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THESIS

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THESIS

A STUDY OF CASE HARDENING COMPOUNDS
AND THEIR RELATIVE CARBONIZING ABILITY

A 'THESIS SUBMITTED TO THE
FACULTY OF TiE
MICHIGAN AGRICULTURAL COLLEGE

BY
3° Mf. JOHNSON & A. il, ATZENHOFFER

CANDIDATES FOR THE DEGREE OF
BATCHELOR OF SCIENCE

JUNE 1016,
a

THESIS

 
DISCUSSION

Case hardening must be cenducted with certainty and uni-
fermity., Greater unifermity is ebteined when the cempesitien ef
the metal being heat treated is net changed inside the case, The
details ef this eneratien must be understeed t: the end that the
eperatien may be cenducted with the minimum cest and with the
maximum certainty, Investigations have preven that, cemmercially,
the case carbenizing eperatien can be prerfermed in such a manner
that the final result will be abselutely uniferm.

Our experiments were merely fer the purvese cf determining
the mest efficient ef the different cempounds tested, In eur
cenclusiens we have considered all the phases in ccmmercial
werk which tend te discriminate fer er against the cempeunds,
What we determined as the mest efficient might net preve the
mest ecenemical beceuse of the varying price, However, frem eur
resulta the ecenenical ene ceuld be picked sut when the price

ef each was considered,

OBJECT
The ebject ef this thesis was te test different carben-
izing cempeunds in regard te thelr cenductivity, shrinkage after
a number ef runs, relative cerbenizing abelity, and their general
behavier in racking in regard te dustiness, etc,
The scheme fel'ewed was te pack uno five different bexes,
each ene centainin: a dif‘erent cempcund, Eight pieces were

packed in each bex fcr esch run, After ech run the shrinkaze was

10024’
neted and a sufficient ameunt sf new carbenizer was added each
time te fill un the bex again, The new was mixed thor-ly with
the eld each tire, The runs were made ef a uniferm length of

eight heurs, the temperature being kept c:nstant at 1725 Des, F,

REFERENCES

As preliminary werk several beoks were studied, mamely:
The iietallegraphy ef Iren and Steel, by Sauvier; Cempesitien
and Heat Treatment ef Steel, by Lake; The tietallurgy ef Steel,
by FW. Harberd; Rerert en Case Carbenizing in A. S.M. FE. ef
December 1912, by M. T. Lathren,

Our cerbsnizing and heat treating was dine at te heat
treetin;; plant of the Ree  t-r Car C5, end we are very much
indebted te ir, Carl Nilsen ef that department fer his aid and
valuable suggestiens. The engineering denartment ef the abeve

cemmany very kindly let us use their -icro-phet.:-eter outfit alsc,

CARBONIZING COMPOUNDS
We received c:mn-eunds from the foll:win,, cempanies:
Perk Chemical Ce., Detr it; Blaich Chemical Ce., Chicecze,
Besides these the Ree furnished us with the Ajax cenreund
which they are using, Behnite, and lleusghten cempeunds, The cem-

peunds wre desi-nated by the letters A, B, ~, D, and E,
STEEL

Steel used was ef twe sizes- 3/4" and 1'°2" being or-
dinary mac'iine steel ef .25 carben, This steel was frem the
Ree's preduction steck, and was centered a d turned tie size
befere using.

The whele werk was cone wlth regard te cemmercial practice
as near'y as pessible and is the methed fellexved by heat treat-
ing plants in determining the cemmerci2al econeny ef different
cempeunds,

SHRINKAGE

Each cemvneund was checked fer weight rer cu, ft, first,

In deing this we used a stonderd measure which held <ne cu, ft,
and weighed it filled with cempeund, The vreicsht ef cenpeund

used fer packing was neted “nd als: volume, After the run the
cempeund left was weifhed end volume nected, The velume was kept
constant -t 6°" cu, in. fer each run, Thus we ceuld ebtain the
shrinkage easily for beth vslume and weight in 7%, This was done ‘
after each run fer the six runs, We als: noted the relative

dustiness, ‘these results will be fzund in table "“S fellewing,

PACKING
As stated abeve there were eight pieces, 4 1/2":nd 4 3/4",
packed in each bex abeut half way down in the box and abeut ene-
half tneh between each piece, The bexes were shook dewn well
and cevers -ut un, beings cemented in with clay and asbestes

packing,
FURNACE & RUN
The furnace was ene ef several of its kind used in Ree heat
treating plant in their preductioen werk, The furnsce temnerature
1a electrically centrelled fren the effice and thus kept con-
stant, Our bexes were nut in and left in eisht heurs, which is
the average length ef run en all kinds ef werk, The temperature

was kept at a constant temoerature ef 1725 De, F,

CHEMICAL ANALYSIS

We teck ene sample ef each run fer each carbenizer and teek
feur cuts ef 10/107? each eff each piece, Each cut was cellected
in an envelepe and marked as fellews: Aja, A.b, Aic, Aid; this
being the feur cuts ef carbenizer A,run “1. This gave us a san-
ple fer each zone ef the case and enabled us te get the carben
distributien fcr each run and cemnare the carbonizing effect ef
different corp-unds, The carb:n analysis wos dene by the con-
buaticn methed, The disrram ef the set ur is snam in Biue print
#1, and dees not need a detailed descr'stien, A temrerature ef
abeut °75 fe;. C, was maintained in the furnace, The steel rests
in beats filled wit: R.R, alundum scnd, It teek on an average
ef abeut five -inutes fer each analysis but we had censiderable
difficulty with the beats breaxing frecuently. We ebtoined
eneugh runs, hewever, te get a geod comncrisen ef the different

cempeunds, Results tabulated in table 1,
DEPTH OF CASE,

Next we tek a small plece ef each of the samples used in
analysis, These pieces were semi-circular and abeut ene-quarter
ef an inch thick, These were given a high rzlish and then etched
with Nitric Acid, This breught eut the case plainly and we
measured its derth by means wef Hicra-photeneter eutfit and checx-

ed it by a -icrescenic reading, Results tabulated in table “2,

CONDUCTIVITY

A cenductivity test was run en each c.-mposund by means ef a
lead pet and nyrometer, This csve us the time it takes each ccom-
pound te c.me up te the required heat, The arrangement ef arna-
ratus is sh:wn in Blue print "2, The receptacle fer the cen-
peund was 4" in disneter by 15" nigh, The therme-ceuple was
inserted abeut half way dewn inte t':e recertacle, The pyrcmeter
used was checked against the vyrcmeter of the lead pet, The
lead pet was breught up te abeut 1600 Des, F, and the receptacle
inserted, headings ef the ryremeter were taken every five min-
utes up t. the peint when beth read the same, Results in tables

i 3, 4, & S - clse curves in Blue print 3,
Carbenizer,
ist, .O1
2nd, "
3rd, "
4th, "

Carbenizer,
dst, ici
end, "“
5sra, "
4th, "“

Carbenizer.
ist, .c1
end, "
srd, "
4th, “

Carbenizer,
ist, O21
ond, "
ord, “

4th, "

PERCENT OF CARBON,

(

oteel--- ,25 Carben!,

ist Run,
A, B,
81 1.03
877
2595
et 41
and Run,
A, B,
1,00 1,07
786
ee
2O7E 044
Srd Run,
A, B,
owl oe
0007
045
206 40
4th Run,
A, B,
~29 1,78
eVO
41 290

05

04%

200

1,0°

TABLE

i

ran
cD
td

1,74

oor

# 1,
5th Run,

Carbenizer, A, 4 C, D, KE.
ist, ,o1 095 07 woo 624 27
ond, 87
rd, " 205
4th, " 208 41 » 38 044 236

6th Run,

Carbenizer, A, B, C. D, E,
ist. .o1 ecw wo gue ood .- Oo
end, " 7.

Sra, " 260
4th, " 200 200 41 eo 3D oo.

It was ericiconally hered tz: analyze all the varisus spec-
imens as we did the ene run in the A cempeund, but en acceunt
ef difficulties and lack ef time we abandened that methed and
analyzed the first and feurth ,01 ef the remaining cemneundg,

The first .°1 in all ef them centains arsund i; carben and
in the feurth .01 it has drepred te between ,30 & ,i0 %, If
the first cemceund is representative ef the rest then there seems
te be a uniferm decrease thrucut the case, and by a micrescepic
examinatien in determining the devnth ef case this was ap-arently
se, the in seme specimens there was a difference ef denth ef
case en epnesite sides ef the specimen, showing that the case
wes net uniferm, tho these cases were few and undsubtedly were

the result <f frulty packing er heating,
meee —
Taking an average ef the carben centents ef the case fer

the different cempeunds ever all the runs they cempare as

fellews;:
B. 1,018 SC,
C, 22090 = E&,
E. 635 ~=6 C~.
A, ooo 7 C¢,
D, 055 7 C,

 
TABLE /# 2,
DEPTH OF CASE,
Runs,
Carbenizer, 1, 27 3, 4, DO 66, Average,

A. 4030 ,043 ~940 , O41 |, § O31 88S
B, wooL 045 041 2045 ,041 040 ~940

C. Ge 047 end0d 46 merers 040 041,

dD, wcor 2044 eck 2049 elao 955 0358

E

, ,07 274) 759 040) © 045,036 ,039

There is such a variation in the abeve table as te depth
ef carbenizatiscn between different runs and difrerent carben-
izers that it is difficult tc pick the carbonizer which gees
the deepest, Tnere is ne fixed rate ef variatien ef depth ef
the carben case, Whatever change dees eccur is undeubtedly
due te furnace conditiens mile the steel was being carben-
ixed, Taking an average ef the depth ef carbenization fer
the different runs, as shevn in the abeve table there is net

much varfaticn, .095 being the greatest,
HEAT CONDUCTIVITY TES

As exnlained en pase 5 ef this thesis these tests were run
and the fellewinc date pnrecured,

An endeaver was mede te held the temperature at 2 cen-
stant value ef 150°) Deg. F, but the average temperature main-
tained was nearer 1529 Deg. F. and when the receptacle centain-
ing the ecrbenizer was first intreduced the temperature ef the
lead bath @rep»yed considerable, The sane weight ef carbenizer

was used in e2ch test,

TABLE ~* 8,
E COMPOUND.
Time, Tztal Minutes, Temperature ef Temperature ef
: Bath F, Carvenicer,

735) 7 15209 162
7334 Z 4510 350
7337 C, 3519 72>
7341 ii, 15°0 880
734% Lode 4.520 1099
7346 15. L557 110°

$007 L°. 15°09 470%
7352 Ty 1550 1289
73:56 aren 15%°7 Lied
830 o. Le 1409
3304 Ot, oC) 14°20
G312 2 1520 1440
0:19 4°, L507 1169
3325 OS, 15°. 1459
33:37 67, £570" 15909
E235 C5 1520 1529
Time

orien oi

td co tO
ew OG) o .O

71

vv
5334

Time

73658

8:00
8:04
83:06
8:03
8:10
L312
8:14
8:16
3220
8:25
8330
83:35
3349
8:44

. Tetal

; Tet-l

-B, COMPOUND,

Minutes,

15909
1499
14590
147%
1459
146%
147%
1420
149%
150%
158)
150"
Lot
15°90
L5Z0
1509
143%
455%
1629
15°90
1500

A, COMPOUND,

Minutes,

Temy,

1

WO
2

z2323323282: 30

ztetews3tst?2232

TABLE

Temp .2f Bath,

Tem-erature cerrectien
oO degrees,

”
ii 4 e

10°
16°
69°
900
&60
369
500
699
700
1900
L109
1°07
1°69
430°
15320
13490
1360
L40%
240:9
1449
2459

TABLE .” 5,

ef Bath,

ii,

Temp, @f Carbsnizer,

Temr. ef Carbenizer,

175
200
480
89°
39C
1099
1160
1°60
4515
1320
14350
1475
150%
L516
1529
TABLE ! 6,

SHRINKAGE TESTS,
Censtant velume 6°27 cu, in, = 1,57 cu, ft,

A wetrhis °7,51" ver cu, ft,

Weight, " shrinkxese Vel, After 7 Shrin, New Comp, Tetal
Run, Befere, After, by weirht, Ca, ft, by vel, Added, Cemn,
1, 9,22 7,45 24,7 220 55,57
2. 11,0 C69 Loy 2 oD Of 3.56
3S. 41,84 19 ,°4 7.0 03D 7.0 2,43
4, 2,44 11.65 G5 204 49 1.50
5, 12,44 Li,cs 6,5 oo 17,5 0623
6, 42,25 625 16,5."

B Cemr-und weighs 21,76 .” er cu, ft.

“3

i. 2,2 627 27

Ze 7 4% Bao Go. .oD LueD 1.75

3. 7.0> GO, 4 ON. one 15.7 200

4, 7,69 wy eo4 28 ° 18,2 94

5S, 7,63 7,46 O.6 ele i .4 .o8

6, 7,65 evo Li) Ser

C Ceup.urd weighs 73,5" ver cu,ft,

3,10 C,1° O70 ond 35,6
10,19 7.0% 25,0 ont OT 4,9
9,53 quod 11,0 00 43,0 1.75

0,06 704 6,5 eat 16.5 1.25
90° e.hD 7,0 ou Jeu »o4

oda Ss OND
e e e e *®

9,56 049 16 , 564

D Cempeund weighs 44,78 ." per cu, ft.

i, 15,2 O88 41,5 on 30,5

2, 17,58 3,56 7h ,0 8 C23 5,2

3, 141,°4 19,05 *,9 eo 15,5 2,25

4, 12,0 12,c9 19.4 000 15,0 1,75

om 11.957 19,59 G,0 229 10,4 250

6, 11,37 263 24 88);
E Cempeund weighs 21.51 "per cu, ft.

@ C+,
a i
‘

wei

Weicht, Shrinkage Bol.after ;-

Run, vefer:, After, by weight, cu, ft, by Vel, Added,

1, 7.56 Uy, 29,9 26 e500

2, © ,09 S04 ao.) »o0 45,6 2,63

3. ° 06 7.05 16,5 vie) 15,8 2,13

4, 5,49 7,75 7,0 2OU 10 .u 200

5, 8.15 a8 1
6.

rink, New Cemp, Tetal

Cenp,

Owing te the fact that the E cempeund was net received until

ene run ef all the ethers had been made and at the end ef the
fifth run «ef A, B, C, & D and the feurth run cf E a werkman

whe was takin, the bexes frem the furnaces accidentally dumped

them, the dats emitted in the abeve tcble: ceuld net be ebtained,

the seme ef the carb:nizer was scsved and 2 sixth run made fcr

cardben cuntent af ca-e,
It is ap arent that from the tables shown ef the carboen-

izing ability ef these varieus cemneunds that there is little

difference so that the cheice ef ens instesd of the ether will
develve unin the cost of the compounds,

Inasmuch as the tet 1 comnmcund used in <nly five runs was

B

ebtained fer the compeund, the fcllevines figures are the

weizcht and velucze ef the new c mreund used of each kind fer

five rung:

TABLE . 7,

A cern, 17.37 = ,655 eu, ft.
:  ] ; 5 "
B 41 e. A 6 045 " e

w aA ” or " t
C LO e 13 ‘ e oy) td e
D LA] 94,20 ” »v04) ‘" \f ,
. ow " a te
ly 15 ° 25 5 eu e
14,

CONCLUSION,

Since the velume ef the carbcnizer used was always kept
censtant threucheut the test, the weights used and the price per
ten will be the determining factors as te “hich will be the
mest eciomeniczl te use, In eur tests, the cin -cund that seemed
te be the best all areund ene te use «as tne B COMPOUND ,

The B COMPOUND weighs less per cu, ft., the least ameunt
ef it was used,and it was the leact dusty cf the five te handle,
It alse g ve a higher vercenteace ef cerbin in the euter case
and cempsriuc well as te derth ef case, [ts cenductivity was net
quite as gsaec but net ensugh aifferent teeffset ‘ts ether ad-

vintages,
 

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