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QUENCHING CYCLES- OF SOME

ALLOY STEELS
THESIS FOR DEGREE OF MET. E.

JAMES WARD PERCY

1929

 

- QUENCHING CYCLES -

OF SOME ALLOY STEELE

Theeie
Submitted to the Faculty
of
Michigan State College
of Agriculture and. Applied Science
In Partial Fulfillment
of the
Requiremte for the Degree
of

Metellurgieel Engineer

J'enee Ward w

my, 1929.

"i'HESIS

 

 

 

 

- ABSTRACT -
A brief discussion of the development and use of the quench-
ing cycle. 'I'Ielve types of alloy steel, representing three grades in
gemral usage have been examined. The analysés, together with the

hardness data, and the microscopic examination, illustrated by micro-

graphs, are given.

{£3333 “E-

INTRODUCTION

The discovery and subsequent patent of an alloy steel by Ketley
in England in 1799 marked the beginning of a new era in the age-old manu-
facture of steel. Faraday and Stodart helped to pave the way to advance-
ment with their comprehensive study, in 1820. In 1857, Mushet presented
his air—hardening (tungsten) steel. The progress of alloy steel thru the
years is mrked by the names of Hadfield, Riley, Taylor and White, Brearley,
Helouis, and many others.

In the United States, the advance of alloy steel has closely
followed that of the automobile, until today, but a small percentage of
plain carbon steel finds its way into these vehicles.

While the addition of alloying elements, of themselves, do
show a marked effect on the physical properties of the alloy, over that
of carbon steel, that alone would not be sufficient to warrant their
great use. Their real value, in the increase of strength and resistance
without additional weight, has only been brought about by what now is
known as heat-treatment.

Just when and how the art of hardening steel or iron was discovered
will ever rennin a mystery of the past. Homer, in his Odyssey (800 3.0.),
describes how "the glowing are is dipped in cooling water, which spouts,
hardening artfully." Quenching in oil likewise seems to Inve been known
to the Greeks- at an early date. Magnus gave his explanation in the 16th
century - "Water, the principle of fusibility, which occurs in iron, gives

it a certain softness. If the iron is made glowing hot, this most subtle

aqueous part distills away and the rest becomes hardened.”

Without entering into a very detailed discussion of the various
explanations of this phenomena of hardening, which are being offered in
the present day, suffice it to say, that all are based principally upon a
phenomena known as allotropy. This may be defined, simply, as a change in
energetic condition, unaccanpanied by a change of state. If we heat a
piece of pure iron to a high temperature and allow it to cool, observing
the temperature, we find that at about 900° C, an arrest in the cooling
occurs, an indication that a heat production has occurred. This heat
production depends upon a change in energy condition, from the rich to a
poorer. This critical point or recalescence in iron was first observed by
the Swadish metallurgist, Angerstein, in 1778. We find the occurrence of
these transformation points in some pure metals and alloys. Their position
in the scale of temperature is peculiar to the metal, or in an alloy, in its
metallic components and the relative quantity in which they exist. Experi-
ments have shown that the reverse of this transformation and an absorbtion
of heat occurs if the metal be heated instead of cooled.

As has been said, the greatest advantages of alloy steels, their
increased properties, can only be brought about by the use of heat-treatment.
This heat-treatment may not necessarily be one of hardening, but of placing
the steel in a condition most suitable for its particular use. This heat-
treatment can be accomplished only by knowing the exact position of this
point of recalescence in one of the popular scales of temperature measure-
ment. Likewise, it is pertinent that the various changes in metallographic
structm'e, and corresponding specific hardness, preceding and succeeding
these transformations, both from the heating and cooling, approach.

The exact position of this critical point can readily be deter-

mined by laboratory means or by the actual phenomena of recalescence by

the trained observer. However, a practical method of finding all the
necessary data including metallographic structure and hardness for

each specific grade of steel has been devised. This method, for want
of better, has been termed the quenching cycle. It was designed and
worked up after a long series of experiments which had in d: with the
industrial development of various alloy steels. Later, it has been
applied to various phases of mill practice necessary in the manufacture
of steels, for the trade. Likewise, its use has found ready application
by the trade in the fabrication of bars into the finished product, i.e.
that part which has to do with heat-treatment.

The quenching cycle consists of a number of anall pieces of a
given material which have been quenched or cooled in some media from
periodic temperatures which are on an ascending and descending scale
from room tanperature to a point well above the occurrence of the trans-

formation or recalescence. This is more simply explained by the following

schematic diagram.

 

4T »

Units of Temperature

 

 

 

 

£1!

 

Units of Time

The diagram is almost self-explanatory. A—B represents the
heating portion of the cycle, and C-D—E-I, the cooling portion. The
specimens are cooled rapidly in the furnace frmm c to D, since it has
been found by experimce that nothing is to be gained in adhering in
the prescribed rate thru this stage. Upon this diagram, in dotted lines,
has been superimposed a hypothetical inverse rate curve showing the posi-

tion of the critical points.

PROCEDURE

Since the quenching cycle was desiged with a practical pur-
pose in mind, its operation involves but a small amount of material and
me usual equipment found in the average routine laboratory. Of the
steel involved in the experiment, a bar, preferrably one inch in diameter,
about fifteen inches long, is cut up into a nmnber of discs, one fourth
inch in thickness. About forty such discs are necessary.

These discs are identified by a stenciled number and placed
into the laboratory furnace, at rem tanperature. If the temperature of
the furnace be automatically controlled, the experiment will be somwhat
simplified. The furnace used in the preparation of this report was one
manufactured by the Hoskins Manufacmring Canpany, designated as Type
F H sow, electrically heated, and controlled by Brown Ins trtment Germany
equipment. The control equipmnt was adjusted so that the rate of heating
was l°l‘. per minute and the power applied. The specimens were left undis-
turbed until the temperature of the furnace had reached a point about
100° 1‘. below the approximte occurrence of the first transformation
point (Acl). This was usually 13000 I. At this point, the furnace was
opened and the first piece was quenched in water. Care was taken to see
that the piece was properly quenched which included a pre-heating of the
tongs, etc. As the tenperature of the furnace and discs increased, at
every period of 20° 1. and approximately twenty minutes time, one piece
was quenched, until the maximum temperature was reached. This was at
least 200° 1‘. above the last trmforntion point or about 1600" F. The
furnace was held at this mxinum for thirty minutes to insure thorough

solution. The temerature was then dropped from 150° to 300° at the rate

of 150° per hour. It was learned after several trials that but little

could be gained by slower cooling through this range. A point about
150° above the first decalescence point is now reached. The furnace
control is adjusted so that the rate of cooling is 1° F. per minute.
Periodically at every 80° F., a specimen is quenched, as in the first
part of the cycle, until the end of the cycle is reached. This usually

is about 200° F. below the last decalescence point or about lOOO° 1'.

These specimens, representing a quench from every periodic
temperature ascending to and descending from the maximum, were then
carefully prepared for the hardness determination. About .030” of one
flat side of each disc was removed by grinding. This was done to
remove all scale and decarburization of the metal incident to the heat-
treatment. By means of a standard Brinell machine, manufactured by the
Aktiebolaget Alpha of Swaden, the Brinell number of each piece was deter-
mined. The impression was made by a 10 m. ball under a load of 3000 kg.
applied for 50 seconds.

After this data had been compiled, these same sections were
prepared for micro-examination. Under the microscope, the changes in
structure could be followed readily. To properly illustrate these
changes for each cycle, at least four micrographs were found to be
necessary and these have been included in this report. These were taken
on a Leitz Metalloscope at the location and magnification indicated.

(1) 100° 1". below first transformation, heating cycle, at 100 diameters.
(2) at the first critical point Acl, heating cycle, at 500 diameters.
(3) at the point of maximum hardness, the A03 point. at 500 diameters.

(4) below the Arl point, cooling cycle, usually the point of lowest

hardness at 100 diameters.

DISCUSSIOE
In this report, three grades and twelve types or analyses of

alloy steels have been considered. These are tabulated below:

 

 

GRADE TYPE SYMBOL ANALYSIS
Carburizing S.A.E. 2315 3.5% Nickel .15% Carbon
" " 8512 5.0% 7 .1276 "
" " 3115 1.5% Ni. -.75% Gr. .15% "
" a 4.615 1.5% Ni. -.25% Moly. .15% v
Water Hardening " 1350 1.5% Manganese .30% "
" " 2330 3.5% Nickel .M "
" " 3130 1.5% Ni. «75% Or. .3095 "
v' " 4130 .7596 Or. «20% Moly. .30% "
Oil Hardening " 8540 3.5% Nickel .M "
' " 3140 1.5% N1. -.75% Gr. .40% "
" " 5140 1.0% Or. .505 '
" " 6140 1.0% Cr. -.15% Va. .401 "

The type symbols used are those of the Society of Automotive
Engineers and are conventional in the United States. The analyses
indicated are of the major elements only and represent the mean of the
range specified by the above organization. The analysis of the mterials
used will be found to vary but slightly from these mean values. These
three grades were picked since they represent the three chief methods of
heat-treatment in general usage today. The type of steels chosen for this
report were taken as the ones most generally used in this country under
the conditions of heat-treatment indicated. The relative merits of these

types in each grade do not enter into this discussion, since individual

fabricators express a preference for varying reasons, such as machin-
ability, uniformity, sensitivity to heat-treatment, tensile strength,
cost, etc.

On the following pages, each of these types, in the order
mentioned, will be discussed. This will include the analysis, hardness

data, and a brief description of the changes in microscopic structure

together with the four micrographs, for each cycle.

Quenching Cycle No. l.
Carburizing Grade .

Type - 3.11.12. 2:515 - 3-1/27; Nickel.

 

 

Analysis:
Carbon Manganese 3311591
.15% .52% 3.58%
Hardness Data: »
HEATING PHASE COOLDIG PHASE
Brinell Brinell
Test Quenching Temperatm‘e Number Test Quenching Tanperature Number
113-1 12800 r. 170 17 14000 r. 564
2 1500 185 18 158) "
5 1520 207 19 1560 "
4 1540 212 20 154.0 "
5 1560 228 21 1520 "
6 1580 r 241 22 1500 540
7 1400 248 25 128) "
8 1420 268 24 1260 521
9 1440 285 25 1240 277
10 1460 56‘ 26 1220 262
11 14.80 56d 27 1200 248
12 1500 564 28 1180 217
15 1520 564 29 1160 211
14 1540 554 50 1140 207
15 1560 564 51 1120 106
16 15m 564 52 1100 174

MICROSCOPIC EXAMINATION:

Refer to Fig. l, 2, 5, 4. Fig. 1 represents the metallograph-
ic structure found at 100 diameters in Test No. 2 of the series. It is
one of fine grained pearlite and ferrite, typical of all conditions below
the transformation point. Fig. 2 illustrates the condition found just
within the critical range, Test No. 7, at SOD-X. This structure is that
of troosto-sorbite, sometimes known as Oemondite. The white areas are
ferrite. Fig. 3 is the metallographic structure of Test No. 11, at a
point just above the transformation. The condition is one almost
entirely martensitic with a very thin matrix of retained alstenite (white)
indicated. Fig. 4 rQresente Test No. 52 of the series, at loo-x. T13
condition is similar to that found in fig. 1, pearlite and ferrite, of a
somewhat larger grain size. All of these specimens were etched with a

5% solution of nitric acid in alcohol, nital etch.

 

Quenching Cycle No. 2.

Carburizing Grade .

 

 

Type - 3.1.1:. 2512 - 5% Nickel.
Analysis:
m Manganese $2591
.12% .412 5.07%
Hardness Data:
‘ HEATING PHASE COOLING PHASE
Brinell Test Brinell
Test Quenching Temperature number Quenching Temperature Number
Z-l 12800 r. 217 Z-l? 14000 r. as.
2 1500 241 18 1580 564
5 1320 241 19 1560 364
4 1340 241 20 1540 364
5 1560 269 21 1520 564
6 158) 295 22 1500 564
7 1400 552 25 1280 564
8 1420 540 24 1260 564
9 1440 540 25 1240 564
10 1460 551 26 1220 564
11 14% 564 27 1200 540
12 1500 564 28 1180 521
15 1520 564 29 1160 cos
14 1540 564 50 1140 255
15 1560 564 51 113) 28
16 158) 564 52 11.00 217
35 1080 307
54 1060 189

MICROSCOPIC WATION:

Refer to Fig. 5,6,7,8. Fig. 5 illustrates the condition found
in Test No. l of this series. It is a structure of ferrite and some
pearlite, very fine grained. The micrograph is at loo-x. Fig. 6 is
that (1’ Test No. 5 at 500-1. The condition is troosto-mertensitic with
large white areas of ferrite, e11 grains well defined. This is the con—
dition within the transformation range. Fig. 7 is the micrograph of
Test No. 12 at 500-1. The structure is that of coarse martensite. Note
the slight retention of austmitic grain boundaries as well as that of
some austenite. Fig. 8 illustrates the cooling phase of the cycle well

before the Ar.1 point, Test No. 54 at 100-1. The structure is one of

uniform fine grains of pearlite and ferrite.

Quenching Cycle No. 5.

Carburizing Grade.

 

 

Type - S.A.E. 5115 - Nickel—Chromium
Analysis:
_(_3_a_l:~_b_o_l_l_ Mang one as M Chromium
.172 .6075 1.32% «52%
Hardness Data:
HEATING PHASE COOLING PHASE ‘__
Brinell Brinell
Test Quenching Temperature Number Test Quenching Tamperature Number
on 15000 r. 165 v.17 14000 r. 521
2 1520 165 18 1580 502
5 ' 1540 179 19 1560 295
4 1560 255 20 1540 262
5 1580 279 21 1520 255
6 1400 286 22 1500 228
7 1420 . 502 25 1280 217
8 1440 521 24 1260 202
9 1460 564 25 1240 149
10 1480 " 26 1220 145
11 1500 1' 27 1200 w
12 1520 " 28 1180 "
15 1540 7 29 1160 ‘
14 1560 " 50 1140 7
15 1580 " 51 1120 ”

16 1600 ” 52 1100 140

MI CROSCOPI C EEQMINATI ON :

Refer to Fig. 9, 10, 11, 12. Fig. 9 represents the metallo-
graphic condition found in Test No. 1, of the series at 100 diameters.
The structure is one of a medimn-sized grain of dense pearlite and
ferrite. Fig. 10 was taken of Test No. 4, at 500-X, and illustrates the
condition just within the hardening range. It shows dark areas of sor-
bitic pearlite with white areas of ferrite. Fig. 11 slows the structure
found at 500-1 of Test No. 10 of the series. It is martensitic with
quite an amount of retained anstenite, the white areas. Note the rounded
sides of the dark areas, showing the relatively close proximity of a
troostitic state. Fig. 12 was taken in the cooling phase well below the
critical range. -Tegt No. 37, Again we find pearlite and ferrite, in well

defined grains, and uniform.

 

Quenching Cycle No. 4.

Carburizing Grade .

Type - S.A.E. 4615 - Nickel - Molybdenum.

 

 

 

Analysis:
9.3.2.5122 Langme se Nickel Molybdenum
.17‘ .465 1.59% .27$
Hardness Data:
HEATING CYCLE COOLING CYCLE
Br incl 1 Brinel 1
Test Quenching Temperatm'e Number Test Quenching Temperature Nimber
3-1 1500" r. 185 53-17 1400° r. 418
2 1520 187 18 1580 587
5 1540 207 19 1560 564
4 1560 262 20 1540 517
5 1580 511 21 1520 286
6 1400 521 22 1500 2'77
7 14m 541 25 12% 269
8 1440 551 24 1260 255
9 1460 556 25 1240 228
10 14% 564 26 1226 218
11 1500 579 27 1200 207
12 1520 418 28 11% 179
15 1540 418 29 1160 165
14 1560 418 50 1140 156
15 1580 418 51 112) 149
16 1600 418 52 11.00 149

MICROSCOPIC EXAMINATION:

Refer to Fig. 15, 14, 15 8:. 16. These four micrographs re-
present the cyclic changes of this series. Fig. 15, of Test No. l,
at loo-x, shows a granular state of sorbitic pearlite and ferrite. The
grains are somewhat ill-defined. Fig. 14 shows the state of Test No. 4
at 500-1. Here we find a troosto-martensitic condition with considerable
free ferrite. Fig. 15, also at 500-X, is that of Test No. 12. This
condition is typical above the critical point. It is almost entirely
martensitic with a mall amount of retained austenite. Fig. 4 is sane-
what different from that of Fig. 1 in this series. The structure is
that of Test No. 50 at loo-x. It is of uniform nedium-sized grains of

pearlite and ferrite.

v.5.
w
.

. .z.
. L

. me...

 

Quenching Cycle No. 5.

Water-harden ing Grade .

 

 

Type - S.A.E. 1555 - Carbon Manganese
Analysis:
w N anese Silicon
.5475 1.72% ”22%
Hardness Data:
HEATING PHASE mOLING PHASE
Brimll Brinell
Test Quenching Temperature Nmber Test Quenching Temperature Number
I-l 1.300" r. 187 1-15 14m° r. 512
2 mm 187 16 1400 512
5 1540 196 17 1580 512
4 1560 502 18 1560 512
5 1580 587 19 1540 477
6 1400 450 20 1520 477
7 1420 444 21 1500 477
8 1440 444 22 1280 444
9 1460 460 25 1260 450
10 1480 512 24 1240 418
11 1500 512 25 1220 587
12 1520 512 25 1200 564
15 1540 512 27 1180 179

1520 512 28 1160 179

5:

MICROSCOPIC MMJINATION:

Refer to Fig. 17, 18, 19 & 80. Fig. 17 slows a rather unusual
condition. This was taken of Test No. 2, at ioo-x. It represents a
condition below the critical heating phase. It is one of very fine
grained sorbitic pearlite and free ferrite. Fig. 18 shows the metallo-
graphic structure of Test No. 4 of the series, at SOC-X. This structure
is one of pearlitic sorbite, with some free ferrite in well defined
grains. Fig. 19 is of Test No. 11, at 500-1. Again we find mostly
martensite, Just short of the acicular condition. This is the state
typical above the critical. In Fig. 20, vhich is representativeiof
Test No. 27, at 100-X,'I0 again find a condition of equilibrium. Th1:
is a fine grained dense sa'bitic pearlite and ferrite, intermixed. The

grain boundaries are well defined.

 

Quenching Cycle No. 6.
Water-hardening Grade.

Type - SeAeEe 2530 "" 3-1/27?) NiCkele

 

 

 

Analysis:
£259.99. Msngane s e M3];
.32% .5973 3 «12%
Hardness Date:
HEATIN‘: PHASE COOLING PHASE
Brine ll Brinel 1
Test Quenching Temperature Number Test Quenching Temperature Number
B-l 1220° r. 207 2-13 1300° r. 332
2 1240 207 17 1280 532
3 1260 207 18 1260 532
4 1280 223 19 1240 512
5 1300 241 20 1220 444
6 1320 ‘ 340 21 1&0 444
7 1340 418 22 118) 430
8 1360 477 23 1160 .402
9 13m 495 24 1140 340
10 1400 512 25 11m 205
11 1420 512 26 1100 179
12 1440 512 27 1030 179
13 1460 532 28 1060 174
14 1480 532 29 1040 166

13 1500 ' 332 30 1020 133

MICROSCOPIC EXAMINATION:

Refer to Fig. 21, 22, 23 8c. 24. Fig. 21 represents the struct-
ural condition of Test No. 3 at loo-x. It is a rather non-uniform grain
of dense sorbitic pearlite interspersed with some free ferrite. Fig. 22
is of Test No. 6 at 500-1. It represents almost true Osmondite. We find
some free ferrite together with sorbitic troostite, Careful examination
shows some slight evidence of the formtion of martensite. This micro-
graph represents a condition found rather infrequently, especially in this
type of steel. Fig. 23 shows trs structure usually found about the criti-
cal in all types of steel. It is of Test No. 14 at 500-1. Il'he structure
is that of coarse mrtensite. Note the retention of the anstenitic grain
boundaries. Fig. 2A is of Test No. 28 at loo-x. It is a structure of very

fine grained pearlite and ferrite, rather unifom.

    

Fig.22.

Quenching Cycle No. 7.
Water-hardening Grade.

TYPO - SeAsno 31m "’ N1Ckel Chmmiumm

 

 

Analysis:
9.933123 Magane se W Chromium
20% .65% 1.18% .372
Hardne e 3 Data:
HEATER} PHASE COOLINC: PHASE
Br iml l Bri nel 1
Test Quench ing Tempe ratln'e Numbe r Test Quenching Temperature Numbs r
am. 12800 r. 179 1:43 1300" r. 477
2 1300 179 16 1340 477
3 1320 187 17 1320 444
4 1340 187 18 1300 402
5 1360 223 19 1280 364
6 1380 340 20 1260 196
7 1400 387 21 1240 179
8 14.20 444 22 1220 174
9 1440 460 23 1200 170
10 1460 477 24 1130 170
11 1480 477 25 1160 170
12 1500 477 26 1140 170
27 113) 170

MICROSCOPIC EXAMINATION:
Refer to Fig. 25, 26, 27, &.28. The first of these, Fig.

25, is a micrograph of Test No. 4 of this series, taken at 100-1. It
is a structure of fine pearlite, with grain envelopes of ferrite. The
grains are medium-sized and well defined. Fig. 26 is of Test No. 6 at
500-1. The condition is troosto-martensitic, chiefly the latter, and
represents the structure found well up in the hardening range. Fig. 27
is similar to the structure found in most hardened untempered steel of
this carbon content. It is largely martensitic, almost acicular. The
micrograph is of Test No. 10, st 500-1. Fig. 28 is of Test No. 24 at
100-1. It represents a condition of'mstasteble equilibrium, 1. e. fins

pearlite and free ferrite of rather small grain.

   
 

Fig .26 0

Fig.2?.

Quenching Cycle No. 8.
Water-harden ing Grade.

Typo - 30A one 4130 - cmomm-MOhbdonme

 

 

 

Analysis:
£95593 Manganese Chromium Molybdenum
.321. .5293 .64% .22%
Hardness Data:
EATING PHASE COOLING PHASE
Br inell Brinell
Test Quenching Temperature Number Test Quenching Temperature Number
0-1 1300° r. 170 0-13 ‘ 14200 r. 512
2 1320 179 16 1400 495
3 1340 179 17 138) 418
4 1360 183 18 1360 418
5 13m 196 19 1340 364
6 1400 255 20 1320 364
7 1420 418 21 1300 207
8 1440 477 22 1280 170
9 1460 477 23 1260 170
10 143) 477 24 1240 170
11 1500 512 25 1220 170
12 13m 512 26 1200 170

MICROSCOPIC.EXAMINATION:

Refer to Fig. 29, 30, 51 8: 32. The first, Fig. 29, is at
100-1, of Test No. 3. This structure is one of sorbitic pearlite and
the needle-like arrangement of grains is somewhat peculiar to the type
of steel among others. Fig. 30 is of Test No. 6 at 500-1 and indicates
the general structure well up in the critical.range of temperature. It
is one of troosto-martensite. Nets the beginning of the needUe-like form-
ation peculiar to martensite. The structure is somewhat coarse. Fig. 31,
also at 500-1, is of Test No. 12. This is a.martensitic condition with a
small.amount of retained sustenits showing through. Fig. 32 is of Test
No. 24 at 100-1. Again, we find the usual structure of dense pearlite and

free ferrite, well defined.

 

QUENCHING CYCLE N0. 9.
Oil-Harde ning Grade .

Type - S.A.E. 2340 - {kl/2% Nickel.

 

 

 

Analysis:
we. ”21128111939 M
.4473 32% 3.38%
Hardmss Data:
HEATING PHASE COOLING PHASE
Br inell Brinell
Test Quenching Tanperatire Number Test Quenching Temperature Number
T-l 124o° r. 223 T-16 1330° F. 300
2 1260 223 17 1340 600
3 1280 228 18 1320 578
4 1300 302 19 1300 578
5 1320 321 20 1280 578
6 1340 495 21 1260 578
7 1360 578 22 1240 5'78
8 1380 600 23 1220 555
9 1400 600 24 1200 512
10 1420 600 25 1180 477
11 1440 600 26 1160 477
27 1140 286
28 1120 196

29 1100 196

QUENCHING CYCLE NO. 9.

Oil-Hardening Grade.

Type - 3.1.3. 2340 - 3-1/22 Nickel.

 

 

 

 

Analysis:
.JEEEEEL. Nhnganese _§lpkel
.444 452% 3.38%
Hardness Data:
HEATING PHASE COOLING-PHASE
Brinell Brinell
Test Quenching Twmperature Number Test Quenching Temperature Number
T-l 1240° 17. 223 T-16 1350° F. 600
2 1260 223 17 1340 600
3 1280 228 18 1320 578
4 1300 302 19 1300 578
5 1320 321 20 1280 578
6 1340 495 21 1260 578
7 1360 578 22 1240 578
8 1380 600 23 1220 555
9 1400 500 24 1200 512
10 1420 600 25 1180 477
11 1440 ' 300 26 1160 477
27 1140 286
28 1120 196

29 1100 196

MICROSCOPIC EXAMINATION:

Refer to Fig. 33, 34, 35 & 36. The first of these is of Test
No. 1 at lOO-X. The structure is a granular condition of fine sorbitic
pearlite surrounded for free ferrite. The grain boundaries are definite.
Fig. 34, at 500-X; is of Test No. 5 of the series. Here we find Osmon-
dite, i. e., troosto-sorbite, with a sma ll amount of free ferrite inter-
spersed. Fig. 35, also at 500-X, is of Test No. 9, which is rather well
up above the critical range of temperature. Themartensite is acicular,
very slightly tempered. The last micrograph, Fig. 36, of Test No. 28, is
at lOO-X. This is near the bottom.of the cooling phase. We find.dense
pearlite and ferrite in a rather stable condition, well defined uniform

grains. Note that the ferrite is more freely dispersed than in th. 33.

459‘“. I v-K.‘
. a - . " .
i; ,- {fknv '-‘ .
‘4‘: ‘L‘t' 0), i w.:-‘ :

‘ 51. "if?!

r‘ .9152”? "
%M‘ _' I' S '

 

Fig.35o

Quenching Cycle No. 10.
Oil Hardening Grade.

Type - S.A.E. 3140 -Nickel-Chromium.

 

 

Analys is :
923113.11 mega W ”Ch? 01‘1qu
.437; .6475 1.18% .56%
Ear dne s 3 Data :
IEATDTG PHASE CC OLDTG PFJiSE
Br ins l 1 Bri ne 11
Test Quench ing Temper atur e Number Tee t Que nch ing Temperature Numbe r
F-l 1280° F. 217 F-16 1340° 13*. 5'78
2 1300 217 17 1320 555
3 1320 217 18 1300 555
4 1340 241 19 12m 512
5 1360 2’77 20 1260 £44
6 13a) 512 21 124) 241
7 1400 537 22 1220 196
8 1420 555 23 1200 196
9 1440 555 24 1.1% 196
10 1460 555 25 use 183
11 143) 555 26 1140 183
12 1500 578 2'! 1120 183
13 1520 5’78 28 1.100 183

MICROSCOPIC mmmTiEON:

Refer to Fig. 37, 38, 39 8c. 40. Fig. 3'7 of these four micro-
graphs is an illustration of the condition found in Test No. 2 at 100-1.
We find the usual condition of dense sorbitic pearlite with a network
grain houndary of free ferrite. In Fig. 38, which is of Test No. 5, at
500-1, we again find the transitory stage, but rather low in the range.
Here we observe a sorbitic troostite rather poorly defined, in a ground
mass of what appears to be ferrite. This structure might well be termd
a primary Osmondite. In Fig. 39, we find an illustration of the structure
found in Test No. 9 at 500 diameters. Here we find rather coarse acicular
martensite in a ground mass of austmite. This, of course, is typical of
the hardened state. Fig. 40 is of Test No. 26 at loo-x, much similar to
the first micrograph of this series. We again find pearlite and ferrite

with the latter well and uniformly dispersed, due to the slow cooling rate.

 

Fig.38.

'“j'tftflg’da- .,
‘. -. ' fi‘K. ":. D.

-: sweat

Quenching Cycle N0. 11.
Oil Hardming Grade.
awe - SOAOIO 5140 -

Analysis :

Carbon

«14%
Hardness Data:

HEATING PHASE

 

Test Quemhing Tampa-attire Number

.T-l 1300" r.
2 1320
3 1340
4 1360
5 1380
e 14.00
7 1430
e 1440
9 14.60
10 1480

1500

t:

 

1% Chromium.
Nbgganese Chromium
.859: .98%
COOLING PHASE
Brinell Brinell
Test Quenching Temperature Number
217 .T-18 1360° r. we
223 19 1340 578
228 so 1320 512
2A]. 21 1300 241
286 22 123) 196
341 23 1260 196
477 24 12110 196
578 25 1220 196
578 26 1200 196
578 2'] use 187
578 28 1160 18?

MICROSCOPIC EXAMINATION:

Refer to Fig. 41, 42, 43 and 44. In Fig. 41, which is Test
N0. 2 at 100-x, we find the usual pearlitic-ferritic condition. The
ferrite is rather uniformly dispersed. In Fig. 42, we examine Test No.
4 at 500-X. Here we find a rather unnmal condition, pecu1iar to this
steel. We find the ferrite network, very large grained. We find a sor-
bitic condition with a great tendency toward spheroidization and tin
fennation of carbides, or double carbides. This coniition is usually
found in the critical range, which range is very narrow and often over-
looked. Fig. 43 is of Test N0. 9 at 500-1. Nothing unusml is noted
except that a comparatively large ammnt of retained austenite is present.
Fig. ‘4, of Test N0. 23, at 100-1, is very much similar to mat of Fig. 40.

The grain size is somewhat larger, but not as well defined as in the

fomr.

 

Quenching Cycle N0. 12.

011 Hardening Grad. .

Tm, "' SeAeEe 61‘0 "' Chmmi‘m' Vanadium.

 

 

 

Analysis:
221119.33. Mangane se Chromium Vanadium
.421 .75 1.09% 49%
Hardness Data:
HEATED PHASE COOLING BIAS!
Brinell Brinell
Test Quenching Temperature Number Test Quenching Temperature Nimbu-
M-l 1300" r. :77 M-rr 1430" r. we
2 1320 269 18 1400 555
3 1340 255 19 133) 477
4 1360 241 so 1360 444
5 13m 235 21 1340 418
6 1400 223 22 1320 269
'7 1420 255 23 1300 187
8 1444 402 24 12% 187
9 14.00 ' 477 25 1260 187
10 1480 4'77 26 1240 187
11 1500 512 21 1220 187
12 15m 512 28 1200 187
13 1540 532 29 um 18']
14 1560 532 50 1160 18‘!
15 15% 555 31 1140 18'!
16 1600 555 32 11:0 179

Quenching Cycle N0. 12.
Oil Hardening Grade.

Type - 8.A.E. 6140 - Chromium- Vanadium.

 

 

 

Analysis:
2933.22 Mangane se Chromium Vanadium
.42; .731 1.09% .19%
Hm‘dness Data:
HEATED PHASE COOLING PHASE
Brimll Brimll
Test Quenching Temperature Number Test anohing Temperature Nmber
M-l 1300" r. :77 1.1-1? 1430° r. 505
2 1320 269 18 1400 556
3 1340 253 19 1380 4'77
4 1360 241 20 1360 444
5 1380 235 21 1340 418
6 1400 223 22 1320 269
7 1420 255 23 1300 187
8 1444 402 24 12% 187
9 14.00 ' 477 25 12.00 187
10 1480 477 26 1240 18?
11 1500 512 27 1220 187
12 1620 612 28 1200 187
13 1540 532 29 118) 187
14 1560 532 30 1160 187
16 1580 656 31 1140 187
16 1600 555 32 1130 1'79

MICRwOOPIC EXAMINATIOI:

Hefer to Fig. 45, 46, a a. 48. The first of these, Fig. 45,
depicts, at 100-1, the structure found in Test No. 5 of the series. Here
we find pearlitic sorbite, with file granular network rather ill-defined.
What little free ferrite remains is in a very finely divided state. In
Fig. 46, we have the structure of Test N0. 8 at 500-1. Again we find a
good specimen of the so-called Osmondite, in which we find sorbitic
troostite with some little martensite poorly formed. In Fig. 47, also at
500-1, we examine Test No. 16, which is well above the critical point in
the heating phase. Here we find, chiefly, martensite, with a very little
retained austenite. In Fig. 40, which is of'Test No. 20, at 100-1, we can
to the common condition, found in this portion of the phase. Here we find

dense pearlite with free ferrite, uniformly dispersed thrueut.

Ju. I'l’f'jfj‘é’. 1.

o
a ("I I,‘

., u'- v.\vb,u_e . ”‘tg .-.-

.55., . _
‘14 1.2311319)? : 9‘32}? "‘ ‘ '

,{nél‘u . r5
in x -

 

_ SUB/It" ..

The better to present the large amount of data given in this
report, a series of graphs have been constructed and are to be found below.
Three pages are given, one for each grade of alloy steel discussed. On
each page, are found four curves, which represent each type of material in
that particular grade. The type and curve have been designated by the con-
ventional numbers assigned by the Society of Automotive Engineers.

The curves themselves are almost self-explanatory. The Brinell
numbers have been plotted against the quenching temperatures in degrees
Fahrenheit. A close examination will show that the middle ordinate on the
sheet is really a dividing line, since it separates the heating and cooling
phases of the cycles. It will also be noted that this ordinate likewise
”rue for two values, 1600" r. and 14000 3. being the end of the heating
and beginning of the cooling phases, respectively. In order hat the
separate curves may be the more clearly seen both solid and brok6n lines
have been used.

The individual graphs need but little conment. In its series on
the carburizing grade, three types have the same maximum hardness. The
nickel molybdenum, S..A.E. 4615, shows a sanewhat higher maximum. However,
the actual hardening range is about 100° shorter than those of the other
three types. The curves, in shape, are very similar, especially in three
curves. In the S.A.E. 4615, the appearance of the 161 transition point or
the beginning of the hardening range is much more distinct. This feature
is peculiar to this type, along with several other types.

The second sheet of graphs represents the water hardening gade.

Here the 8.1.E. 2330, 3-1/2% Nickel shows the highest maximum Brinell

number. It also shows the broadest hardening range. For these two reasons,

it has been adopted by the automotive trade for a great many uses. We would

 

 

Number

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200 x
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QUE'C' no CYCLE or sort? ALLOY sms
whammy-mm cat-.31.:- \
100
1300 1400 1500 1600 Cooling Phase
Heating Phase 1400 1.500 120- 1100

- . .. n,
wuenc:1ns Temperature

600

 

 

 

 

 

171...“... \3‘
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E I i I], §\ 3‘ §\ ' 3
5;, II \\
I I I; 1‘ \ \
I ' x a \

 

 

 

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.—-—- “" A ’
,— ‘. “rd. -—-— A

.——-1

7"

mums CYCLES do 30‘"? um? scan 3.
-OIL amount-c.

 

 

 

 

 

 

 

 

manna;
100
1300 1400 1o00 1600 Cooling Phase
Heating Phase 1400

1300 1200 1100
Quenching Temperature oF.

 

 

 

 

Number

 

 

 

300 F/

 

 

6
O
\
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l/
7/

 

Brinell
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200

 

 

 

 

amok-'11:; creme OF 30an ALLOY sums

   
  

 

 

 

 

 

 

 

-WATER . ENING—
-G '
133 ‘
loo; 1400 1500 1600 Cooling Phase
Heating Phase 1400 1300 1200 1100

Quenching Temperature oF.

call attention to the curve shown by the solid line, S.A.E. 1330. It
differs but little in appearance from.that of the 3-1/2% nickel. This

type is coming into greater prominence at the present tine, largely because
of its reduced cost, and general adaptability.

The third sheet of graphs represents the oil hardening grade.
The maximum.Brine11 numbers are considerably higher than those of either
of the preceding pages. In general, the curves are very similar. Again
we find that the 3-1/2% Nickel.grade shows the greater hardness as well as
the broadest hardening range. This type, too, is used considerably by the
automOtive industries largely because of these two advantages which lend
to rapid handling and treatment in production.

In the preceding pages, we have attempted to carry on the work:
and collect and present the data in such a way that it might find a ready
practical use. We make no specific mention of its application. The data
on the heating phase should find its place in the heat-treating of the
material where hardness, wearing quality and physical properties are of
essential importance. This applies more particularly to the two grades of
higher carbon content. The cooling phase data should find application in
all process where lower hardness is essential. This covers all annealing
and normalizing which may precede cold drawing or machine work, cold work-
ing, such as bending, forming, and upsetting. The micrographs were made,
the better to illustrate the metallographic structural changes which take
place, and which should be taken into consideration by one who is fully

aware of their importance in adaptation.

E

on-
Uni,

 

 

—_

MICHIGAN STATE UNIVER ITY LIBRARIES

I III I IIIIII I II

3 1293

3142 8714