

COMPARISON OF RESULTS OBTAINED FROM THE SSRT WITH IN-PLANT EXPERIENCE *

The present results for the main envi ronment/ tempera ture

combinations are summarized in Table 7. Embrittlement is

identified by the occurrence of secondary cracking (SC); this was

intergranular in the case of Type 310 specimens but was not

characterized in some of the other materials. The results

indicate that Type 310 steels undergo embrittlement at

540°C(1 000°F) and 600°C in various gaseous media. Several

in-plant failures are consistent with these findings. A Type 310

gasifier probe in the Consol plant was reported to fail by

stress-enhanced intergranular corrosion [5]. Tests showed the

sensitization of the steel when operated between 425 - 875°C (800

- 1600°F), which was thought to significantly reduce the

corrosion resistance of the grain boundaries. A Type 310 N 2

purge line from the Hygas plant failed by brittle fracture due to

grain boundary embrittlement and S corrosion when operated at 760

- 875°C (1400 - 1600°F)[6]. A Type 310 welded tube (inlet line

to regeneration) in the CO 2 Acceptor plant failed [7J

,

^Information on our plant performance was obtained from the NBS Failure

Prevention Information Center. The identification number of each report

is given in the References so that they may be obtained from the Center.
Corrosion due to S was the fundamental cause of failure but was

accentuated by the stress and strains from the fluidized bed and

thermal cycling which was the immediate cause of failure . A

cracking failure was reported in a Type 310 nozzle plate in the

Westinghouse multi-stage coal gasification system [8]. Cracking

was due to high thermal stresses set up during thermal cycling.

The cracking progressed along massive carbide precipitates along

grain broundaries. The synthesis gas environment could have been

oxidizing or reducing at 980 - 1300®C(1800 - 2400®F). Failure of

a Type 310 air distributor plate from an atmospheric fluidized

bed combustor resulted from embrittlement due to sigma phase

formation along with intergranular carbide precipitates [9].

Plant exposure of the plates resulted in a decrease in ductility

at elevated temperatures, especially at 840®C(1 550®F) , Other

plant reports have indicated that no failures have occurred with

Type 310 when used at temperatures of 350 - 470®C(660 - 875®F)

even at pressures up to 17 MPa(2500 psi).

Type 347 steel was seen to perform significantly better

than Type 310 in the SSRT, and again this is consistent with

pilot-plant experience. Thus, no evidence of cracking was found

in the initial examination of Type 347 top closure flanges or

inlet nozzles to the dissolver vessel in the Solvent Refined Coal

plant operated at 525®C(975®F) at a pressure of 21 MPa(3000 psi)

[10]. However, subsequent examination of the Type 347 cover

plate on the SRC dissolver vessel revealed cracks that were very

shallow and exhibited a pattern suggestive of a partially

intergranular failure mode [11]. Thermal cycling during welding

and residual stresses were expected in the cracked regions, and

it was speculated that these effects contributed to this

cracking. Four cracked ares were detected on the top surface of

the Type 347 flange between the gasket grove and inner wall of

the dissolver vessel. All appeared to be relatively shallow.

From the location and appearance of the cracks, it was speculated

that these occurred at regions that were mechanically damaged or

perhaps repair welded.

Some secondary cracking was observed in our tests of the

ferritic steel at both 450®C(840®F) and 600®C( 1 1 00®F) , but it was

clear that the latter is above the normal operating range for

this material. An in-plant failure report also revealed the same

results [12]. Two Type 446 thermowells failed in the Battelle's

Aggl omerati ng-Burner Process Development Unit and it was

recommended that lower temperatures be used.

Incoloy 800 was seen to undergo embrittlement in the

600®C ( 1 1 00®F) tests. There have been numerous in-plant service

failures in this material. Fourteen cracking failures of

schedule 40 Incoloy 800 pipe have occurred in the Westinghouse

gasification PDU at temperatures of 315®C(600®F) [13]. These

failures were closed to welds, but not necessarily in the weld

metal or HAZ. Evidence indicates that the failures resulted from

intergranular SCO. The material was heavily sensitized. The

corroding agent was not identified. An Incoloy 800 nozzle

reducer cracked and failed in the Synthane plant [14]. The

operating environment was aqueous condensate at 205®C(400®F) and

pressure of 4 MPa(600 psi). The crack appeared to have occurred
-1

-

in the HAZ. Failure was due to intergranular SCC of the sensitized

material, and caused a 5-week shutdown of the plant. An Incoloy 800

pipe union developed a 360° circumferential crack in the central pipe

weld on the cyclone (C119) of the Westinghouse system [15].

Environmental conditions were product gas at 925 - 1035 ®C ( 1700-1900 °F

)

at a pressure of 1.5 MPa(200 psi). Cracking was reported to be due to

SCC. Cracking was observed in a schedule 40 Incoloy 800 pipe which

was part of a line in the second stage gasifier reactor in the Hygas

pilot plant [16]. The pipe transported char and gas at 815 ° C ( 75 0 °F )

Fracture occurred immediately adjacent to a welded flange. It was

noted that the cracking mode changed with increasing depth from

intergranular at the surface to transgranu 1 ar at the crack tip. It

was speculated that the change in crack mode might be due to an increase in the effective stress as crack depth increases, chemical

effects at the surface, or chemical changes at the crack tip. The

laboratory tests suggested that Incoloy 800 is an useful material at

400®C. An in-plant service report bears this out. An Incoloy 800

preheater coil in the Hygas plant has operated for 3820 h of coal

processing at a maximum temperature of 400°C(750°F) at a pressure of

17 MPa(2500 psi) [17].

The tests on Inconel 671 indicated that degradation of

mechanical properties resulted from the formation of the a-chromium

phase at 600°C. This is in essential agreement with the

recommmend at i on that in-plant use be restricted to cladding material

and not for structural purposes. The alloy has been found to be a good material for high temperature corrosion resistance, but the

elevated temperature mechanical properties are poor and cannot be

recommended for components subject to directional stresses [18].

GENERAL DISCUSSION AND CONCLUSIONS

The present results clearly demonstrate the usefulness of the

SSRT as a method of evaluating the performance of materials in gaseous

environments at elevated temperatures. This is seen in the strong

correlation between the test data and in-plant experience, discussed

in the preceding section. The results of Type 310 steel tested at

5 40 °C { 1000 ®F ) in the H 2 S/H 2 O environment show a reduction in

mechanical properties as the strain rate decreased from 10“^/s to

10"5/s and below. Table 3 and Fig. 5; it was seen in the

Introduction that such a reduction is indicative of the operation of

an embrittling process. The reduction in properties in the case of

Type 310 specimens was seen to be associated with the occurrence of

secondary intergranular cracking, and this was taken as an indication

of embrittlement in subsequent tests on this and other alloys. It

should be noted that, while the RA exhibited a decrease with

decreasing strain rate, it did not show the increase at lower strain

rates commonly observed in the case of SCC in aqueous media. Fig. 1.

Thus, there does not appear to be an analogous effect to the

repassivation which occurs in aqueous environments.

The mechanism of the intergranular fracture observed in Type 310

steel and in certain of the other alloys was not determined. In

particular, it was not established whether the failure was due to

creep or to some environmentally-induced fracture process. For the

austenitic materials, temperatures of 5 40 ®C ( 1000 °F ) and above are in
- 12 -

the range where creep can occur [19]. To pursue this possibility, it

would be necessary to carry out tests under constant load in inert

environments (see below) as well as under the same

environmental /temperature conditions used in the SSR tests. A number

of environmentally-induced fracture processes could be proposed to

account for the intergranular fractures. For example, it has been

suggested that such failures can be produced by an oxide-rupture

mechanism [20], similar to that advocated for certain aqueous

st res s-corros i on systems [21,22]. Alternatively, it could be

speculated that embrittlement resulted from the penetration of grain

boundaries by oxygen; or, in the S-bearing environment, by the

formation of brittle sulfide compounds [23]. The present results do

not permit us to distinguish between these possibilities, and it is

clear that further work is necessary in this area.

A major uncertainity in the present work concerns the influence

of the environments. This arises because of the absence of baseline

data for inert environments — it was seen that thin oxide layers were

produced by each nominally inert medium such as He and Ar. As

indicated in the text, it would be necessary to construct a test

chamber capable of maintaining a hard vacuum (M0“^ torr) to resolve

this question. Another parameter which was not evaluated is the

influence of initial grain size. It was seen in Fig. 2 that

significant variation existed between the different alloys, but no

attempt was made to investigate the effect of this variation on

mechanical behavior.

Comparison of the results for Type 310 and the stabilized

austenitic steel. Type 347, indicates that sensitization has a detrimental effect on the high-temperature mechanical properties.

Such an effect would be expected if the intergranular failures

resulted from creep, since sensitization is known to adversely affect

the creep resistance of austenitic stainless steels [19]. It could

also be rationalized in terms of a stress-corrosion mechanism, since

the chromium-depleted regions at the grain boundaries in sensitized

material would be expected to be preferentially oxidized.

In summary, the SSRT has been shown to be a useful method for

evaluating the performance of structural materials under conditions

simulating those in coal-gasification plants. The mechanism(s) of the

embrittlement phenomena encountered during the tests was not

determined, and this serves to emphasize the need for further work in

this important area.

ACKNOWLEDGEMENTS

The support of this work under the project "Materials Research

for the Clean Utilization of Coal" for the U.S. Department of Energy

(Contract No. EA-77-A-01-6010 is gratefully acknowledged. We thank J.

Kruger for the many helpful discussions; E. N. Pugh for his assistance

in the preparation of this report; C. H. Brady for the work on the

optical and scanning electron micrographs; and W. A. Willard for the

in-plant service failure reports. We also wish to thank I. G. Wright

of Battelle Columbus Laboratories for information on the gas

equilibrium compositions and phase equilibrium.
- 13 -

PULICATIONS

Ugiansky, G. M. and Johnson, C. E., "Slow Strain-Rate Stress

I Corrosion Testing of Metals in Gaseous Atmospheres at Elevated

Temperatures", Stress Corrosion Cracking-The Slow Strain-Rate

Technique, ASTM, STP 665, G. M. Ugiansky and J. H. Payer, Eds.,

American Society for Testing and Materials, pp. 113-131, (1979).

;l

j Ugiansky, G. M. and Johnson, C. E., "Stress Corrosion Testing at

i Elevated Temperatures in Simulated Coal Conversion Gases",

J Proceedings of 7th International Congress on Metallic Corrosion,

Vol. II, ABRACO, Rio de Janiero, pp. 915-924, (1979).

i

I TALKS

i

I

I "Constant Strain-Rate Stress Corrosion Testing for Coal Gasification

S Systems", Workshop on Materials Technology for Coal Gasification

I (Gaithersburg, Maryland: National Bureau of Standards, September,

I 1975).

"Constant Strain-Rate Stress Corrosion Testing", ASM-AIME Joint

National Meeting, 1975 Materials Science Seminar (Cincinnati, Ohio:

November, 1975). (Invited).

"Constant Strain Rate Stress Corrosion Testing for Coal Gasification

Systems", NACE Annual Meeting (Houston, Texas: March, 1976).

"Constant Strain Rate Stress Corrosion Testing of Metals at Elevated

Temperatures", Mechanical Failures Prevention Group Symposium on

Prevention of Failures in Coal Gasification Systems (Columbus,

Ohio: Apr i 1 , 1976 )

"Constant Strain Rate Stress Corrosion Testing at Elevated

Temperatures", General Electric Co., Research and Development Center

Staff Seminar (Schenectady, NY: February: 1977). (Invited).

"Constant Strain Rate Stress Corrosion Testing of Metals in Gaseous

Environments at Elevated Temperatures", ASTM/NACE Symposium on Stress Corrosion Cracking - The Constant Strain Rate Technique

(Toronto, Ontario: May 1977).

"Slow Strain Rate Stress Corrosion Testing in Coal Gasifier

Environments", First International Conference on Materials for Coal

Conversion and Utilization (NBS, Gaithersburg, Maryland: October,

1977 )
-14r

"Stress Corrosion Testing at Elevated Temperatures in Simulated Coal

Conversion Gases", 7th International Congress on Metallic Corrosion,

(Rio de Janeiro, Brazil; October, 1978).
- 15 -

REFERENCES

[1]

Stress Corrosion Cracking - The Slow Strain Rate Technique,

[2] Ugiansky, G. M., and Payer, J. H., editors, ASTM STP 665, 1979

Hill, V., Corrosion-Erosion Study of Materials for the

Gasification of Coal, IITRI Reports to Metal Properties

Council under DOE Contract Number EX-76-C-01-1784

.

[3]

Shepard, 0. C., and Schalliol, W., Symposium on Corrosion of

Materials at Elevated Temperatures, ASTM STP 108, April 1951.

[4] Hosoi, Y., and Abe, S., Met. Trans. A., 1975, p. 1171.

[5] Leterle, J. F., Continental Oil Co. Technical Service Report,

No. 116-74-1301, May 13, 1974; National Bureau of Standards - Failure Prevention Information Center Identification Number 98

[6]

Danyluk, S., Argonne National Laboratory Service Failure

Report, Dec. 22, 1976; NBS-Failure Prevention Information

Center Identification Number 255.

[7]

Schulz, C. A., Conoco Materials and Component Failure Report,

No. 75-8, Aug. 8, 1975; NBS-Failure Prevention Information

Center Identification Number 144.

[8]

Albertin, L., et al., Westinghouse Technical Document Summary,

No. 75-8D9-PDU0P-P1, Nov. 25, 1975; NBS-Failure Prevention

Information Center Identification Number 191.

[9]

King, R. T., et al.. Oak Ridge National Laboratory Report

ORNL/TM-6444, Feb. 1979; NBS-Failure Prevention Information

Center Identification Number 609.

[10]

King, R. T., et al., ORNL Intralaboratory Correspondence, May

4, 1977; NBS-Failure Prevention Information Center

Identification Number 397.

[11]

King, R. T., et al . , ORNL Failure Analyses Reports, Oct-Nov.

1977; NBS-Failure Prevention Information Center Identification

Numbers 471 and 491.

[12]

Danyluk, S. and Dragel, G. M., Component Performance and

Failure Analysis, Argonne National Laboratory, April-June,

1977, ANL-77-62.
-16r

[13]

NBS-Failure Prevention Information Center Identification

Number 409.

[14]

Greene, B. N., C. E. Lummus Summary to DOE Newsletter on Materials and Components in Fossil Energy Applications, Dec.

5, 1977; NBS-Failure Prevention Informaion Center

Identification Number 493. [15]

Vandergrift, E., Westinghouse Failure Report to DOE, July 6,

1977; NBS-Failure Prevention Information Center Identification

Number 455 .

[16]

Danyluk, S. and Dragel , G. M., Argonne National Laboratory

Report, ANL-78-6, July-Dee 1977.

[17]

Barney, W. G., University of North Dakota, Letter to DOE

Newsletter on Materials and Components in Fossil Energy

Applications, May 31, 1978.

[18]

MacNab, A., Letter to Institute of Gas Technology, April 2,

1975; NBS-Failure Prevention Information Center Identification

Number 1.

[19]

Metals handbook, Vol . 10, Failure Analysis and Prevention, p.

249, eighth edition, 1975.

[20] Bleakney, H. H., Can. Met. Quart., Vol. 4, p. 13, 1965.

[21] Forty, A. J. and Humble, P., Phil. Mag., Vol. 8, p. 247, 1963. |

[22] McEvily, Jr., A. J. and Bond, A. P., J. Electrochem. Soc., i Vol. 112, p. 131, 1965. I

[23]

Floreen, S. and Kane, R. H., Met Trans. A, Vol. lOA, p. 1745,

Nov. 1979.
Appendix A

Qualitative microprobe analysis was made on the duplex

corrosion products in the cracks on the profile of a Type 310

specimen that was tested in H 2 S plus steam at 5 40 ®C ( 1000®F ) at a strain rate of 10“^/s. Figure A-1 shows the fracture surface and

outside surface (a), the etched cross-section (b), and the cracks in

the unetched profile (c). The corrosion products appear as two

layers on the surface and in the cracks. The qualitative microprobe

analysis was made on the largest crack seen in Fig. A-lc. The area

of the crack was studied with a lithium-drifted silicon Si(Li),

detector. This area is seen in the accompanying target current (TC)

image (Fig. A-2a). The numbered regions in the TC image correspond

to the numbers on the attached energy dispersive spectra (Figs. A-3

and A-4). Spectrum #1 (Fig. A-3) of the dark area in the crack

shows mostly sulfur with some Cr, Mn, Fe, and Ni. These latter four

elements are constituents of the matrix as seen in spectrum #2 (Fig.

A-4). A small Si peak is usually expected in the energy spectra*

and is an artifact of the Si(Li) detector. In this case, a Si peak

is also expected from the matrix as 0.5 percent Si is present in the

steel. The microprobe analysis was unable to determine whether the

Si peak is the artifact or is, in fact, present in the matrix.

An x-ray scan of sulfur (Fig. A-2b) shows the distribution of

this element throughout the crack and along the exterior edge of the

sample. An x-ray scan of oxygen (Fig. A-2c) shows that this element

is found mostly along the interior edge of the crack as well as along the surface of the sample.

The microprobe analysis has revealed that the duplex corrosion

products on the surface of the specimen and in the cracks are mixed

oxides and sulfides with the lighter colored corrosion product next

to the bulk metal, rich in oxygen.
<9

ri f v( '4 nn -JD ,JTI .vfi^w ?

f : b ;

^ y' t‘ kv . 4.3 ,'.t ' r

ir.

J S .

6 ., 6 .;.:i'‘UC :> v> .: ^:. ..n»'..a3

. ans •(..• 2 .,

• '• ' s.tlt ':.f^A, ;. n • 4

> >V' :,* . ' .-(-' . fj

•7 lift J J ft*''H«9 0.0v .; •'.Mjf'W. -ju ••• n f \ } -i -i A 6 .« 3 t+09 qr^i)r|» 9 V ri# p,,i I' I

•

ftlti

C- iqt i '>•'

•

I"! ,7 .

!

'

‘>j "7

J/. t ; f ft i'r*

1 ,>

C> * I'O

' •'•M, 1 ' i

_ r. ,.xM 9 qa

r 1 ^ \ ^ -> y u T ’ fj ,t G 1 . t?' 'll'; (

: ^n7?''9br*z?r- 'S id;-/, •b,MF 9'vfiVlU2 9(t^ '0

“dT /:> :

0 f ^ dr <»y 9 iV artJ' no 9 bftm ? 6 w afa^f^iV!

A r J )

i-'i no’of.f b ft * 1 . ^ ;r

*• - »r

r 1 w .Of -2 6 W ;^ofiia rfJ

' ^if 3 i ^ v' LJta* ;'- o:/e nr 3%? f f ^'t N

.M: -'o ..ee’rt^nJ . :0i 9 fit n: n/ 4:p 0

' 9

' V :t/K'on

•,‘ 7 k- 3.V«d^ J^(T 2 a.. '.viOOi'^ ;/r(r>.y

4

';5*

V 1 i f

' i/ 9 'ifi /(isb '->

1 :: .’1 O'

ig .J jr. J

ft '^fl^ iJo 2 tsdwjn 9 (1 ^

; r> »fiu*ilD9q2 .{A-A Oi

, V» bti 6 ,!:,' I ck; d 1

J *v

y. fJ20 't 2WOd.O;,

rr M g 2 '• ,'. ( 1 T f '!i > n ,r

- ' »j ? .t

*• • :;dt^W^'nOD sH-ii' ' -? <V3 ’ft'a f /* n' DD ! .'.rH|xa \'rl« L'^U ..t -U'J'l \Z f'lbmz A . (

. :. .t : I,. (

>1') ,1 a rf # to 1 4h '»; / -;

•;.,

, 0

. ;

- . (J:r9d? V, * . -

•','^-•-4 f2. 5S . , ill . b ’,(.^7.1 »rft. to f'j'.h) j iie oe

.,'. nJ iriti..-.9'i'; i'2 Jn.a '• -a r > ^ »vA Xl'd-Urn 9rtJ rso.ftft •b»J39q> o/fa

gn ‘ • .''/ :ti.y jifi p,' 9 i d ;• «> >, ''•'

r.is *>d‘0''\(JO’f'5'l\tn ><tf ‘ .‘•f afrij

. M tAm»' r... 'i o£. T^i.ic . ; . 0,1 nr'i.y‘§4 '-rd' ' ^ :‘irt ,•'

-ty. •aV j- 'Vrtiiliaq vj *- >f>'i ;'*;**- od/ 2'wf'd'-M'u.T *

: ;4]i iti. fur to nsoc y^i-x nA

,

. j r ^*" o*' ;o;ry3 o' J '.cooTt o»;f >l-',c;f3 , SJ jwonpuoTflJf jnsfw^fa *>.

'i-'/if ' 6 'fJ rwtVdc ( 3'SA' .n 1 ) «‘-rtVs to n.632 y 6 t-X W,A 5 f 9.

' >6 • r« )ir;t4 ’'ti •,-d.t:to 'lOl

'

‘ / 1

'^f^TTr ' v'f1f-20fll

^ 0 / 2 P :: ;t ,1 ^ ,> r «f ub^ 5 d i J 6 (iS : * 9 i & 3 v » ^ U (I <l T c‘ V A H fl n y 0 “i q 0

3 f in & HT

‘iia.'.'.ff (-/lifi'Tr. idj nf bns. n’st '''(i^ 5'<.* 'to 5y,i;tri;? nrli oq . 1 /

txa'r i3ubo'*n' rfor2o7''''C '' boiofo^ ,ji3f riJ h^t . 'W rtrfftP,

:Oltfj, r bno

,Tis^ ail ''wn/bt

r M . B, 0 . V

'M

.: I ^tcn-r :c

tiOk
Fig. A-1 . Type 310 specimen tested at 540 ®C (1000 ®F) at a strain rate

of 10“°/s in H?S plus steam, (a) SEM of specimen at region

of fracture, (b) Photomicrograph of etched cross-section

near fracture, (c) Photomicrograph of cracks in the unetched

profile.
k’.'

‘t* . i * ^ * • /> -At4^

':/> '*'*

Fig. A-2. (a) Area of target current image for microprobe analysis.

fb) X-ray scan of crack showing sulfur distribution.

(c) X-ray scan of crack showing oxygen distribution.
Fig.

A-3.

Microprobe

analysis

spectrum

of

the

dark

area

within

the

crack.

Area

from

Fig.

A-2a.
Fig.

A-4.

Microprobe

analysis

spectrum

of

the

Type

310

specimen

matrix.

Area

#2

from

Fig.

A-2a.
Table

1.

Alloy

Compositions,

Weight % I

•o •o

0) (U •o T3 •o

r** r— Oi 0> 0) r— 1 U u to to o •»- 1 •!- t u ID oi

4-> Q. o o.

O -rC c C O 00 o^ O. c c

<u o> * C'* «o <0 E

*ou -o o •o x: c *o c 0) c to to to Q) C Oi o o o> o

a; r- 0) to to to r— 0) »— c »— •r- u m 3 to 3 to OJ 4-> ^ 4-> I- oj cr o> o> o> cr 0) 3 3 O 3 T5 c o o O/ c c cr r— *r" r- OJ c s. CO CO CO C L. c o O r10 C OJ < 0> c t. to to ^

0) QJ 0) OJ 4-> 01

m

U

#0--^ Q. CL Q. • p-'' o c 5 li- 5S >> 5S C 2 Li. C fO lj. c o C CL 5 Z h~ 1- 1— ^ Z 2 3: Z ro • <d «Q <o o <o

•*

O 1 (/) lA iO 1.O 1 s. • • u ^ LO •o O <0 to to •o O •o o T3 O •o O CO CO o CO o o o 0) (U Q) -o o o •o o o i o o r— in z E E £ f— 0^ 2 1— o z f— o r— in O 1— z to to to O o Z o r'N z O 00 O 1— Or-'— to in in O r- O 00 ' as O rQ} U. to <o to to to to CO CO 00 CO 00 00 00

VO CM CM

o> 00 VO VO CM o • • • • • • • o C\J 00 m o VO

CVJ CM CM CM r— CM CM

CM a> CMO <T» as

CM in

O VO in In CM

•r* Z CO o a\ o CM o CM CO in

CO o CM ro CO 00 o o O o

z: • • • • * • • o o o o o o o

r«». VO xt‘ 00 CO 3 o O CM o m O • • • • • • • o o o o o o o

•r“ 00

O 1— CO CO o o

(0 CM

HO

X)z VO o • uu

OJo.

00 00 o m in to

o. r— CM !-• p— CM CO o o O o o o o o o • * • • • • * as o o o o o o . o too

•r* SZo CO in

to r— CM o o >> o o o o o o o o o o o o o •o V 0)£o o 00 CM CM as as 4-

•r— VO VO CM S. to • • • • • • • o; o o o o o o o Cl

vn

OJiA 00 r— 00 in CM CO 5s c C'-. 00 VO m as Z • • • • • • r— r— r— r— o o c:fO

0)>

00 in VO VO VO o o o o o o r— o o 4-> • • • 0 • • • • fd o o o o o O o o 4-> •r“

4-> C

to o p* 3

cr to 00 VO

>> o\ o o 1^ VO £ o o 5s O CO CO o CO CO <:r o 0) L

r— c Lu

0) 0) CO 01 QJ 0) o o CL cx. o. O. o. o u

.>> >» < >> 5s c: c *

h- K* H- h- H- I—»

^-4 '«

—’
Table 2 . Gas Compositions ( 1 )

(21 Oxidizing/Sulfidizing Gas' ' (3l Oxidizing/Sulfidizing/Carburizing Gas'

INPUT EQUILIBRIUM INPUT EQUILIBRIUM

latm, 25 ®C latm, 450 “C latm, 600 ®C latm, 25 “C latm, 450 ®C latm, 600 ®C

CO 11.6 1.2 9.2 26.0 1.1 12.5

C02 15.4 24.9 20.6 14,8 22.0 20,0

13.0 16.0 36.3 26.0 12.8 32.7

10.0 12.5 2.9 10.0 11.2 5.5

H

2 S 1 .0 1 .0 0.9 1.0 1 .0 0.9

H^O 49.0 44.4 30.3 22.2 34.3 19.4

C — — — — 17.6 9.0

log P(,^ -28.995 -23.919 -29.026 -24.216

log P- -10.260 -8.878 -10.086 -8.751

log a^ -0.043 -0.288 +0.017 +0.038

The above gas mixtures are two of twelve mixtures being used at Battelle Columbus Laboratories

and Argonne National Laboratory.

( 2 ) ' 'This mixture corresponds to Battelle's "Gas Mixture lA".

(3)'This mixture corresponds to Battelle's "Gas Mixture 3A".

Note: The major difference between the two mixtures is the deposition of carbon from the

oxidizing/sul fidizing/carburizing gas at both temperatures, the oxidizing and

sulfidizing potentials being similar at each temperature.
Table 3. Properties of 310 stainless steel tested

in wet H

2

Sn) and H

2

O/H

2

SV 2 ) at 540 ®C(1000 °F).

Strain Rate, s~^ Gas UTS, KSI, MPa Elongation, % Reduction in Area, %

1.3 „•< 2

u — -

82

» —

566

- -- -9 -

33.8 63.2

7.8 10-5 1 73 504 32.9 55.9

5.5 10-5 2 76 524 33.4 62.8

7.2 10-5 2 68.5 473 22.5 33.1

3.9 10-5 1 70 483 22.9 25.4

3.6 10-5 2 69 476 23J 30.2

1.1 10-5 1 68 469 17.2 18.4

8.4 10-7 2 68 469 18.7 17.5

1.9 10-7 1 -- 9.0 14.4

^Wet H

2

S = H

2

S saturated with water vapor at room temperature.

^H 20/H

2

$ = H

2

S plus steam.

Strain Rate, s“^

Table 4. Properties of 310 S stainless steel tested

in wet H

2

S at 540 °C(1000 ®F).

UTS, KSI, MPa Elonqation. % Reduction in Area, %

1.3 71.5 493 33.6 63.0

3.7 10-5 71.6 494 34.5 62.6

7.3 10-5 69.0 476 35.9 62.3

8.4 10-7 63.1 435 34.8 50.1

1.2 10-7 — 27.0 36.5

Strain Rate, s"^

Table 5. Properties of 347 stainless steel

in wet H

2

S at 540 °C(1000 ®F).

UTS, KSI, MPa Elongation, %

tested

Reduction in Area, %

1.3 78.8 544 17.4 62.0

3.7 10-5 78.1 539 15.5 63.1

7.3 10-5 71 .6 494 15.1 64.3

8.4 10"7 75.6 522 14.5 55.4

8.4 10-7 75.4 520 17.1 61 .4

1.2 10-7 — 8.6 48.8
Table 6. Comparison of Type 310 SS and Type 309 SS in Various Gaseous

Environments at 600 ®C at a Strain Rate of 10”®/s.

Specimen Test Environment Tensile Strength Elongation Reduction

MPa (psi) % in Area, %

310 SS Argon

411 (59,500) 18.7 24,2

310 SS Hel ium 368 (53,400) 19.9 28.8

310 SS 0/S/C^^^ 362 (52,500) 19.9 23.4

309 SS Argon 323 (46,800) 31 .2 57.1

309 SS, ^ Helium 334 (48,400) ZIJ 69.2

309 SS(3) Hel ium 34.3 62.1

309 SS 0/S/c(2) -- -- 36.5 62.7

^Tested at 540 °C.

( 2 ) ' '0/S/C: oxidizing/sulfidizing/carburizing simulated coal gasification environment,

i

^^^Tested at a strain rate of 5 X 10”^/s.
Table 7. Summary of the Fracture Modes for the Main

Environment/Temperature Combinations for

Specimens Tested at 10"^/s.

540 °C 450 °C 600 °C

He H

2

S/H

2

O He 0/S 0/S/C He 0/s 0/s/C

Type 310 ISC^^^ ISC d(2) D D ISC ISC ISC

Type 310 S ISC D D D D ISC ISC ISC

Type 347 D D D D D D sc

Type 309 -- -- -- -- — sc -- sc

Type 446 — — D SC SC sc sc sc

Inconel 800 -- -- D D D sc sc sc

Incoloy 671 — -- D SC SC sc sc sc

^Intergranular secondary cracking.

(2V'Ductile failure.

( 3 ) Path of secondary cracking was not determined.
<.'*11

luWn1o»4 '»OT sfitJ*!'

' , ' ;„.£ Sti

• t.

i'\

^

- *+2'fii.

32

32-

3*2 ...

« ..#

'

5!lf

32

<!'•

t}

K.'

ff^'"

'.H

ttll 'O

'

. ,¥1

Fr' '’>

;£^ .. '•

t.'

Tr -'^•t'.-.

i-^

^s!

I ?<. 2

^

'321

ir.r

^, 3 '•a..' 6 iS :

Jh 9(t)

z m.z

t«i.^«qx.T

€0€«

8 ^^ aq^T

c<*j 1 'q^fli^caylCtENB 'tx'

.•fti fW'tofosnl';

...;f.-:'.

•‘ 3

'S

13 X^ibno39f fafunii^TSJnr' *

rr.

‘ *3

': m^.

^••1!; M%

M- .S-tufU^ »ft35U(»?*^ I

, bart^ini^ftb $on 46Wf9#jf>a'!3 t'^SbrwMa ^ 35 r

tft" IS

•.Mw,i

'??;'

''J'it;:

.V-J

( *

'

.. 'v'.i

'W''* It

urty

r’m’
% REDUCTION IN

CROSS SECTIONAL

AREA

. , A C

STRAIN RATE

Fig. 1. Schematic representation of typical results obtained from the

application of the SSRT to the study of SCC in aqueous media.

The interpretation of Regions A, B and C is discussed in the

text.
I

too fjLtn

Type 309, 250 X

*|!» 0

Type 310, 250 X Type 310 S, 500 X

100 ftm 100 /im 100 /JLm

Type 347, 250 X Type 446, 250 X Incoloy 800, 250 X

Inconel 671 , 250 X

Fig. 2. Microstructures of test alloys in the as-received condition.
The Slow Strain Rate

Stress Corrosion Testing Cell

mV Outputs

T

jka

i

Load

Cell

LVDT t

(Extensometer

)

X

9

S

o

oS

Gas In mV Outputs

from 3 other cells

Slow

Strain Rate

Scanner DMM

Time

Thermocouple to

furnace controller

-Test specimen

Programmable

Calculator

Mag. Tape or Disc — Digitai Plotter

Fig. 3. A schematic representation of the slow strain rate testing facilities.
TYPE

310

o o o

o o o

^ c*> <M

* SS3U1S

O O O

O O

O

%o

O

om

Fig.

4.

Effect

of

strain

rate

on

stress-strain

curves

of

Type

310

specimens

tested

in

H

2

O/H2S

at

540

°C.
Ductility

as

reduction

in

area

versus

strain

rate

for

Type

310

specimens

tested

in

gaseous

HpO/H^S

and

He

at

540

®C

(1000

®F).
Fig. 6. Scanning electron micrographs indicating the effect of

strain rate (e) on the fracture of Type 310 specimens when

tested in H

2 O/H

2

S at 540 °C (1000 °F).
Dry Purified He

Fig. 7 . Cracking of Type 310 specimens in various "inert” environments

when tested at 540 °C (1000 °F) at a strain rate of 10”®/s.

Original magnification 7 X.

Torr
Fig. 8. Scanning electron micrographs of a Type 310 specimen tested in

H 2 at 540 ®C at a strain rate of 10“^/s, showing the primary

fracture and numerous secondary intergranular cracks (above),

and the zone of intergranular failure on the primary fracture

surface (below).
Type

310

specimen

tested

in

air

at

815

®C

(1500

°F)

ata

strain

rati

of

10"^/s.

(a)

Photomicrograph

of

the

fractured

soecimen.

(b)

Sea

electron

micrograph

at

the

region

of

fracture,

(c)

Photomicrograph

the

sectioned

specimen

near

the

fracture.
(b)

Fig. 10. Scanning electron micrograph and photomicrograph of Type 310

specimen showing the ductile fracture and partially sensitized

grain boundaries after testing in He at 370 °C (700 °F) at a strain rate of 10"^/s.
i

I

I

i

Fig. 1

(b)

. Scanning electronmicrograph and photomicrograph of Type 310

specimen showing the ductile fracture and partially sensitized

grain boundaries after testing in H

2

at 450 ®C (840 °F) at a strain rate of 10"^/s,

i
700 o O O O O

o O o

VO un ro CM

^dl/V ‘ SSBdlS

O O

O

Fig.

12.

Stress-strain

curves

for

Type

310

specimens

showing

the

effect

of

temperature

when

tested

in

dry

He

(passed

through

inert

gas

purifier)

ata

strain

rate

of

8.43 X

10"^/s.
310

SS

(Ddi^) ‘ss3ais

I

u

Fig.

13.

Stress-strain

curves

for

Type

310

specimens

tested

at

450

°C

(840

®F)

and

600

°C

plOO

°F)

in

He

and

in

oxidizing/sulfidizing

and

oxidizing/sulfidizing/carburizing

coal

gasification

environments

ata

strain

rate

of

1

X

10"^/s.
Q.

(O

S-o»o

i- • O O)

•r- i- E 3

O 4-> •M O

o «e f s. Q. tj-

(0 O

c

o • ‘r-

(/) CD

OJ CO iIo 0) r— xzp X • •P 0)

Id i.=3

«+- x: 4J o o. u

Id Id

•r— <u i- iin p CD*P

a. Id O

&. S. (U o u x: o c •r- CO E M CD Id t.

C«* • i. c Id 00 h- O (U

-—CO in s- c

« , •p

Id u c

s: <U 03 p •- E

CM C CO Id <U «r- O o • o

CO ‘I— o CD 0)

, +J CO 0 C Cl

Id , •t- to CD O c

c LO C "O

oo o Id 03 h- I- <c o c

=} LU q2 •P oo o

ro "r- —' 4-> (U U

<U

in

O) c•r- •o

O)

(L) I-

(D U O

O) <U +J CLx:

(/) o. C (O

0> T3 S- E 0) cn

•I- s- o

U 3 S- <U -•-> U

Q. O -r-

(/) Id E

s- o O <4- +j r— O

CO <u x:

x: Q0)c. ^ >>»»- o

I— o —
•

<u

i-3

4-> U

OJ (O

i- i- Z3 M4-> O 0)

C7> • n) C (A s- +-> •1— N u> L.

•r-l «4- (O o o O 0)c

«4- • C

r- X C O C 3 O) <U M r— E E

I "r- <D 'r- cno- u S- (J C O 01 0>

•f*> CL O

N CD to x: </) 1- +-> +-> T3 (O -a T5

•r- t. <U 4-> <LI X (. (O C

O C 3 O

tA •I- +J -C •!- a. (U « U 0--4-^ o

x: 1. (0 ra u

+» +J S- l. OJ o </) 4- 01 W

CM c o A •t- <d (u t- 0) x: u f 00 T5 4-> 4-> T- 4-> +J4-4- 0) «0 E

O) O O c o

CL ^ ^ 0> O O S «3- 1— -4-> x: s. ^ • • O CL+-> Q. r— in to c LO fd u m

00 CO lO 0) cl- £. a s- to E o>t— cn

1 1

1

c

•r- +J o <u o

o to i- i. <u u o> u

Q. +-> •!- Ctto c E •«- E

o O) o c o

•r" O E C -t-» •L» 1— c o «o o

<e CO o XI o x: w S- Q- OO CL c <U *1- 00 o Ql

h” ^ < >> C (O Xi u

=> LU o; hLn

t3>

f
- - k'

.. .- ,C ^f''^U- . .'* :~r -7^:^

"^ '#

H

'"* -»v'' ’

•*vjrt,. ^" ***^ - *'^'4 ,...• 

00

lO

<a o0) 4J

4J

C

«/> 0>

0>

&.3

+J • O

0) (O

t- s- 3 «4- MU O) 014- lO ^ C O S- -M

•r- 4- N <U S.

•1- -t-> 4- <0 o te O 0)

•r- t. c

4- • c

1—

C c o c 3 *1- a> •r- <u

(/) <o E C7> E 1 L. •r- <U ‘r- oi +-> U L. U C (/> o <u

•r- a. 0) Q- N (O (/) f i/i •T— +j o O T3

•f— <o Oi 4-> <U X (. (O C

to o o 3 O

o. o +J x: -I- 0> U CL +J JZ o Id (d a O 4-> in t. S. 0) o 4- 0> </l c o m 1- 4-> 0) t- o o cu

•r- +J

e: 4-O

Qu ^ o Z l£> CSJ •!-> e x: s- f • • o Q.-4-1 O.

00 ID

O c t- Idu Id Cl CO VO o; f- t_ 0) s- m1 1 1 E >

•rC U 0)

0)O. Ol

Oli— Ol O 0) o u I- O Ol u • 'r- C c CO C CO E ••- E o •f— >>. O c O O N U3 -»-> C +J 4J 1— T- 1 O Id O

Id CO i. o x:

u x:

Olc 3

01 X) 1— CL to c-

(/) o CL tX *—“—^ **—

h— p” < >> Id Id -O

u = Lu q: »- o r— 'V—

U3

O)

<a

J
Fig.

17.

Type

310

specimen

tested

in

dry

He

at

600

®C

ata

strain

rate

of

1

x

10"®/s.

(a)

Photomicrograph

of

fractured

specimen.

(b)

Scanning

electron

electron

micrograph

at

the

region

of

fracture.

(c)

Photomicrograph

of

the

sectioned

specimen

near

the

fracture.
vta. ooCOoLT>

<e o.£ o %o

• • ^ rCO r- CM

4-> <ocnc

in o

r- < ra uj o:

>0

Fig.

18.

Type

310

specimen

tested

in

the

oxidizing-sulfidizing

environment

at

600

®C

ata

strain

rate

of1

X

lO’^/s.

(a)

Photomicrograph

of

fractured

specimen,

(b)

Scanning

electron

micrograph

at

the

region

of

fracture,

(c)

Photograph

of

the

sectioned

specimen

near

the

fracture.
1JI

I'jJIIi iI

O)

s-34-> • O

<U rd

i- s-

=3 M- I U (U cn«4- »d x: c o s~ *-> •r— u- N <U i- •1- -M U- ns T3 la O <u

•r- J_ c »4- • c 1— C c o c 3 •!- <u •»- <u

(/) fO E CD E 1 s- •f— aj •!— 0) 4-» O S- o „ C (/) (U (U

•r* •r“ CL

O Q.

(/)

N (d to -C t/> Q. •1“ •4-> T3 4-> o -o O •t- «o <U 4-> O O X S- rs C

LD o o 3 O M o +-> x: T-

<VJ <u

O CL 4-> LD x: o ns ns u

+J i- s- <u VO 4- CT to

nj c: o

Q. ^ •r- 4-> 0) L. (U 2: o> (d x: o x: • • •o +J *r- +-> <VI <T> CO 0) <M . E . I— CM •«-> C »- 4_ CO 1/) O) o c o 0) E o 1 1 1 C x: 1. x: 1 1 1 O Q.-t-> CL C S- <d o <d c <U *1- S- 0) s- o E > OOi— oi

•r* • 1- c 0 0)0

•fJ

a O) S- S- Id (U o o> o

C3> ol cn • •rC •!— c (/) C U) E E

(/) o •r- \ o c o

t— r— < O NvO +J

C 4-> rs LU t*“ ‘r- 1 o Id o

CO (.ox: ox: 3 1—

q; X)

CL OO CL

O. SX

>» «d fo jQ

a

J—

O r— o <J»

D>
TYPE

310S

,

540

o

00

ON

X

1

I I

0>

1

o o o

40 ^ CM

(%)*V3dV Nl NOIlOnaBd

ICO

LU

K

Z

<

K

H*

(/)

Fig.

20.

Ductility

as

reduction

in

area

versus

strain

rate

for

Type

31

OS

specimens

tested

in

gaseous

H

2

O/H2S

and

He

at

540

°C

(1000

®F).

Type

310

curve

is

shown

for

comparison.
3I0S

SS

(DdIM) *SS3dlS

Fig.

21.

Stress-strain

curves

for

310S

steel

tested

at

450

°C

(840

®F)

and

600

°C

(1100

®F)

in

He

and

in

oxidizing/sulfidizing

and

oxidizing/

sulfidizing/carburizing

coal

gasification

environments

ata

strain

ira+o

n-f

1

Y

in“6/c
1 

!II

V)o. oo

in

Ou ^ S OM^• • 00 00 CO I— ro in

in co

<acnc

C/l o 3 UJ ^ c «-

•I- o

(d

S- "O c

4-> (U

O

(/) t-3 O'

<0 4-> a; u u

4J «3

<d i. o) JC O +J O 0) ^ +J o +J re in

ref 4- x: o c

•P <c (O -c t. o. c O 10 c z t- t. cn L C 0 *r

•I- t. E u

"O *rC

0> E C P O i

«rt P +

0)

O 1 P £ < O. r- I— <

0) Id ( P >— 1 W> ••i «/> • I Ut V> I 0) *««. < r—VO 1 C I •1-0^

rO rJ P •> W X

(/) r- O

C OJ 0) r-p<Ut.tCO O E 3 3

•1^ P P

0) <U

O (->

U

O.P 01 (O Id >> Idi. Crt p P

CM

CM

cn

ID)

oCanillny

cicuuivm 4

,u^;

(c)

Photomicrograph

of

the

sectioned

specimen

near

the
Ii!1i

ll

IIIIji

too. ooCMA U)

>o Q. ^ ^ z: io I— • • o» 00 m I— CO CD

LO 1 (U 0>+J c Id

•r— s- N

•r— c

-o •r—Id X s- o •<-> to

O) JZ Id +J

+J c Id o TD 0

(U

4->

O

W ir> <u

•4-> Id

o;

<u -4-i 4-> c

(rt 0)E

to c

to o

(U S-

•r“ c >

fZ Id <u

OJo

<ua.

to o(Uu

(d

i. M-

<u JZ

«-o

o.

(d

i-cn • o

LO &.

's.

O

to OVO »r- c Cl E o C/J o o

•r—

O IM r- -M

+-> 1— o

Id CO T3

X x:

Ol •I— Q. c O) 4- 1—

oo o Q.I—

h- 1— < >> 3 4- Id zo LU OC 1— to O '

co

CM

o>

Id

(b)

Scanning

electron

micrograph

at

the

region

of

fracture.

(c)

Photomicrograph

of

the

sectioned

specimen

near

the

fracture.
COQ. O

CL ^ s: 00• • CO 00 r- CO CO

in I le c»c o •r- r- • N (U

•I—

X ^ o 3

•I- r-* -M 4- O

r— 4- <d 3 0 ,S- w 4- I 0) D1 

- c <d o

•I- s- N • C

•I- c c o ^ *r- <U

*0 E 01

X L. ‘I-* 0) 0 4J O t.

I/) 0) 01 0. 0) x: fo «o .c

+J

•p *o c «e 0) P

f- (. <d o 3 ^ o P x:

0)

u o P o <e (0 M to SL s. 0) oO- 4- O P o P 0) L

>» « x: (J 0) P •!" 0) p . E P C P

(/) 0) o c

(/> ^ x: s.

(/>

O 0.4- 0) <0 (. t—• *r" L> 0 c > cni-

•rC

O 0

<d 0) t- p o e

«/) CT> fC CO •!- o c O N P C r— •!— O fl CO 1. x: t 3 O. (/ 0) X

Q.

>t le <e .< l_ o —

'O' CM

o> I i » <

(c)

Photomicrograph

of

the

sectioned

specimen

near

the

fracture.
(U

i. 4-> a

<o

O s- -•-> o 4-

sO 4- to O O 0^ VO c • c: c: o c

<d a» •»- <i» E cn E

<u •r- 01 *r- nz U S- O

01 01 >> Q. 01 O.

i- 1/) ^ </) o •M O "O c 01 -M 01 » S- (d C

•r“ 3 O

Ui T3 -*-> JZ *1- a. 0) • U CL-M

+-> «/) Id <d o o W S- L. 0) o (Uu> 4- O) C/> •Ml O o 01 t. 01 CO f— 1— sz u sz

VO 0) •4-> T- -M

<UX E

•M 4- 4-

Id (/> 1—

O

C

O

o. ^ O

s: 00

W 4- JZ ^ • • (/) O 0.-M Q. r— C\J <U Id u Id CO CO ^ e— <U 1. 01 s- C -M 0>I— o>

to

O 01 o I 1 1 to i- s- s- 1 1 1 •M o o> o W c •r- C •!- c •r— E *r- E o GO «d o c o •1— O S- •M C -M

4-> r— -M

O Id

O

(d CO (A JZU JCZ C7> Q- GO Q. c <U (d GO O o. h- 1— «C >>•»-> ^ a

=> LJ QC H* «d

Ln

c\j !I

o>

cd t

(c)

Photomicrograph

of

the

sectioned

specimen

near

the

fracture.
I

o>c

N

•r" •o

3 (/) U> \I u> ON

C O •r— I— N

•r- X o•r* I— X

o *t-o

0) x: <u »> +*

lO C L.

(/> Q.

oO

"O f—

0> R>

s.

«/) -M

<U {/) IT) p

<0

•O' r“

in 0) P

0) <e p

<o </} o

o. ^ ^ o s: 00 in

. • in o

lO CM CO 0) O Cs. CO ^ I—

CO

1 II

C

t- P

<o <o pto P

c

o

•r“ •P

10o>C

00 o _ O LU ^

c

00 a o E

I— c

CO o

i. <U *

1-

a. >

*= I— oj

UD

CM

o>

•f" u.

(aj

Photomicrograph

of

the

fractured

specimen.

(b)

Scanning

electron

micrograph

at

the

region

of

fracture.

(c)

Photomicrograph

of

the

sectioned

specimen

near

the

fracture.
IIi

i!if

i!I1

'S- ‘H I

tAQ. O

rx. 00

fO Q.S ro 00 • • JO to o CO

CO CO CO

00 co

•I— 4J

<aCDc

to o

I- I— c 13 LU Ct:

fd

Fig.

27,

Type

31

OS

stainless

steel

tested

in

the

oxidizing-sulfidi

zingcarburizing

environment

at

600

®C

ata

strain

rate

of1x

10

®/s.

(a)

Photomicrograph

of

the

fractured

specimen.

(b)

Scanning

electron

micrograph

at

the

region

of

fracture.

(c)

Photomicrograph

of

the

sectioned

specimen.
o

00 o

to

o o o

CM

(%)*V3dV Nl NOIlOnOBd

Io

IQ

h"

(/)

Fig.

28.

Ductility

as

reduction

in

area

versus

strain

rate

for

Type

347

specimens

tested

in

gaseous

H2

O/H2

S

and

He

at

540

®C

(1000

®F).

Type

310

curve

is

shown

for

comparison.
(Ddl^) ‘SS3dlS

Fig.

29.

Stress-strain

curves

for

Type

347

specimens

tested

at

450

®C

(840

°F)

and

600

°C

(1100

°F)

in

He

and

in

oxidizing/sulfidizing

and

oxidizing/sulfidizing/

carburizing

coal

gasification

environments

at

a

strain

rate

of

1

X

10-^/s.
(/) Q.

OoCO

A

CM

00

10 P. ^ S 00 CM

• • 00 00 U)

VO I— iO

in

c

o

•p

<0

cr> c

(/) o

H- r— ^ :o ui ci:

c

«r«le

s- p

(/)

<0 plO ooo

in

'O’ pto

0)

oOJ p«/) «p

0)

0>

«/l in

(/) OJ

10 p</»

r>. CO

0)a

>

oCO

at

Id

rate

of

t

X

10“6/s.

(a)

Photomicrograph

of

the

fractured

specimen,

(b)

Scanning

electron

micrograph

at

the

region

of

fracture,

(c)

Photomicrograph

of

the

sectioned

specimen

near

the

fracture.
ll

‘I

ll

ll I

(O a.

:e ^ ^ O «M • • CTi O ir> I— vD

c.o

•r* +J

(0cnc

CO o 3 UJ ^

cncN

•r“ XJ

•r— Ct- • I— CO 3

10V£> I I cn oC I— N X •I— •O r- X «- o o

(U <u jr +J +* <o

i.

cnc•1“ I c o C +J

fO o • a •<= <u CO iO. i-3

+J X> U CJ — <o

sC (U OJ <U S- JC E 3

•r- +J u u ^

(U <e n) a. t_ 0) <n M- c

"O *- c

QJ

O O) i. E o «o

0) i. +j 4J

to to

OJ

4-> ns I— +* 0) ns

(U

4->

Ocn o

</) oto to

OJ ^

*C +j

•I— «o

lO +j <4-> to c

a;

r>. E ^ c

CO o

u. 0) *1-

Ol >

>> c c

+J o o O ‘r- <U

ns cn Q. ^ (U (O

«t- i- o (U <L) 01 x: f c

4-> •!->

O

tl- »> +J o ns u

os f J= to Q. CL

ns ns a;

s- s- x:

cn os !-> o o

j- s- «+- u u o

tf— E E -c O O.

4-> c (d o o s- ^ S_ CD

Q. -M

O ^ U S- 0)0

ns r— •!“
0>

s. 1 3

CT> +J C • o

•1— o; 40 N t. i~

•r” 3 *- o • •I— (/) U 0> M- ^ 40 sz r— ID t. •«-» 31 Ml/> O u 1 r— 4- 40 o» O 0) C X c

•1— • c N r- c o c

•»“ 0) *4- OJ O «4- E cn E •1— O 01 •*“ X U L. u o 0> 0) 0)

-*-> CL O) o.

(U 40 iA JZ V» x: fc. 4-> "O ; 0) •o , ^ c t" k. 40 c

•r“ •4- 40 3 O

</)

k 4-> f T*

CL *0 •!->U CL4-»

0) (4) 40 40

U

O 4->

k

k 0) o l/> 40 4- 0> (/) ir> 0) O

«% 4^ 4-> 0)

k «

ir> 40 JC

U J= 00 1— 4J •»- 4-» 01 <»-> . E , 0) c 4- *k

40 4-> 0)O

CO

Ol ^ ^ ME

O

s: Bf kx; • • M O 0L4i> O. O CO <Ti M k 10 U 40

CT> 1— lO <U *4-

k 0»

k

U) 1— > 0>f” o> co

+J

<oO)c

00 oI llI CC

CC

O 0) o

•r- 01 L. 1- 40 U O) U

4J D>**“

C ‘rN c •»> ^ O lO o

CO L. f U f 3 CL to O.

0)O.

>, 40 40 JQ

U

tCM

CO . - I V J - ) uIj I1I
nkI

i|I1 ' -X-, - * _,*'-<iii'*-^ ^.T>^

"'-V'

<-> "- fi!- - ~ - \ *

;.fr

.• ' ' V5 . j.

'i '<;^. . 4,” %. '4 •»

'•'A'

«o XJ

t. Oi

(/> Z3

•fj «o o

<0

4-> l-

•o •- CJ Q> O f--> OO «-

VO

O

•!-> x:

fO o.A

•r* Oi ii/» zn D>

CL o o C 1.

•r- o oCO XJ E

Oi

O

LO

M +J VO (/> O ^ <u x:

«9

Cl.

4-> O- < £ V3 Oi <o

<«3- CVJ 0) • • •M

m

n CM to ^ r— vn • 1 1 1 c

to to

to0X0

f— 1 C O ‘ o •r- r—

•r” « M 4J

X

«0 to

C7> C 1/) o *0- »«- H- r— < ro o

=3 LU OC

0*a

Q. 4-> >> lO 1— fc. • CO

CO

CO

•r*

Lispecimen,

(b)

Scanning

electron

micrograph

at

the

region

of

fracture,

(c)

Photomicrograph

of

the

sectioned

specimen

near

the

fracture.
<u

OI -M O. f le <a •M 1.

4-> cn c c o •»- flj !• E U

4JU

C I (O o o u

i- 4J »-

•M O

u x: o>

(U Cl. x: f— +J

OJ.

in O C •f U k

o. e o E cnw 10 k 5 c at o O f- 44 f- C o O > Q c • r«. 13 c: x: c at k

m at a. 10 k at

4-» USE ID 10 4-» *r- C 10 u u

•o 10 at

10 0) N 3 k a.

O. 44 T- wi*- in s: ^ in k • 00 **> at 3 in *4- TO

• • CM 00 ^ r— to

I I I

<a

C7> c

(O o

H* < 3 UJ £

kco e c

« • At C O

at u o E o

at I r- •»- T- 4J

4-» cn u cn u

in c X at at at c. 1. in

in

at at *o £ x:

OJ 4-> 4-1 t.3 4-» «4- 44 10 O U

<0 x: x: u Q. o.

*4- lO <o at cn

x: o o

4-> t. &. u u

in N r—

in •»“

, 0) T3 H- r-^ O

C ‘4- f- r— 01

lO 3 4-t

4-> M 10 in I k

o>C C ^ ‘r- •»“ CO N <0

•*“ k

at Tt 4-* cx'i- in >» X

»— O 10 O E E

I

'

I

| I

i

I

V'l

I

It
I

cn oi c c

•r— •!— I N CO •r- C +J •O rO O

•IO ^ M- • 00 Cl. I— 1/1 3

VOVO .O o • 1 1 — (U DIO S_ C (— 3

•r- » . +J N X C 0) U

•I- 01 S- rd T3 1— E 3 S-

•r~ •r- . 1- +J Vj_

</)

X

U

O

O.

O

O 01 (O 01

O

Q. S- J=

01 01 (/) 4-

O jC +J LD •M lO -O «4- 1. A &. 01 o <a VO C S. 01 VD •I- C 3 C C

•. . •1- -M

O

(0 •o « VJ •!- c

0) i- (0 D1 01 cu -t-> -l-> JL 01 E z ^ ^ w VO 4- i. 't- uo o 01 u o • • 4-> Id 01 01 01 VO <ct VO x: o. ^ r- «:1- 1— +-> -V-J +J 1/1 1 1 1 c

01 Id

01 4- 4-» "O o o Id 01

VO o c

.c f o o (/) O Dl D-'i—

•r— VO

O Id Id 4-> +> 01 VO t. (. u

(O r— Dl Dl 01 oi C •«-> O O VO c •1- Id J- s- 00 o id vj <j 01 +J +J ^ (O c E E -!-> O) O

r>. E -MC

C

OO

CO o .c s_ S- Q- +j

<U *1-

O

Q. > ^ <U >> C (T3 I—

I— <U '—O

graph

of

the

sectioned

specimen

near

the

fracture.
700

toc0) E

•r" U

OlQ.

to

CO • o o o c« oo CTi to OCO +J

•a to0) <u CL 3; H- C 0 «/> ino

<u I > O 1. t— 3U 4-O c

•r- Oj

•O 4J 1. <o

-•-> L. to1 c

</> •!“ to «

O) t- 1- •<->

•!-> to

to

(O cO +J

(O R>

•t—i. T3

(O OJ CL4-> EO 0) O

to

COo
I!1Ii

M-O

<U

-t-> fO

s-c

•r- •F» in (d CL i4-> o t/1 o •ac

00 «0 oo

<a a. o

s: ^ ^CM CO CO cr. +J CO CO LO fO 1 1 i a; 1 1 1 3= c C o

•r“ +> •o

ra <u

tJI c w

00 o 0) H* r— < +J =3 LU c

<uE

f—u

(UQ

CO

k 1X

10"^/s.

(a)

Photomicrograph

of

fractured

specimen

(5

X).

(b)

SEM

at

the

region

of

fracture

(20

X).

(c)

SEM

of

fractured

surface

near

edge

(500

X).
(a)

(b)

Fig. 38, Microstructure of Type 309 stainless steel, (a) Islands of

ferrite in austenite matrix, as-received condition, (b) Islands

of ferrite transformed to mixed ferrite and carbides, which were

indentified by chemical etchants, after being tested at 500 ®C

in He at a strain rate of 10-6/s.
700r,

446

SS o O o o O o O o o O

CD in

(OdIN)

ro *SS3dlS

CM

O

1^O

CDo

inoo

lOo

CMOO Z<

oc1“

cn

Fig.

39.

Stress-strain

curves

for

Type

446

specimens

tested

at

450

°C

(840

°F)

and

600

®C

(1100

®F)

in

He

and

in

oxidizing/sulfidlzing

and

oxidizing/

sulfidizing/carburizing

coal

gasification

environments

ata

strain

rate
0) C»f C

•r-C 4- C O

<e 4- O O OO Q-

•e

t. +J XJ cno

t- 1.u C • T-

•V

C E

(d 0) o

t- E -M

4J fO

l/t

u0) a.

lO o.

•r- in

l/l *» o

O. « 'O'—

V O o t. o 0 3* « out.

LO

m lo 3

00 t- 4-» 4- U

** to

10 to o %. a. SI 4-

Oi -4^ «n o 3= . 4- ^ • « 4- O

00 rs.

C

O

m ^ u> 1 1 1

•r- e

SL

O *0 Q.t- O to XJt •M t. 0» ' c VI Ot t. o V O

•f— -«-> 1. 0>

4->U f

<0 1— •!- 4J o» 0) E c 01 O -«-* CO o +J +J «3 err < (A O

(/) Q. O.

(/) lO

V, I— (O oi C W o

L. « U 4J •ti/> </) E —

(OlO c ^ I o O (. r— +-> 0) u

O.X 01 >» *“

K- r- O) O

CT>

sectioned

specimen

near

the

fracture.
<u

4-> 3 C •4->

u (U 4-

O E d) o ro c x: s- o -•-> c 4-

i- o

•I- 4- -I- <U > O C <U +-> OJ ^ l- Q. i- cn la <u la c i_ x: O)

•I- cn+J c N o

•I- j_ +-> c o o «3 <i> ^

4- E -C •!-

*r~ r— o Q.

a

CO 3 -M iQ <U Q. W O S- Q.

cn CO

O c^o. o C S- "O •1-^0 0)

fsl (O •(-C o E O

00 T3 •!- 1- C +-> X • o o

(O

O (O S- <u D. CO s: ^ OKO U

CO ^ x: 1 0)0)

CVJ • • +j o I— x:

CO CT> r— r— O) +J

Lf> r— CD 1 1 1 c

•IX cn4-

c: o

T3 1— •(- 0) c x:

C +J 4-

C Q. o 10 O (O (O

0)

u s4-> +J o; 00 CT) (0 +J o

o» r— (O i- c o; s- X3 u

(/) o 0) h“ r— < +j c E

=3 UJ q: to

O

(O • +-> to $- c o

to 0) x:

O) to E Oo c « o

•r- <U

O

«0 4-> +J (O CO

CO

O T3 • CO O <U (U

S- J-

<clO 3 3

in 4-> 4-> (U O O

Ol (0(0

>>+J S- S- I— lO 4- 4-

O)

to

‘S

r, (\
ina. ooC\J CO

CO

(0 o.

s: ^ o o

r— 00

IT) CM in co

<ecnc

tn o _

=) uj ^q::

in lOI cno c

sz

a.

le

s-cnO

D1

O

C •!-

•f” E N X C O

•IC 4-> -a I— »o o o x:

1*- If- CO Cl. r— O 3

in cu ^ 4-> C7> «0 C i-

•r"N

C

JO

O

•o (O E •I— i- ’I— X 4-> O o u> 0)o.

<u «o (O f

-M -O « 0) c

•rOO T3

(U

O •P in

in ^<u P -P 0) 0)

«a f x:

I—p P

i.3PU

R>

L.

O)

s- • 3 O) P P O 3

<0 PO P «

&. P Po

0)

C JC O p

<U P

O) c P p a; o

in

BC JC

in o CL

in &.

O) T- I— > c c

(d p cn*r-

(o c E

•rO

l£>

N P ^•1—0 ^ J- x: 3 a.

OJ XI

Q.

>> (O <d

o> i~ (U lO

t- <ucc

0)Eu

(UQ.

o. in

tdP T3

O) 0) O P

SO U Po

<u

in

Q) co

&. pO

p

(U I—

p

CM

CT> u.
IIiii € o

(/) Q. OO

CO

CO

(/> co

40

<oo> co

Ul <c

oi

C7> c

•p—C «f- c o

ra

M- o x: O C/) Q.

rtJ <U p-' S- 40 ^t0'~' o

s- s-o

(0 0)0

t- E 40

40 *1- o

</)

O -c

O) Q.

(O Q-

«/> •—

40

a

ro o O S- O 3 • 40 (U o o $- 0(0 0

VO S. 40

«l_ <J • 4-> (O O

(O O) s- s- ^ U- 3

0)40 4J m «4- o

4-

O (O CO s-

•IC 4- ^ o

•o Q-"|- <U O lO O.C

4->

C 0) -M

W

C71 S- 0) O t4-> t- OJ 10 U ^ O

r— -p- 40C

0) E

O)

O 4->

C

4-^ 4-> (O (U CO O E

o: o: *p- tO D. Q. O

to (O O)Q. I— (O CO to C —' o

•I- S- T3

(O

U O) 4J • -I- C

to to E O•(“ toto C 4-> ^ I 00 «sf O S- O) p— 4-> to

O)

U

Q.X 0) O) >, I— ^

I— r— <U 4->

CO

O)
+J

<d

C7» c

00 o

+Jc

<uE a> c JZ o

s0)

S-3

-»-> M- O O n3S- C M- O

•r- <U cnx:

OJ +J

&-

s- (U (O x: <u +J c > o c

(U -c:Q.

CT> <0 c i.

•r- cn N O

•I- i- +J c

•o

u «o <u

•r- •»- E

M- E -

r—

O 3 4-> tA O

Q.

U

(O O)Q.

to cn o) Q. end- O c i- -o O •I- ^ o <u O N «o T- c

00 E o n o

un •rC 4-> X • O O o to L. a>

Vs. to

(O (UtO

u

o. ^ x: 1 0) <u s: 4J O r- x:

!». cn 1— a» 4-» • • c O «d- 00 •r- X cn*+- 1— CO CO 1 1 1 c o

T3 r— -r- 0) ex:

•4-> (|-

C O.

to o <o <0 c <u o u o +j <u CO cn

+J o

I— lO

0) S- -o

O) +j c

l/> "r-ra

(/) &.

to 4-> 0) (O "c td

uo• +J c o

(U ^E O.

(U

u

<o -•-> o-«

4-> (0 (O to 0-0 • to O O)

'!»• $- O 3

+J

0) to

u

o. <a

>>-•-> Jfracture
v> . I

JZ

0.

<a

V.CDO

1. CD CD cn o C t— C •!- t- T- E N X C O

•I- c •»-> a *— ro o

•I— o -C

*- M- t/0 O. ^ o 3 —

U) OJ ^ o * cn lo c tID N c C O) Cl •r- *#— O) S- TO «} E 3 O •r- L. •r- +J X +J u u

CM

O <D 0> R3 CL L. CO <L) lO CD 4-

CM JC

4-> +J T3 4-

«a

OO

«o c (. o. •r- <_) 3 t= S. ^ O +J O

cn ro T3

O •»“ oCO CTl CO r— ^ 00 co

(Ocnc

cn o I

33 UJ cc:

<0

0) o lo cn

4->

O i. 0)

V> CO 4- s_ OJ

OJ <u I JZ JZ

+j 4J

0^ 4-> Ol C 4- -*-> •M 0) M Ec

U)

O

tn L. <U *r- «— > c c

•I- 0) (O +J CD

ID c O iO

C. Q.

R3 la

i- t- CD CD o o

L. S- u u

CO

N ^ Tzs <U JO o. t. >> <0 H- o E £ o

4-> tz o o f w

O. +J — u» OJ fO I

oi of

the

sectioned

specimen

near

the

fracture.
Fig. 46. In 800 specimen tested at 540 ®C in wet H2S at strain rate of

1.7 X 10"'/s showing large amount of surface scale and remaining

metal
IN

800

i L

O

lO

o

o

o

o

r^ o

o

o

o

lO

o

o

'it o

o

ro o

o

CVi o

O

o

(DdlAI) ‘SS3dlS

Fig.

47.

Stress-strain

curves

for

Incoloy

800

tested

at

450

®C

(840

®F)

and

600

®C

(1100

®F)

in

He

and

in

oxidizing/sulfidizing

and

oxidizing/sul

fidizing/carburizing

coal

gasification

environments

ata

strain

rate

of

1

X

10"^/s.
KO

Ior- COC X •!-c

*— f= H- u

0 t/0

01 ^4-> XI

<0

1/5 o. o

CSJ VO

r*>.

<0 CL

Sl n r-

^3 * * <\j r«. cNi in CO r*.

c

o

•f— 4-> (OO)

c m o

I— I— < =3 ui ^

« 01 U E 4-> *r- M O

0) <o O.

in « *o0) O k

O 3*J O U m IQ

+J

IQ 01 « 4-> c o

•r- o CL

0) IQ

•«-> k

V) oi

01 o

•M k

U oO E

00 o+J >> o

o x: I— C- o

C IQ

electron

micrograph

at

the

region

of

fracture,

(c)

Photomicrograph

of

the

sectioned

specimen

near

the

fracture.
!

rt» o x>

4-> <u

-«-> x: (o c CO. o

<i) rtj x; *F- E c 0.4-> c cn (t3 u o o t- <u C U C71 .1-0 0 > T- C <U c E o .C

•r" <U

O 4J

tn E , o. cn O **- O c x: c o •1- o. o o N ex:

cn 4-> O. « o «J U ro 00 .r->-' 0) e

r*«. »- cn •— QJ O

<o 3 • e

1/1 </) cn

u

o.

C •!- s: axo «f- E

U3 00 Cl CO •r- O C

«5T CM to

N 1— lO

O

to CO VD r- ox: 1 1 1 c

T3

X </) O.

.f—o , xa

u • *t- '— o <u o e

x: 3

4J <0 • • 4J

<0 4->

COU

cn c (o 0) e (0 c •r- e E 3 e

to o •r- +J <4- *o C O O

=0 tu ci:: (U T- (U «o <u x> (O o. e x:

i/) e 1/1 *4- +-* o> 4-> 4J w -o *•- e

01O (0 o la e Oi O 3 c c

CO 4-> 4->

O

ID

O

C

>> lo cn <u o u e <u E

f— o »- e •>“ o o O O 0) O 0) c in x: j= o.

*—1 4-> t/)

CT»

o>

Specimen

near

the

fracture.
w

Cl O

00

m

cr>

«

a.

2; n in

* * m ^ o

in CO r>.

c

o

•r- »»

10CTC m o

I— r— s tu a:

Io4JO

sz

D. CDC

^•r- R] • N ' •r-t. • 3 • Xi in

i- ^RHO O I

« '*».0 CDr- C

•r- X

N ( •I— r- ^ 4- . «- O*

r“3 U

ID 4-> •X fl) D) S. C

•r* C ' N f-

•r- (O O 1. f- <M X V) O

<0 f 4-> +J RJ C O •I- O •o o

0} m 4-J «?r ina 4-> •M R) o 4-» c

00 q; >» c

o

o >

c c

t—« a; o

in

CD

•r- U.

micrograph

of

the

fractured

specimen,

(b)

Scanning

electron

micrograph

at

the

region

of

fracture,

(c)

Photomicrograph

of

the

sectioned

specimen

near

the

fracture.
U)

to. Oo

UD

ta

Cl. 5l1 r“ I-* • • «J3 rs. o ^ CO VO

<ooc

(O o

>— r— cj; =} Lu o::

O)

t-3

4-> • • O c <u <o

0) Sk E 3 »4- t- ^ «- o o <u o <u <o o:

Q- S_ -4-) O) (/) H-

+J irtJ T3 *4- lO 1. a; o <u

1- c CSC •r- +> O C

lO

U *r- 04

C «0 O) EE +J 1- <U *r- 00 4- J_ u

04

«D 04 04 O. JZ JZ t/i O O lO o o04 O Q.

to VO V.o»

•M

O

lO 1.U

04 *r- = Eo C

•IO

x: o O04

00

00

04 ' •MO

CO VO

>» I o o r“ r— OO X

Q-+->

<oU

S. 04 O) OO oC 04 U f »r— 4-J c o o

s- .c M Q. U (O

04

C

I— cn

04 o

i. cn o c •!-E c o c +J

«o o U X c/0 OXI o

LO

cn

<o
rd

£

c

o

v»CL o

A CO

in

01c

N

*o

•r- «-

<0 c.

s: ^ »5 ^ id- 00 • • u3 cr> CTi CO CM ^

(OO)

c

CO o>“ O Ul Of

«/> oic

X

o

0) x:

+Jc

•a

0) +j

CO

0>

+-» o

oCO

>1o

600

®C

ata

strain

rate

of1

X

10“®/s.

(a)

Photomicrograph

of

the

fractured

specimen,

(b)

Scanning

electron

micrograph

at

the

region

of

fracture,

(c)

Photomicrograph

of

the

sectioned

specimen

near

the

fracture.
cnc

•r- Nl3 •

«/) i~ ^lOVO U 1 •p*to cn.—

o. c o

•rXN o •r- f

-D

•r- «*- r* »t- O

in r-“3 <U

fO

«/5 4-> ^ *o

Cl, cn

s: c

t- c

CO • • Nl tir> csj •r- fO CO CO VO •o 1. 1 1c 1

•r- +J X U> O

<o

OJ o x: 4->

+-> fO •M

R3 c o

O) •rO C

in o a o r~ C <u o

=3 LU c: +-> VO

to

<U -M M »0 O +J o c

CO <u ^ £

>> c o o O T- o > c c

•—I <u

cn

ID

cn

(a)

Photomicrograph

of

the

fractured

specimen,

(b)

Scanning

electron

micrograph

at

the

region

of

fracture,

(c)

Photomicrograph

of

the

sectioned

specimen

near

the

fracture.
450

®C

C_) o

O

lO

O

o

rO

<

(Th* O w

CM

(D lO ^ fO N

(Od^) *SS3dlS

Fig.

54.

Stress-strain

curves

for

Inconel

671

tested

at

450

®C

(840

®F)

and

600

(1100

®F)

in

He

and

in

oxidizing/sulfidizing

and

oxidizing/sulfidizing/

carburizinq

coal

Gasification

environments

at

a

strain

ratP

of1

x

in-o
Eo

lO

(/> o. o

<£> CO

cr>

«o

Ql. 2C ^CO o • • CO cvj r>.

«£> CO ro co4-> <dCD to o

h~ r—

=0 uj q: • a.

to la — i~ UJ cn 1 o c s- r— cn u c X •!- E

c:O 1— c +-> ra o

**-

u

X

O t/5 O-

<u ^M XI

u

«o '

s-c • • •r- C o;

IQ OJ 1- • s. E 3 OI +J -r- •M J_ to u O 3

OI <0 -4-> ro CL t- U

to »0 X> irtJ TO

CJ o o s- O) o 3 C X 4-> O o u •f— to <o cn tc; <0

t*-

u o

•M c

(0 (U

V

x:X c

O) 4-> •<-> O) 3: E

«t- •*-> *1- c o 10 tJ

•r— OJ ^ x: o. a Cl Q- (/) <u (O to 4J 1. S- "O

oo C7) cn oj

a; o o c

4-> S. t.

O

L>O

r- -I- T- +-> E E o

to o <u 4-> C to •— o o

<u x: s. <u c a. 4-> x: o u 4-> u —* 01 c «j •— **- •— — c; o
I/) CL oo

o>

le Q.

St. VS

lO CO o • • r». 00 to

VD ro ^co

<0o>c

(O o

H* ^ < Z3 ui cx:

O T3 o <u1. C 3

to 4->

"SJO

R) •P trtS

4-* O) c j:: <u 4-> iv- o o u

f- or > a. c <0

0)

u

o»

o> o c i. t- O N f-E

-a o

t- +-> H- O

r- x: 3 Cl. V)0> «3 C'-'

*0 to XV^ O Io<U I—

sz

4->

X

•a o

0)

4-> 0) to +J

<u <e •M 1. r- C

P>. VO 10w

f— 4J

0) v> co <e u

(O

VO

ir>

cn

specimen,

(bj

Scanning

electron

micrograph

at

the

region

of

fracture,

(c)

Photomicrograph

of

the

sectioned

specimen

near

the

fracture.
O)

s0)

+J

»*-

u o <o

s- c

o;Bco o

1. «4- *1- Oi

•I- o ct>j:z > 0) •*-> c sz u

O) a.

n) (U

s-<D cn (. x: (U C C7>4-> C

•rO

tM t. •«->

C

•'-0*0 01

1- •*- E 3 E x: •!- ^ UO O CL u

•f* &. <4-> IQ 0>

in «0

O L. CL

tx

U JC cn to o o cn i- -p o c ^ o o3 o •r- *0 ’r- C A N —' E O

r's •r* 'r- cn -o C <4-» 7” • o o 4- V) t. a<

<o I— ^+J to Ou 3VO U

2: Vi (/) 1 <U (U o n r- x: VO • • cnr- OI 4^ r- CO cn c

VO ro CO •IX 0>4- N CO

•1“ 4-

C Q. c X O <0 <o o o o &- X} •I— O) oo cn

<0o>c

(/) o

h~ r— <C

=> uj a:

01 -I-* o

x: *o-—' c

4J

C X) o c c E

•rO

(O • 4-> oa> u c o

4-> (U x:

4-> to E Dt/> 'r- W ro

r— «0 VO (_> oO c lo o ^uc 4-> •-I fo o ^<U U

CL'

in •a • o oi

i- i. 3 3 M -M U U

ra <e

to

cn
(a)

Photomicrograph

of

the

fractured

specimen,

(b)

Scanning

electron

micrograph

at

the

region

of

fracture,

(c)

Photomicrograph

of

the

sectioned

specimen

near

the

fracture.
<a c. to r>»

CTi o n i— CM

toO)c

to o

I- r- < =3 Ltl 0£

<_) -O

O

O Oi t.

t- 3 O 3 +J O -fJ U

to

U to • to i. OJ

4-> 1. **- t.

«0 *- 3

4- 4->

•4-> QJ

O

U c -c: lo

OJ 4->

C L. E ^ O ‘^- C H- -r- o o o> <u

i. 0) ^ ^ i- -M > o. C lO V 1.

<u fc. f <e cn+j (u cn o c c t_ <4-> •r- u »o C

rs4 f- <u -- E

-o

O Q.*t-

•*- -tJ « o

4- o S- Ql »— x: CD Cl 3 CL O </>

</>

uO "O

O)

m *r> 0) E Co N C f-

•r- • O

*0 (/) t.

U

f- 4-» <U XVO U «/l O I « O f— 0>

0) r— 0) x: x: .M

+J

X CDc **-

C o

•o o o

<«-> OJ too Id

4-> fe I— c

t- to <0

i.

4-^ <Uco <d uC -M H flO

Id CL a <d to w

CD ^ o

X2

Wu

•r*E • o C 4-» (U O E x:

«r- O- U

(U

—

CL

O

to :
'V E

u

«/> CL O

cn

#> iO

<o a. ^CO 00

00 • • ^ iO ^ r— I

c

o

(O

CT> c

U) o

I— r- C =3 LU o:

Fig.

60.

Inconel

671

tested

in

the

oxidizinq/sulfidizing/carburizing

environment

at

600

®C

ata

strain

rate

of1

X

T0“O/s.

(a)

Photomicrograph

of

the

fractured

specimen,

(b)

Scanning

electron

micrograph

at

the

region

of

fracture,

(c)

Photomicrograph

of

the

sectioned

specimen

near

the

fracture.
Fig. 61. Inconel 671 tested at 600 ®C in oxid izing/sulfidizing/carburizing

environment at 1 X 10‘6/s. (Top to Bottom) Alpha-chromium phase

present in alloy due to combined effects of temperature and strain.

Progressing from maximum strain (fracture surface) to a smaller

strain (near shoulder area of reduced section). 200 X.
NBS*1I4A IF4CV. s-Tai

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBSIR 81-2191 (DoE)2.Cuv't. Accession No. 3. Recipient' j Acctssien No.

4. TITLE AND SUBTITLE

The Use of the Slow Strain Rate Technique for the Evaluation

of Structural Materials for Application in High-temperature

Caseous Environments

S. Publication D.itc

6 . Performing Organisation Code

561

7. AUTHOR(S)

G. M. Ugiansky and C. E. Johnson

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, DC 20234

10. Project/Task/Work Unit No.

11. Contract/Grant No.

12. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS fSrreer, City, State, ZIP)

Department of Energy

Division of Systems Engineering/Energy Technology

Mail Stop GTN C-155

Washington, DC 20545

13. Type of Report & Period Covered

Final

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

I

I Document describes a computer program; SF-185, FIPS Sof^vare Summary, is attached.

16. ABSTRACT (A 200-word or less tactual summary ot most signiticant information. It document includes a significant bibliography or

literature survey, mention it here.) The slow Strain rate technique has been evaluated as an accelerated test for

determining the performance of structural materials in simulated coal gasification

environments. Seven alloys, namely Types 309, 3l0, 3lOS, 347 and 446 stainless

steels; Incoloy 800; and Inconel 671, were tested at temperatures from 370 C to

1040 °C at strain rates from 10““^ to l07^/s in HgS plus water, gaseous mixtures of

CO, CO2 , H2 , CH^, H2 S, and H2O, and in nominally inert environments of He and Ar.

Type 310 steel, the most extensively studied material, showed a marked reduction in

mechanical properties at low strain rates (<lO”®/s) in H

2 S/H2 O at 540 C, and this

was associated with the occurrence of a large degree of secondary intergranular crack

ing in addition to the main ductile fracture mode. The occurrence of the secondary

cracking was taken as the primary indication of embrittlement in subsequent tests.

Of particular significance, it occurred to some degree in all alloys tested in the

simulated coal-gasification environments at 600 C. Consequently, the mechanism(s) of

the embrittlement phenomena remain uncertain; a number of possible causes including

creep and several environmentally-induced fracture processes are outlined. It is

shown that the overall results of the test program are in good agreement with in-plan

experience. It is concluded that the slow strain rate technique is an effective

method for evaluating the performance of structural materials in the elevatedtemperature gaseous environments.

17* KEY WORDS (six to twelve entries; aiphabeticei order; capitatixe only the (irat letter o( the (irat key word unleee m proper name;

eeparated by aemicolor\s)

Austenitic stainless steels; coal gasification; elevated temperatures; ferritic

stainless steel; gaseous environments; nickel alloy 671; nickel alloy 800; slow

strain rate test; structural materials

U. AVAILABILITY [X] Unlimited

I For Official Distribution. Do Not Release to NTIS

r~] Order From Sup. of Doc., U.S. Government Printing Office, Washington, DC

20402, SD Stock No. SN003-003-

f~1 Order From National Technical Information Service (NTIS), Springfield,

VA. 22161

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

21. NO. OF

PRINTED PAGES

20w SECURITY CLASS 22. Price (THIS PAGE)

UNCLASSIFIED

USCOMM-OC
[I
4