NATL INST OF STAND S TECH

A111D7 3TDbOD

NBS

PUBLICATIONS

NBSIR 84-2839

Mechanical Properties of A Leaded,

Resulfurized, Rephosphorized Steel

in Various Thermo/Mechanical

Conditions

U.S. DEPARTMENT OP COMMERCE

National Bureau of Standards

National Measurement Laboratory

Metallurgy Division

Washington, DC 20234

January 1 984

Final Report

issued March 1 984

Drepared for «« "sited States Coast Guard

apartment of Transportation

1 ashington, DC 20590

.1156

34-2339

1934

NATIONAL BUREAU OF STANDARDS

LIBRARY

NBSIR 84-2839

MECHANICAL PROPERTIES OF A LEADED,

RESULFURIZED, REPHOSPHORIZED STEEL

IN VARIOUS THERMO/MECHANICAL

CONDITIONS

J. G. Early

U S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Measurement Laboratory

Metallurgy Division

Washington, DC 20234

January 1 984

Final Report

Issued March 1 984

Prepared for United States Coast Guard

Department of Transportation

Washington, DC 20590

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

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

Q*

INTRODUCTION

The National Bureau of Standards (NBS) was requested by the U.S.

Coast Guard, Department of Transportation to conduct a limited metallurgical evaluation of samples of a leaded, re-sul furi zed, re-phosphori zed

f reemachi ni ng steel. This class of steel is often used for applications

in which substantial metal is removed by machining operations. Subsequent

joining operations, such as brazing, are also often specified.

Machi nabi 1 i ty is strongly influenced by such mechanical properties

as strength, hardness, and ductility. [1 ,2]* In carbon steels, tnese

properties are controlled primarily by the carbon content. Annealed

low carbon steels (less than 0.15% C) often do not have good macnining

characteristics because of poor chip forming behavior due to low strength.

Improved machi nabi 1 i ty can be achieved through additional processing

operations such as heat treating or cold working. Higher carbon steels

(greater than 0.35% C) exhibit satisfactory chip characteri sti cs , but

cause greater cutting tool wear as a result of substantially higher

hardness. If cutting speed is reduced to improve tool wear, then surface

quality often decreases. To iiTprove the machi nabi 1 ity of the higher

carbon pearlitic steels, heat treating to partially spheroidize the

mi crost ructure is necessary.

An alternative approach to these additional costly processing steps

is to select a modified chemical composition to enhance machi nabi 1 i ty

while maintaining the desired mechanical properties. Higher concentrations of sulfur (re-sul furi zed steels), phosphorous (re-phosphori zed

steels), and lead (leaded steels), whether added individually or in

combination, enhance steel machi nabi 1 i ty . These additions result in

increased machining speed or improved surface finish through their

influence on chip formation and cutting tool lubrication. The effect of

increased sulfur content (up to 0.35%) is primarily through control of

the shape, size, and distribution of manganese sulfide inclusions. These

inclusions favor broken rather than continuous chips and act as a lubricant

to prevent chip adherence on the tool. Increased phosphorous levels (up

to 0.12%) strengthens the steel (ferrite strengthener) and aids chip

break-up. Upper limits for phosphorus additions are required, however,

since increased hardness and strength eventually lowers machi nabi 1 i ty and

leads to excessive of tool wear. Lead, although essentially insoluble in

both liquid and solid steel, can be added without gross segregation in

amounts up to 0.35% as a result of modern steel making practice. The

lead, usually founa as a fine dispersion associated with the manganese

sulfide inclusions, acts in a similar manner to sulfur but does not

degrade room temperature mechanical properties.

The purpose of this metallurgical evaluation was to determine the

mechanical properties of one grade of free-machining steel in bar *orm in

several thermo/ mechanical conditions and to correlate the measured

*Numbers in brackets refer to references listed at the end of the report.
mechanical properties with its microstructure. The effect of subsequent

thermal processing, e.g. brazing, on mechanical properties was also

i nvesti gated.

MATERIAL

The material selected for this study was reportedly produced to

American Iron and Steel Institute ( A I S I ) grade 12L14. The nominal

specified composition for this grade is: carbon 0.15% max; manganese

0.85-1.15%, sulfur 0 . 26%-0. 35% ; phosphorus 0.04-0.09%; and lead 0.15-

0.35%. [3, 4] The as-received samples were in the form of eight foot

(2.44 m) lengths of bar stock cut from longer lengths. The bar stock

samples were supplied in the following sizes and reported thermo/mechanical conditions: 3/4 inch (19 mm) diameter, cold finished hexagonal

bars; 3/4-inch (19mm) diameter, hot rolled round bars; 1-1/2 inch

(38 mm) diameter, cold finished hexagonal bars; and 1-1/2 inch (38 mm)

diameter, hot rolled round bars.

Flat rolled steel products are classified as either hot rolled or cold finished. [5] Hot rolled products are produced entirely at elevated

temperatures with the final thickness or diameter of carbon steels

achieved at temperatures above the lower transformati on temperature.

Cold rolled products are actually only cold finished because most of

the size reduction operations are carried out hot as for hot rolled

products. Generally, cold finished products receive enough cold working

in the final rolling operations to improve the surface finish and

affect the mechanical properties of the final product.

In order to investigate the role of a subsequent thermal processing

operation, portions of one length of 1-1/2 inch (38 mm) cold finished

bar stock were subjected to the thermal cycle of a commercial brazing

process. In this report, these samples will be referred to as being in

the cold finished/heat treated condition. Individual pieces of bar

stock (without the brazing alloy) were placed along side actual components

passing through a continuous brazing furnace. [6]

The brazing furnace was a four zone furnace, 42 feet (13 m) long.

The conveyor belt moved at a speed of six inches/minute (15 cm/minute).

A slightly reducing atmosphere was maintained throughout the furnace,

although only the second zone 4 feet (1.2 m) long and the third zone 2 feet (0.6 m) long were directly heated. The zones were not separated

so heating also occurred throughout zone 1. The second zone was controlled

at 2100 F (1149 C) and the combination of zone length, belt speed, and

temperature caused the metal parts to reach this temperature at the end

of zone 2 without a significant soaking period. The third zone was set

at a lower temperature so that slow cooling occurred before entering

the unheated fourth zone where the parts cooled to about 150 F (66 C).

The entire cycle took approximately 1 hour 24 minutes to complete.

2
EXPERIMENTAL PROCEDURE

Tensile properties and standard Charpy V-notch impact properties

were determined, hardness surveys performed, and microscopic observations

made on each bar stock size in each thermo/mechanical condition.

Longitudinal specimens (specimen axis aligned parallel to bar axis)

were prepared for the tensile tests and Charpy inpact tests.

Metal! ographi c Analysis and Hardness Survey

Representative photomi crographs were obtained from selected polished

and etched areas oriented parallel and perpendi cul ar to the bar axis

of each type of bar stock. The ferrite grain size was measured in

accordance with the circular intercept method from ASTM El 12-74, Intercept

Method.

Rockwell B hardness measurements were made on specimens adjacent

to the metallographic specimens and correlated with the mi crostructure

of each bar sample. Hardness measurements were obtained on transverse

sections, from surface-to-surface across the bar diameter.

Mechanical Property Testing

Longitudinal test specimens for both tensile tests and Charpy impact

tests were taken as closely as possible from the quarter diameter positions

in each type of bar stock. A schematic of the tests specimen orientation

and location followed in this study is shown in Figure 1. A broach was

used to create a uniform and reproducible V-notch in the Charpy specimens,

and the notch was oriented (in the specimen) approximately facing the

center of the bar. The tensile specimens, standard 0.250 inch (6.3 mm)

in diameter with a 1-inch (25.4 mm) gage length, and standard 0.394

inch (10 mm) Charpy V-notch specimens were tested, respectfully, in

accordance with ASTM A370-73, Mechanical Testing of Steel Products, and

ASTM E23-72, Notched Bar Impact Testing of Metallic Materials.

RESULTS AND DISCUSSION

Metallographic Analyses and Hardness Measurements

Representative photomi crographs taken at low magnification on longitudinal and transverse planes of unetched samples of the as-received

bars are shown in Figure 2. Numerous thick and thin inclusions, primari ly

manganese sulfide, can be seen, and this observation is consistent with

the higher permitted sulfur content for this steel. Tne fine lead

droplets are not observed at this magnification. This inclusion microstructure is contrasted with that found in a steel of similar manganese

content (1.15%) but a much lower sulfur content (0.017%), Figure 3. In the low sulfur steel, the manganese sulfide inclusion are all thin and

the inclusion volume fraction is lower than for the high sulfur steel

used in this study.
Representative microstructures of each as-received sample are shown

in the etched condition in Figure 4. The mi crostructure of the sample

of the 1-1/2 inch (38 mm) bar in the cold finished/heat treated condition

is shown in Figure 5. The mi crostructures are typical of low-carbon

steels and consist primarily of proeutectoid ferrite with small amounts

of pearl ite. The longitudinal photomicrographs of both the hot rolled

and the cold finished bars show the ferrite grains to be equiaxed and

the pearl ite and inclusions aligned parallel to the bar axis. The

pearlite distribution anisotrophy (often called banding in plate

products) is a result of chemical segregation in the original ingot

which has now been elongated parallel to the bar axis as a result of

the bar forming operations.

The measured ferrite grain sizes are reported in Table I. Ferrite

grain sizes is strongly influenced by the prior austenite grain size, the

cooling rate through the transformation temperature, and any subsequent

thermo/mechanical processing after the initial austeni te-to-ferri te/pearlite transformation. The absence of any evidence of elongated ferrite

grains in either of the sizes of hexagonal bars suggests that the cold

worked bars were re-heated or stress relieved just before or after the

final forming operation so that the ferrite grains recrystal 1 i zed.

Stress relieving of cold finished bars is often done to change the size

and distribution of residual stresses.

The observations that both of the small diameter bars, 3/4 inch

(19 mm) hexagonal and round, had almost the same ferrite grain size,

and both of the larger diameter bars 1-1/2 inch (38 mm) hexagonal and

round, had the identical but somewhat larger ferrite grain size, indicated

that the hot finishing temperatures for both sizes of both hexagonal

and round bars were probably similar. The somewhat larger grain size

in the larger diameter bars probably resulted from a slower cooling

rate through the transformation temperature due to their larger mass. The grain size for the cold finished/heat treated 1-1/2 inch (38 mm)

bar condition was the same as the other 1-1/2 inch (38 mm) bars suggesting

that the brazing cycle heat treatment did not cause any change in

mi crostructure.

The results of the hardness measurements are shown in Table II.

The average Rockwell B hardness values for the cold finished bars was twenty-two hardness points higher for each size than for the hot rolled

bars HRB 86 vs. 64 for the smaller diameter bars, HRB 81-1/2 vs. 60 for

the larger diameter bars. The average hardness value for the 1-1/2

inch (38 mm) bar samples in the cold finished/heat treated condition,

HRB 61-1/2, is similar to the values for the hot rolled bars, HRB 64

and 60, and considerably lower than the values for the cold finished

bars, HRB 86 and 81-1/2. This indicates that the brazing cycle heat

treatment was similar in effect to a process anneal or stress relief

heat treatment.

The hardness profiles for the two sizes of cold finished bars are quite uniform except for the values measured nearest the bar surfaces

4
which are slightly higher, possibly due to a final cold forming operation

that work hardened the surface slightly. The hardness profiles for the

two sizes of hot rolled bars were also very uniform except for the

values nearest the bar surface in the smaller bar which are slightly

lower. This may have resulted from some decarburi zati on of the surface.

Tensile Properties

The measured tensile properties of each bar size and condition are given in Table III. The average ultimate tensile strength and yield

strength values for the 3/4 inch (19 mm) bars, in both the cold finished

and hot rolled conditions, were somewhat higher than for the 1-1/2 inch

(38mm) bars finished to the same conditions. These differences, which

appear to be a function of bar diameter, are consistent with the grain

size measurements and the hardness profile measurements. The smaller

diameter bars, in each thermo/mechanical condition, had a finer ferrite

grain size (resulting in higher yield strength) and higher average

hardness values (resulting in higher ultimate tensile strength) than

the larger diameter bars.

The average ultimate tensile strength and yield strength values

for the bars tested in the cold finished condition were substantially

higher than for the bars tested in the hot rolled condition. The

average ultimate-tensile strength values for the cold finished condition

and the hot rolled condition for the 3/4" inch (19 mm) bars were 75.8

Ksi (522 MPa) and 58.8 Ksi (405 MPa), respectively, while the average

0.2% offset yield-strength values were 71.0 Ksi (489 MPa) and 43.0 Ksi

(296 MPa), respectively. For the 1-1/2 inch (38 mm) bars, the average

ultimate tensile strength values in the cold finished condition and the

hot rolled condition were 73.9 Ksi (510 MPa) and 54.3 Ksi (374 MPa),

respectively, while the average 0.2% offset yi el d-strength values were

68.6 Ksi (473 MPa) and 35.8 Ksi (247 MPa), respecti vely . For samples

of the 1-1/2 inch (38 mm) bar in the cold finished/heat treated condition,

the average ultimate tensile strength and 0.2% offset yield-strength

values of 54.9 Ksi (378 MPa) and 32.9 ksi (226 MPa), respecti vely , are very close to the values (54.3 Ksi and 35.8 Ksi), for the 1-1/2 inch

(38 mm) hot finished bar.

The ultimate-tensile-strength data can be compared with the hardness

measurements. Using a reported [7] empirical relationship between

hardness and ultimate tensile strength, the measured average hardness

values of HRB 86 and HRB 81.3, respecti vely , for the 3/4 inch (19 mm)

and the 1-1/2 inch (38 mm) cold finished bars correspond to ultimatetensile strength values of 81 Ksi (558 MPa) and 75 Ksi (517 MPa),

reespecti vely . The measured average ultimate-tensile-strength values

of 75.8 Ksi (522 MPa) and 73.9 Ksi (510 MPa), respectively, are 6% and

1-1/2% lower than the predicted values. The measured average hardness

value of HRB 64 for the 3/4 inch (19 mm) hot rolled bar corresponds to

an ultimate-tensile-strength value of 56 Ksi (386 MPa). The measured

average ultimate-tensile-strength value of 58.8 Ksi (405 MPa) is 5%

above the predicted value. The measured average hardness value of HRB

5
60 and HRB 61.5, respectively, for the 1-1/2 inch (38 mm) hot rolled

bar and the 1-1/2 inch (38 mm) cold finished/heat treated bar fall

below the lowest value (HRB 64, 56 Ksi) reported for the empirical

hardness-tensile strength relationship and thus the equivalent ultimate

tensile strength values would be below 56 Ksi. The measured ultimatetensile-strength values of 54.3 Ksi (374 MPa) and 54.9 Ksi (378 MPa) are consistent with the predicted values of less than 56 Ksi (386 MPa).

This generally good agreement between the empirically derived ultimatetensile-strength values and the measured values (within + 6%) is as good as can be expected for this type of correlation and confirms the

expected trends between hardness and ultimate tensile strength.

The yielding behavior can provide further evidence as to the

effect of cold work on mechanical properties. Sufficient cold work can lead to the elimination of a sharp yield point, increases in ultimate

tensile strength and yield strength, decreases in ductility, and increases

in the ducti le-to-brittle transition temperature as measured by Charpy

V-notch impact tests. Schematics of the typical stress-strai n curves observed are shown in Figure 6. None of the specimens taken from

either diameter of the cold finished bars exhibited a sharp yield

point. All of the specimens from both diameters of the hot rolled bar

exhibited sharp yield points with measurable upper and lower yield

point values. The specimens from the cold finished/heat treated

bar also exhibited upper and lower yield points.

The absence of sharp yield points in the cold finished specimens

indicates that the cold work introduced by the final cold forming

operation was sufficient to eliminate the yield point observed in the

hot rolled condition and to increase substantially the yield strength.

The re-appearance of a sharp yield point in the cold finished bar

subjected to the brazing thermal treatment indicates that the thermal

treatment was sufficient to remove the effects of cold work.

Calculated values of the yield strength/tensile strength ratio, ay/au

for the cold finished bars (0.94 and 0.93) illustrate the strong influence

of the cold finishing process on increasing the yield strength when

compared to the ratio for the hot rolled bars (0.73 and 0.66). The

high (yield/tensile) ratio for the cold finished bars demonstrates the

low capacity for work hardening in this condition. The bars in the hot

rolled condition, however, can be work hardened considerably more. The

average yield/tensile ratio (0.60) for the cold finished/heat treated

samples is very close to the hot rolled values and indicates a complete

recovery from the strengthening due to the cold finishing operations.

The average tensile ductility values as measured by percent elongation

and percent reduction-in area for the 3/4 inch (19 mm) bars, in both the

cold finished and the hot rolled conditions, were generally lower than

for the 1-1/2 inch (38 mm) bars in the same conditions. These tensile

ductility results (compared to the data for the larger diameter bars) are in agreement with the somewhat higher strength, higher hardness, and

finer grain size reported for the smaller diameter bars.

6
The average tensile ductility values for both bar sizes in the cold

finished condition were substantially lower than for both sizes in the

hot rolled condition, e.g. percent elongation values for the cold

finished samples were less than one-half that for the hot rolled samples.

The average percent elongation and percent reducti on-i n-area values for

the cold finished/heat treated samples of the 1-1/2 inch (38 mm) bar

(38.3% and 64%, respectively) were very close to the values for the hot

rolled bar (39.7% and 65%, respecti vely ) . This further confirms the

recovery from the effects of cold finishing.

Impact Properties

The notched impact toughness properties as measured by the Charpy

V-notch (CVN) impact test for each bar size and thermo/mechanical condition

are given in Tables IV, V, and VI and Figures 7 and 8 for two widely used

fracture criteria: energy absorption and shear fracture appearance (SFA).

Carbon steels generally exhibit a well-defined ducti 1 e-to-bri ttl

temperature transition as measured by the temperature dependence of the

fracture criteria. Brittle or cleavage fracture is observed at temperatures below the lower knee of the curves (Figures 7 and 8); ductile or shear fracture is observed at temperatures above the upper knee of the

curves; and a mixture of ductile and brittle fracture modes are found

in the temperature region between the two knees. The temperature

transition regions for the cold finished bars and hot rolled bars are different regardless of bar diameter; further, for each thermo/mechanical

condition, the temperature transition regions for the 3/4 inch (19 mm)

bars are different than those of the 1-1/2 inch (38 mm) bars. These

conclusions are illustrated in the SFA plot. The CVN transition region

for the 3/4 inch (19 mm) and 1-1/2 inch (38 mm) cold finished bars

extends from 0 F (-18 C) to +120 F (+49 C) and from OF (-18 C) to +180

F (+82 C), respecti vely . The CVN transition region for the hot rolled

bars extends from <-60 F (<-51 C) to +40 F (+4 C) and from <-60 F (<-51

C) to +100 F (+38 C), respecti vely . The CVN transition range for the

cold finished/heat treated bar extends from -40 F (-40 C) to +120 F (+49 C). The Charpy V-notch ducti 1 e-to-bri ttl e transition temperature

of carbon steels, often characteri zed by the 15 ft-lb (20 joules)

transition temperature or the 50 percent SFA transition temperature, is

primarily controlled by the steel chemistry, (decreasing transition

temperature with increasing manganese/carbon ratio), ferrite grain size

(decreasing transition temperature with decreasing grain size), and the

thermo/mechanical condition (increasing transition temperature with increasing cold work). In the present study, the steel chemistry is assumed

to be similar for all samples. As shown in Figures 7 and 8, the thermo/

mechanical condition has the major influence on the transition temperature.

Both sizes of cold finished bars exhibit higher transition temperatures

(lower toughness) than the hot rolled bars as a result of the effect of

the cold work. The transition temperatures of the bars in the cold

finished/heat treated condition falls in between the cold finished and

hot rolled values. Further, for both toughness criteria, the smaller

diameter bars in either the cold finished or the hot rolled condition

7
exhibit lower transition temperatures (higher toughness) than the

larger diameter bars. This observation is consistent with the effect

of increasing toughness with decreasing ferrite grain size.

The upper shelf energy absorption values for the 1-1/2 inch (38 mm)

bars in both the cold finished and the hot rolled conditions (38 ft -lbs,

52 joules and 70 ft-lbs, 95 joules) are higher than the values measured

for the 3/4 inch (19 mm) bars in the same conditions. Further, the

upper shelf energy absorption values for the hot rolled bars (58 ft-lbs,

79 joules and 70 ft-lbs, 95 joules) are substantially higher than for

the cold finished bars (31 ft-lbs, 42 joules and 38 ft-lbs, 52 joules).

These observations are in agreement with the hardness data discussed

earlier in this report where it was found that the hardness of the cold

finished bars was substantially higher than for the hot rolled bars,

and, for each thermo/mechani cal condition, the smaller diameter bars

exhibited higher hardness than the larger diameter bars. In addition,

there is a direct relationship between the upper shelf energy absorption

values and the measured yield strength; as the yield strength values

increase, the energy absorption values decrease. This observation is

in good agreement with studies reported for a wide variety of steels in

various heat treated conditions, including carbon/ manganese steels. [8]

Visual inspection of the tested Charpy specimens revealed a change

in fracture behavior in some hot rolled bar specimens tested at temperatures on the upper shelf plateau. As shown in Table IV, the upper shelf

energy absorption plateau (67 to 72 ft-lbs, 91 to 98 joules) was reached

in the temperature range of 72 F (22 C) to 123 F (31 C) for the 1-1/2

inch (38 mm) hot rolled bar. Similarly, 100 per cent SFA was attained

over this same temperature range. A specimen tested at 164 F (73 C),

however, did not fracture and exhibited an abnormally high energy

absorption compared to the upper shelf plateau. Examination of the

specimen (Figure 9a) revealed that a tensile stress overload bent the

specimen with little or no evidence of crack propagation from the

bottom of the V-notch. Further, the specimen exhibited splitting

perpendi cul ar to the V-notch and parallel to the long axis, in the

principal bar deformation direction. This behavior indicated that a change in fracture mode occurred over the temperature range between 123

F (51 C) and 164 F (73 C).

The identical behavior was observed in specimens from the 3/4 inch

(19 mm) hot rolled bar. The upper shelf energy absorption plateau (55

to 60 ft-lbs, 75 to 82 joules) and the 100 percent SFA were reached in

the temperature range of OF (18 C) to 32 F (0 C). Specimens tested

above 55 F (13 C) did not fracture and exhibited abnormally large

energy absorption values. Examination of these specimens (Figure 9b)

revealed the same features as observed in the 1-1/2 inch (38 mm) specimen.

One specimen from the 1-1/2 inch (38 mm) cold finished/heat treated bar

also behaved in a similar manner. In this thermo/mechanical condition,

however, greater variability in fracture behavior was found. Although

two specimens were tested at 123 F (51 C), one specimen at 163 F (73

C), and one specimen at 209 F (98 C), only one of the specimens tested

at 123 F (51 C) exhibited bending failure and splitting.

8
The energy absorption data from specimens exhibiting bending failure

have no significance because the high energy absorption results from the

bending of the test specimen, its ejection from the holding fixture, and

the friction forces overcome as the specimen was pushed out of the Charpy

test machine. These data are not shown in Figures 7 and 8. None of the

specimens from the cold finished bars exhibited this behavior over the

range of test temperatures

SUMMARY

The results of the metallurgical evaluation of bar stock samples

of AISI 12214 steel in two thermo/mechanical conditions, cold finished

and hot rolled, illustrate the dominant role that the thermo/mechanical

condition has on the resulting mechanical properties. The contributing

effects of ferrite grain size and bar diameter on mechanical properties

were small in comparison to the effects of cold work during the cold

finishing operation. Cold finished bar stock samples subjected to a thermal brazing cycle (without the brazing alloy) develop mechanical

properties that are very similar to those attained in hot rolled bars.

ACKNOWLDGEMENT

The author wishes to thank Mr. C. H. Brady for his contributions to

the metal 1 ographi c and grain size determination portions of this report.

Special thanks to Mrs. Mary Wykes for her assistance in preparing the

final version of this report.

9
REFERENCES

1. Metals Handbook, Vol. 1, Properties and Selection of Metals, 8th Edition,

American Society for Metals, 1961, pp. 304-309.

2. Metals Handbook, Vol. 1, Properties and Selection: Irons and Steels,

9th Edition, American Society for Metals, 1978, pp. 572-578.

3. American Society for Testing and Materials Specification A1 08-81

,

"Standard Specification for Steel Bars, Carbon, Cold-Finished, Special

Quality."

4. American Society for Testing and Materials Specification A576-81 , "Standard Specification for Steel Bars, Carbon, Hot -Wrought, Special

Quality."

5. The Making, Shaping and Treating of Steel, U.S. Steel Corporation,

1971, pp. 932-93.

6. Private Communication, W. Currie, Parker-Hanni f i n Corp., January 4, 1984.

7. Army-Navy Approximate Hardness Tensile Strength Relationship of

Carbon and Low Alloy Steels, AN-QQ-H - 201 , 1943.

.8. Gross, J. H., "The Effective Utilization of Yield Strength," J. Engr.

Industry, ASME Paper No. 71-PVP-ll, 1971.

10
Table I. Ferrite Grain Size Measurements

Ferrite Grain

Condition Diameter Size( a )

Cold Finished 3/4 inch (19 mm) 8

Cold Finished 1-1/2 inch (38 mm) 7

Hot Rolled 3/4 inch (19 mm) 8-1/2

HoT Rolled 1-1/2 inch (38 mm) 7 Cold Finished 1-1/2 inch (38 mm) 7 and Heat Treated

(^Measured according to ASTM El 12—74, Intercept Method

Table II. Hardness Profile Measurements

Condition

Cold Fi ni shed

Cold Finished

Hot Rolled

Hot Rolled

Rockwell "B" Scale

Bar Average

Diameter Hardness Values Hardness

3/4 inch (19 mm) 87,85-1/2,85-1 /2,85,85,85,88 86

1-1/2 inch (38 mm) 84,81 ,79,80,80,82,83 81 .3

3/4 inch (19 mm) 61 -1/2,65,66,67,65-1/2,63-1/2,61 64

1-1/1 inch (38 mm) 61,59,58,58-1/2,58,58,60 60

Cold Fi ni shed 1-1/2 i nch (38 mm)

and Heat Treated

61 ,61-1/2,62,62 61.5

Table

III.

Tensile

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CD Z

4-> +J

03 03 E c

•r- a> 03 co 03

O 03 03 CO CO CM CO r-H LO

4-> <- •- 1— -P cn LO LO LO O' CO CO CO CO CO ^p ^P *^p LO rj" D IP y p^ p^ LO LO LO LO LO LO LO LO

<D 0) • 03 03 <3 3 a 0 r— >T3 03 O r— 03 03

CL) • r—

r— CM CO t_ r-H r— <0 r— CM rO r-H ^P

CLO 1

i— ai 1— 1— O) £_ 1— )— C_ t— l—

00 2: 0 0 > O CJ > 1— i— 3 z Z 3 0 CJ

fO CO z z > >

<T3 03 E E E TO

** E r*

E cz 3 E F 4-J E co c= co 00 T3 0 CO -0 CO CO TD 3

03 aj cu 03 >— aj L_ |— z J3

r— r~ hcn Z CO >—" 0 _£Z a SZ LO c •r— U aj u 3 u 4-> T3 O JC c c c Z r— c ( c c fT3 C -t- CJ •r— •f— »r— <j r— • r- r— •r— *r— 3

n3 4-> <z u_ Ll_ c 0 0 U- ~r~ •r— •1— CM •r— cc CM QC CXJ 3 "O TO "O TO M C r— r-H r— ^P *-> r—H 4-> r-H c:

•I—

O \ 0 1 0 0 I 0 t 0 ^3 CO cj PO 0 t—

C_3 CO z r-H z •-H CJ o

*=s- LO

co• coon

co

C\J CM

CO

co

C\J r»

C\J

LO• 03POoCO

CO

CM

CM

03• C\J co

00

CO

<T>

LO

O)C7) <T3 t->

Table

IV.

Energy

Absorption

Data

Summary 3o

-O

</) <U E T3 r— e =

re oo

co ~o —' QJ "O

-c aj JX l/l .(_> U -r- (T3 C C a) i- c_ U_ I— 00 JO a +j r— >— re i o aj -•-> UX H-

</) ai

CVJ

COCO 3o

"O

JO -o

OJ 0) tx I

o VI

CVJ QC .Q o -*-> •—' l/l E CL) E <—3

ai o

r— re ' "O

aj jx 

OJ r— C O V) V- OC JO

re- +j i O +j co zn 4- E vi E aj CO 3

co -a o —- <u JO -3 00 a •<- c c

•r— *i— U_ 1/1 CVJ X) ^-"O 1—

r-i i I i O -t-> 1—10 4— E VI E U

-O I—

Cl HI 3 i— X O

OO '“0

OJ -r- C Ll_ CO

•i- JO

-O r—

re- 1— i \ o +j CO C_5 4-

ajCO 3

+J 4-> re OO t_ a; aj I— Q.Ll_ E

OJ

COI on

CO

Ol OO

CVJ

CVJ

CVJ

CVI rHi

CO

CVJ

CVJ

LOI oOOI

CVJ o

rei orei o

rei

co

on

CVJi CVJ re01

CVJ o

CVJI

ai

CVJi OO

OO

CVI

CO

CVII CTv on

CVJ

on

cvji CO

co

CVJI Ol

I-'.

CVJ

CO

CVI

CO

CVJI CVI

co

CVJ

CVI

CVJI CO

CVJ

CVJ

OO r— 1— CVJ

on

re COre

co

CO

reCO

on

r--

onm

cvji on

cvji CO

Ol

CO I OO

CVI co

CVJ CO

COre

CVJ

CO

CVJI Ol

COI Ol

on

on

CVI

CVJI on

on

on

CVIi COI

re- on

CO

CVJI Ol

on

CVJI o

CO

CVJ

CVJ

CVJ

cvj r--

oi

oo

OlOl

ono

CVJ

CVJ Ol

on

Ol

co

r-.I CVI Ol

COOl

00

OO

CVJI re

r*.

r-^ oo co

oo

CVJ

CVI onCVI I CO

re- 00

on o

on

CVJ

co

co

cvji re

cvj

CVJ CVJ

CVJ

r*. i oo CO on

co

CVJ co

cvj re

r^. co

CVI

COCOooco

cooo oCO

CO

cvj CO

CVI re re OO O — CVJ

Table

V.

Shear

Fracture

Appearance

Data

Summary

Table VI. Summary of Transition Temperature and Upper Shelf Behavior

Size and

Condition

Upper Shelf

Energy Absorption

ft-lbs Joules

Energy Absorption

Transition Temperature

F C

Shear Fracture Appearance

Transition Temperature

F C

3/4 i nch (19 mm)

Cold Finished

31 42 +63 +17 +72 +22

1 -1 /2 i nch (38 mm)

Cold Finished

38 52 +93 +34 +102 +39

3/4 i nch (19 mm)

Hot Rol 1 ed

58 79 -32 -36 -22 -30

1 -1 /2 i nch (38 mm)

Hot Rolled

70 95 +6 -14 +32 0

1 -1 /2 i nch (38 mm)

Cold Finished and

Heat Treated

75 102 +27 -3 +62 +17

a.

b.

Fiaure 1. Schematic of Test Specimen Location and Orientation

a. Tensile Test Specimens

b. Charpy V-notch Impact Specimens

b.

Figure 2. Representative Photomicrographs of Inclusion Pattern

a. 3/4 inch (19 mm) hexagonal bar, cold finished

b. 1-1/2 inch (38 mm) hexagonal bar, cold finished

Longitudinal Plane Unetched Magnification: X100

c

Figure 2. (Cont)

c. 3/4 inch (19 mm) round bar, hot rolled

d. 1-1/2 inch (38 mm) round bar, hot rolled

Longitudinal Plane Unetched Magnification: X100

Figure 3. Representative Photomicrograph of a Low Sulfur Steel (0.017% S)

Longitudinal Plane Unetched Magnification: XI 00

cr

Q<

r igure 4. Photomicrographs o^ .ypical itcnec crest ructures

. 3/4 inch (19 mm) hexagonal oar, colt ^'nisned

. 1-1/2 inch (38 fm) hexagonal bar, cold fini

Longitudinal ?! ane Etch: 2\ Nital **agni cation:

C) O

d.

Figure 4. (Coni:)

. 3/4 inch (19 nun) round oar, nor rolled

. 1-1/2 inch (33 mm) round bar, rot •'oi’ec

Longitudinal P lane Eton: 2\ Cital ''acn-i f 'cat'c r

:

Figure 5. Typical Microstructure of Cold Finished/Heat Treated Ba

1-1/2 inch (38 mm) hexagonal Bar

Longitudinal Plane Etch: 2% Nital Magnification: X100

STRAIN

Figure 5 .

MPa

Schematic of Observed Engineering Stress-Strain Curves

a. Cold Finished Condition

b. Hot Rolled Condition; and Cold Finished/Heat Treated Condition

AISI

12L14

STEEL

3/4

inch

CI9

mm),

Cold

Finished

JOULES

can-ij> a39dosav asj3N3

Absorption

Temperature

Transition

Cur

AISI

1

2L

1

4

STEEL

1/2

inch

C38

mm),

Cold

Finished

JOULES


 Q LO Q LO

LO (\1 © Q

COr-COLO^OOCNJ — ©

CST-JLjD 039d0sav ASd3N!3

TEMPERATURE

CF)

12L14

STEEL

Q

O

JOULES

cai-ia) aaadosav ASdaNa

TEMPERATURE

CF5

AXSI

12L14

STEEL

1/2

inch

C38

mm),

Hot

Ro

I

led

©

JOULES

cai-l-d} 038aosav A9d3N3

TEMPERATURE

CF)

Q

JOULES

can-id } G3adosav A9J3N3

TEMPERATURE

CF)

AISI

1

2L

1

-4

STEEL

i

nch

CI9

mm}.

Cold

Finished

SFA

<S

(\J

(\J

C 50 30NVdV3ddV 3dfll3VdJ dV3HS

TEMPERATURE

CF)

ture

Appearance

Temperature

Transition

Curve

CJO 30NVdV3ddV 3dfllOVdd dV3HS

TEMPERATURE

CF)

C\J

OJ

1 . 1 1 I I I I 1 I I G>-O)OOh0WtCOW

©

00

©

— ©

C/O 33NVdV3ddV 3dniOVdd dV3HS

TEMPERATURE

CF)

Shear

Fracture

Appearance

Temperature

Transition

Curve

G>

CM

C\J

C 50 30NVdV3ddV 3dfllGVdd dV3HS

TEMPERATURE

CF>

AISI

12L14

STEEL

1/2

inch

C38

mm),

Cold

Finished

&

Heat

Treated

SFA

CJO 30NVdV3ddV 3dniOVdJ dV3HS

TEMPERATURE

CF>

a.

b.

Figure 9. Charpy V-notch Specimens Exhibiting Changed Fracture "a :e

a. 1-1/2 inch (33 mm) hot rolled bar, Temoerature =

' '4 r b. 3/4 inch (19 mm) hot rolled bars

Top Row: Temperature = 55 F (13 C)

Bottom Row: Left, Temperature = 72 F (22 C Right, Temperature = 123 F (51 C)

kBS*I14A irev. 2-601

U.s. OEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET .See instructions)

1. PUBLICATION OR

REPORT NO.

NBSIR 84-2839

2. Performing Organ. Report No. 3. Publication Date

March 1984

*. IIILfc "NU jU 1 1 1 Lc

Hechanical Properties of a Leaded, Resul fori zed, Rephosphorized Steel in Vari hermo/ Mechanical Conditions dr 1 ous

5. AUTHOR(S)

James G. Early

6. PERFORMING ORGANIZATION (If joint or other than NBS. see instructions)

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

7. Contract/Grant No. Z70099-2-02055

3. Type of Report & Period Covered

Final

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State . ZIP)

U. S. Coast Guard

Washington, DC 20234

10. SUPPLEMENTARY NOTES

J Document describes a computer program; SF-185, FIPS Software Summary, is attached

si gnificant information. „ document includes 0 si gnif,can t The results of the metallurgical evaluation of bar stock samples of AISI 12214 steel in cwo thermo/mechanical conditions, cold finished and hot rolled illustrate the dominant role that the thermo/mechanical condition has on the

n ^

meC

5

aniCal P r°Perties * The contributing effects of ferrite grain size and bar diameter on mechanical properties were small in comparison to the effects

°Ibi«5Ld°?n ^

e

h

C0ld finisbin

? operation. Cold finished bar stock samples

ranertfl

bra

? ln

?

cycle < wlthout the b TMzing alloy) develop mechanics properties that are very similar to those attained in hot rolled bars.

key WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate „e Y wore: , tars, cold finished, cold finished/heat treated, hot rolled, leaded steel reDhrKnhnv'i sphosphorized 7qH 1 steel, resulfurized steel.

Availability

Unlimited

Tj For Official Distribution. Do Not Release to NTIS

204*2 ^ r ° m Superintendent of Documents, U.S. Government Printing Office, Washington. D.C.

,17]0rder From National Technical Information Service (NTIS), Springfield, VA. 22 ! 6 i

14. NO. OF

printed pages

15. P>
.