Some Observations On The Lilaticn Cf Casecarhurizefi Steel 811d The Transfcruation koint At 4?COC Ir Zeta Irass Thesis Submitted To The Faculty Of LichigaL State College In Ecrtial fulfillmeni Leecirezents Lcr Truce I/cgree Master Of Science I V ” 11143 E ratchelcr f}. —3/)Jqsl/ June 1932 TfiEE-SIS 93862 The writer wishes to thank lrof. H. E. Euhlcw Lnder whose guidance this work was done, for his many helpful suggestions and kind assistance. Some Observations On The Dilation Cf CRE€“nJ1171 Cc Steel The Ketsllurgist oi today has at his connwnfl Leny more tools to aid him in his search for a more thorough knowl- edgx: of idle 11“.;incc- 1 (Jul clmniical llWDwGltlfBS of imrtels u 68 (I; . A‘ T. 's of 8.JfHC:Y€RrS est). L€Si F‘J than did his 1rodecesso chemical analysis, the principal methods of metellography ere 1hotomicrogrs1hy 9nd thermal analysis. Ihotomicro- graphy reveals the structure of the specimen at ordinery ten1eratures siter it has been subject to chCnical or 1hysical changes. Bring annlicsble only in 'he vicir ity of room temperature, it cannot giro us any iniormation 9s to the reactions to which the metel is subgect during heat treatment. It is common knowledge that metals er1snd on heating and u1on being cooled ccntrsct. U1on lo oking in our h9ndbook at the table of the Coefficients Cf Thermal Ex- pansion, we find a great nutter of materials listed, but only for a stall ranze of ten1er9ture. A great many suc— stences expand at the some rate for several hundred de— grees and then through a small temgereture range expand at an entirely different rate. A thorough knowledge of the e21m_ns ion ch9r9cteris tics of 9 metal throng hout the whole range of tem1erature to which a met9l may be sub- jected is of pr no ir1ortsnce to the man who is endeavor— ing to use the metal to its best 9dvsntsge. We know that steel is composed of several elements. It would be rather surprising if all these elemen s had the same rate of expansion. These elements may ell have a different rate of €11)?HS ion so that the net erpansion -2- would be the average of the algebraic sum of the coef— ficients of all of the constituents. There is a possi— bility that at certain temperatures new compounds or solid solutions may be formed. This would cause the steel to recrys allize and produce marked changes in the dila- tion of the metal. On the other hand, if the dilatometer ( reveals changes in the rate of expansion, even though it is impossible to detect any thermal chanfe, there is evi— dence of a change of state. When a solid material changes from one type of crystal to another, it is always accompanied by an energy change, which ’s generally manifested by an evolution or an absorp— tion of heat. Steel in its various forms is a good example of such a material. Although heat must be conducted into the steel irom an outsi’e source in order to raise its temterature, yet at the instant of recrystallization some of the heat required will te drawn irom the metal itself. This will produce a slight cooling of the metal and conse— quent contraction. Or, if the opposite reaction should occur and heat is evolved during the change, the metal would become warmer, thus causing an increase in the rate of expansion. This phenomenon of absorption and the evolution of heat at certain tem1eratures is known to every one who has had experience in the heat treatment of metals. The temper— atures at which this occurs are commonly called Critical Temperatures. Thermal analysis registers the peculiarities of a metal during its transformation under heat, such as intensity, I CQ I velocity hysteresis and the phenomena of fusion, vaporiza— tion and allotronic transformation in the solid state. The changes that occur in the dilation of a metal are suf- ficiently large so that an instrument can readily be built to detect and record them. There are several excellent in- struments on the market. The instrument usefi in this ex- periment was a Chevenard Industrial Thermal Analyzer. Some Observations Cn The Dilation Of Casecarturized Steel The Chevenard Industrial Thermal Analyzer ised in this investigation is a simple but delicate form of a dilatometer. A picture of his instrument is shown in FigiieUb). The sketch in FigureLZQ shows the instrument with part of the tute cut away to give a view of the specimen and the pyros rod. The specimen, a cylinder of metal 55 millimeters long and 16 millimeters in diameter having an axial hole drilled through it one-fourth inch in diameter, is placed in the silica tube. The specimen is placed firmly against the end of the silica tube which is flat and perpendicular to its axis. A pyros rod(nichle-chromium-tungsten alloy) is placed within the specimen. Two silica rods connect the specimen and the pyros rod through a system of levers to pen arms. Any movement of the specimen is magnified seventy times and is recorded on a revolving drum by the pen arm while the movement of the pyros rod is calibrated to read direct in degrees centigrade. Two curves are drawn on the chart at the same time, one the expansion of the specimen and the other the temperature. Pure charcoal is powdered and placed in the silica tube to keep the specimen from oxidizing, which would in— troduce errors i" the silica tube were eaten away by the iron oxide. The specimen is heated by a horizontal tuhe muffle electric furnace which slides over ‘he silica tube. The current to the furnace is controlled by a finely graded rheostat so that the heating and cooling rates can be con— trolled easily. A small amount of heat may be used while di 9 1'19. i i ———-—-—-.——~«~-.—- -- -. rigure la Figure lb ChE. PCNARD . ‘ -fm—n—a... v - 1 l' 3 Fa- -~ g—;—-‘ 1 .-——_. , ; - -‘ 5.1 ~ » —-vv * - -II._._- _ __ ____- DILA TL ‘Mi 75/? cooling so that any cooling rate down to an air ouench can be obtained. A very fast heating rate can be used by heat- ‘ing up the furnace before it is placed around the silica tube. This instrument is very accurate and measurements made with it checked with those made on a recording interferom- eter. Careful manipulation is necessary in order to produce satisfactory results. As stated before two curves are drawn on the drum. The upper curve is the temperature-time and is ruled off every 50°C. while the lower is the dilation-time curve of the specimen. Many interesting characteristics of metals are shown in the dilation curve which are not shown by any other means of analysis. By the use of the data obtained from the temperature—time and the dilation-time curves, another curve may be plotted using the change in length as on co— ordinate and temperature as the other co—ordinate. As the rate of heating and cooling has a marked effect upon the change in length of the metal, a study of both the dilation- time curves and the dilation-temperature curves should be made in any investigation. Observations On The Dilation 0f Carburized 1020 Steel It is common knowledge that case carburized steel tends to warp and shrink waen heated above the critical temperature. The dilatation of S.A.E. 1020 carburised steel was investigated to find out how long a piece of it would continue to shrink, what depth of case produced the greatest shrinkage, t-e effect of temperature, and heating and cooling rates. Before going into the discussion of this investigation let us see why a piece of carburized steel shrinks when heated through the critical range. Three dilatation curves are shown in Fisure(a). Curve Number 1 shows the dilata— tion of a plain carbon steel, while Number 2 shows the same steel after being carburized. Number 5 shows the curve of a 0.90% carbon steel. All three steels were annealed before being placed in the dilatometer and were cooled at the same rate in the instrument. he curve of the plain low carbon steel has almost a constant rate of expansion until the lower critical is reached. After the recrystallization is complete, the coefficient of expansion again becomes con- stant, but the rate is different from that before the re- crystallization took place. When the metal is cooled, it undergoes the reverse re- action. The metal expands when passing through the critical instead of shrinking as it did when heated through the critical range. At the lower critical, as can be seen from the curve, the metal has expanded almost the same amount as --,* --‘c r v f ’n ‘5.- / / l / '1‘ -m -__._ .~ __.. J—_._fi. 7 . — HENT’HG ---- COOLING [nu/rm” 01 man 5 ,fl ”my . Io" // TEMPEfifiTu‘RE L‘me or zoo‘r it contracted on heatinq. After the metal is cooled below the lower critical, the heating and cooling curves follow each other very closely and then room temperature is reach— ed the metal is practically the same length as before heat- J~ 7 steel that U ing. Curve Number 8 shows the dilatation of a .is almost of the eutectoid composition. The coefficient of expansion is different fron that of plain low carbon steel but on cooling it returns to practically its origi— nal length. As is evident from the curves Number 1 and Number 3, plain low carbon and 0.?0% carbon steels do not s1rinh any 'i T .} (D on being heated through the critical range and that th '3 have different coefficients of expansion. For purposes or (‘3 analysis let us consider ‘he case carburized specinen .s a cylinder of plain low carbon steel surrounded by a ring of eutectcid steel. When the case carburized steel is heated up it continues to expand until the lower critical is reach— ed. At this temperature the case tries to contract but the core is still expending. Then as the temperature continues to rise the case wishes to expand but the core is still changing to gamma iron and prevents the case from eXpanding. After all of the core has changed to gamma iron the piece starts to expand again. The effect of the reactions worlr— C441"- J. ins against each other is l~ss contraction in the carburized k3 1 l L than in the uncarttrize steel. Upon cooling the piece shrinks until the upper critical is reached. The core a this point Legins to expand but at this temperature the case undergoes no reaction so continues to shrink. f the case is fairly think, it will be strong enough to keep the core from expanding the normal amoiit. At ‘he lower critical point he case tries to xpand but the core is holding back and this expansiun is also sur- pressed. Thus it becomes a battle tetween he core and the case and the case seems to get the usper hand, the net effect being a considerable contra tied. The contrac— tion of carburized specimens is consistent. In fact sever” al specimen have been heated up through the critical tem— perature and cooled a great number of times and the con— traction of a single heat, if the heating and cooling rates and the maximum temperature were the same in all cases. Since case-carburized steel, both plain carbon and al- loy, show a contraction on being heated and cooled through _the critical range, a series of tests were run to determine whether contraction would continue to occur on successive heat trea-ments. Before these tests were run, it was de— sirable to know the heating and cooling rate that would produce the maximum temperature and the greatest amount of shrinkage. The dilatation data from the different rates of heating and cooling showed that there was very little dif— ference in the amount of shrinkage that any heating or cooling combination produced. It was therefore decided to use a rapid heat and a rapid cool to save time and also to prevent the specimen from oxidising a great amount which would deteriorate the silica tube. A specimen was heated and cooled rapidly 55 times and shewed only slight oxida- tion and no noticeable decarburization. To determine the temperature that would produce the maximum shrinkage, a rapid heating and cooling rate were used. Since the shrinkage takes place at or above the critical points, the desired temperature must he stove the critical temperature. Temperatures at 500 intervals were tried, above the critical temperature, until 100000 was reached which is the limit of the electric furnace. From the dilatation data it was found tha 95000 and CCGOC .., ( mum and almost identically the sine amount "3 produced the mati of shrinkage. Since 95000 would cause less oxidation, it was used as the maximum temperature to which any Specimen was heated. If a slower rate of heating had been used, the maximum shrinkage might have been produced at a lower temperature. Specimens that have been run in the Dilatometer previ- ous to this had contracted different amounts and seemed to be dependent upon the depth of case. To determine the ef— fect of the depth of case upon the shrinhrge, specimens of S.A.E. 102 steel were carburized for 45 minutes, 2.5 hrs., 5 hrs., 8 hrs., and 12 hours. Each piece was then run in the dilatoueter several times so that the average shrink per heat could be obtained. From the-dilatation data it was found that the shrinkage varies uirec the depth of case. The greater the depth of case, the great— er the shrinkage per heat. There must he a certain depth of case such that the shrinkage will decrease, if a specimen was carburized all the way through, the shrinkage would stop or at least tecome very small. In production or commercial practice, it would follow that in order to get away iron shrinkage and warpage it is best to have as thin a case as possible. -10- After the heating and cooling rates had been determin- ed, a specimen of S.A.E. lOZO steel, carburiaed for 18 hours at l/CC 0}. and cooled in the box, was Ewe ted and cooled through the critical range :l ti es. This specimen shoxed a contr action each time. The shrinkage per heat was not a 001m fit tlut varie with the hee.t in; and cooling rate and also the maximum temperatures reached. The con- traction per each heat is shotn in Table l. The greater amount of contraction shown in hea t lbml ii was caused by the maximum temperature being 1000 higher than in any other heat. Cn the la ast run the temperature was raised to same point as that at which the specimen hat been carburised and then cooled slo.Q through the critical range. The structur‘ of this specimen is shovel in it‘igpure 1.2. This structure may L6 co Iipared with that oi higure S “Ll ch ”‘0 not teen run in the diiat on eter. The structure of the \ 1L8...) -‘ specimens will be dis wets ed on another page. The Rockwell " "I: ‘3 ~ . - 4&1“ V ‘. ‘, ~" . ——, ‘4‘ -:‘ 'II J- ,w‘ -, .V‘I‘u‘ -, .\ a, l— e -. ., J 1. hardnes£;tnr3 the sane Leioie EuALELLer lLJlMJL_-Ww the d .- 4- - ,, -3- _.. m1 V - -, ' ‘i A ”1-“. ." -1‘. .‘ ' - - 4.0 _, , -L I ,, tJJiiwwiebef. _tre overeli.ixnr tn cu. hie specituni'teioie lfiA/ test was 2.l60 inches. After Being shrunk El times the length was only 8.135 inches. This checks the sniinhe;e as measured by the dilatometer. A second specimen ves carburi: ed ior l‘3 hours and heated and cooled H ough the critical range 55 ti es. This specimen, as the “receding one, showed a contraction each heat. The shrinkage per heat also varied as beiore. Table 2 gives the contraction for each heat and the total shrinkage. The cross-sectional area of these spe ecimens chan.§ed verv little, most 0i the IL” contraction taki M1 place lengthwise. This piece contracted Exile l Contraction per Total Shrinloge heat lo. heat in inches in inches 1 0.0C04 0.0004 2 0.0004. 0.0009 3 0.0004 0.0018 4 0.0004 0.0016 P 0.0007 0.0025 6 0.0005 0.00b0 7 0.0006 0.0054 0 0.0006 0.0040 9 0.0006 0.0066 10 0.0007 0.005s 11 0.0010 0.006% 1; 0.0006 0.0069 15 0.0007 0.0076 14 0.0006 0.0082 1F 0.0007 0.0089 16 0.0006 0.0095 17 0.0005 0.0100 18 0.0007 0.0107 19 0.0006 0.0113 20 0.0006 0.0119 21 0.0006 0.0135 .' so much during the 55 heats that the axial hole, in which the gyros rod slides, had to be drilled out tiree tines. Before this specimen was run in the dilatometer, it has wei;hed so that the contraction and the loss in weight could be compared. The loss in \zcight miter the 55 runs was .090 grails wl'-ile the tote. shrinlag was 0.11 from the shrinkage the loss in volume was calculated and there was no relation l:etween loss in weight and shrinkage. Eecause oi the Tact that the contraction filled in 1’]. (T) 011:: CD the hole in which the pyros rod slides, a third sp was made without a hole. After being carburised for 15 ' LA. :01 s it was weighed and run in the dilatoneter 110 times. U , HA This specimen warned a large amount in congarison with the other two. The end of the piece bulged out, the cor— ners rounded off, and it was bent a little lengthwise. The V$L total contractio: of this snecimen is only apgroximately one- ourth great r than the sptcinen th.at we s run 55 times. ”1 oss in weigfli only 0.07 grams which again has no |,_.J C1" '31 g. L0 The relation to the contraction. The amount of contraction per heat does not decrease as the number of runs is increased. 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WM“. ... .oi 7““ .I.\s. ”L’Q\‘ix. N 1,2.» 1.. “to.“ msli . .‘7 . 3.4.Wln. » . “kWhvd‘” 1‘- 4m\Y1~'.‘ .JvérHR—i ‘J 1 of the core. All specimens were heated to 17000“. and cooled at the same rate alter cs rburizinm and alter being run in the dilatometer. Theoretically at least, all of the speci:r.ens should now have the same structure as they were all taken from the same bar of steel. Figure 5 shows a specimen that was heated to lVOOOF. held for 15 minutes and cooled at apprODLimat lv the same reio as were the carburized specimens. The structure is that of normal pearlitic steel. The specimen shown in Fiqure 4 was car- burized ior l2 hours and heated and cooled through the critical range 22 times, Bone 01 the grains of pearlite are about the same size as the original, but most of them are reduced about one-half and look as if they had started to "ball-up." A specimen that was case-ce°burized 12 hours and heated and cooled through the cri tical range 55 times is shown in Figure 5. Although all of the grains of pearlite are reduced in size and appear to have iormed "balls", the original grain boundaries are still visible. Figure 6 is that of a specimen(without an 93519 1 hole drilled through it) which was ca se— calluriaCd Ior 15 hours and heated and cooled through the critical range 110 times. This structure looks like that of Figure 5 except that the pearlite grains are sli :htly larger. Althouch the pearlite grains in Figure 3 and Figure 6 look entirely different, it can be seen from Figure 7 and Figure 8(which were taken respective— ly from the same specimens as weie lig juie 3 and Figure 6) that the grains of pearlite appear very similar at 2000 diameters. The case of the specimen that was heated and F 4" K“ m5 ;'L .. ..I ~ ‘ .m- .... ( \ .31 VI? 5‘ a 3.1 ' ‘ - ~ L) "I 1. ‘ r. "\ ~ 0 ' V '- v . s '9' *- - ' 1- * t. , W‘. 1’? _ 1" I .- . O , \ a ‘( o . f 'l; i I o ' .. ' “ ' .L 0 . D l I‘ I ' “ $ . o v ' ' L - my ‘ ‘ *’ t ' k - ° ' ' 'p 'r ‘X. .L: ‘ v I. I . - w. ‘ro‘Afi I " . o ' "'I z . .4 3v'p1‘F39‘I;L;_ u § ’ 1"" ’ ‘ C o 9 * 1r" ' l . ‘1 -' “:91 3 . ° ‘ ‘._ .‘- Z; i \J » ' ‘fl ‘ J L‘. -. v 4‘ 1 . Y . ,. ' ' v a I . ‘ ‘ -> 4; o -‘ \I 5 .1 . 1 J d' - ) +‘f.v‘ . i “t. ‘ 1 ' v "' ~ 1’ . -“ . . y. t I. J a, -- " I t- . fl. 0 ‘ t 'd . J 5' C 1 \ .fi 4 . V '\ .~" 2 ' n "- ’ 0".“ s f i L. I 2’- I: 1"“. ,' l A I!‘ ' f' v'a " L” '- . “ ‘ ‘ Li ‘.' .l ! -I} ‘ r c ! - I. . Q ' ..‘I ‘ Lb 9 - P: I - l .r. .. r ' . I: V“? ‘W‘ f'gl??? !"w .4‘ . 0 .~ "P; w“ :5 .~ H 9‘ . u'. '4“ ‘1: “S":I2l f1 ‘1 \ .‘ .I‘: . (I t '\~ . If y ‘63 25‘. 0‘)” w y . V {F I. ‘Jk .. H, v ”1‘ ‘ . a v ' .... 0 r '- ' . K i 3 f ‘ 1" ‘ Q. 5'. x ‘ ‘ ( ’t D o 7 1 ' "n- V . ‘ l ‘ ' . . ’4' L" . . ‘ . ’ ,‘ ~ “ \ .‘ .. .o _ ‘ . J § y ‘L 156 .7 S ‘ a '\ )- I. ! ) . . ‘3 ‘0 :11: . . . -. - '. .L‘ ’,‘. . 4‘“ F.) ' ‘0 .' . l ‘ s”\ I J 2 . .' 00’ . ' «u 4", ‘ ; h I) u: i ‘ .9, ‘ 1"»; \ ’ f )- , b ' h . b " ix ‘ I" ’15, " “ 03 "’Q ‘ 1 ' . ‘ ea v x - ‘ . ‘ " c ‘ - ‘& f4. ’ ‘ ., 'N.‘ a. ' 3 ‘g 1' cooled through the critical range 110 times is shown in Figure 9. It can be seen iron this that although the piece was heated and cooled a great number of times, there was practically no decarburization and very little oxidation. Figures 10, ll, 12, and l5 are those of specinens tnot have been case-carburized 45 minutes, 2; hours, 5 notrs, and 8 hours respectively, showing that the grains oi pearlite are reduced in size a small amount after teing heated and cooled through the critical range only twice. In order to determine if heating and cooling the spec- imen through the critical range 110 times had changed the dimensions of the crystal lattice, the following X-"ay patterns were made by Lr. Wayne Sisoin of the University oi Illinois. I. -I" ay S f'zLQ'LIl e S Vle l. :- As recei/ed. Net casecartU‘iyed U) {3.3 B r,» Sample 8. .- Annealed. Not caseoarhurized - Casecerhurized athOCO for 8 hours. Not run in the dilatometer. 'Samnle 5. Samyle 4. :- Casocarburized at 17000 for 15 hours. Run in the dilatometer 110 times. -14- X—Ray Pictures Sample No. 1. la Beam normal to the flat disk samyle. lb - " parallel ” ” " " ” tut ger— pendicular to a radical sectio.. lc ~ Beam parallel to the disk and a radical section. The continuous rings in tie X-Ray patterns ior the tiree sections show that slipgage has taken place in all the grains(Fe crystals) due to the rolling process. The continuous rings of la show that the crystal fragnen f' are arranged at random aroun lb and lo have 6 intensity max'ma on the inside broad band and the 2 inner rings(due to Ka and Kb rays diffracted H; from the llo planes). This shows that the crystal rag- ients have taken up a preferred direction with the llo direction of the body centered lattice parallel to an axis normal to the dish, lut the crystal fragucnts are rotated at random around this direction. Sample No. 4. 2a - X-ray beam normal to the disl. 2b — X—ray beam parallel to the disk. The X-ray patterns of this sample have changed from rings to spots due to the recrystallization of the steel. These Tatterns show that the crystals have grown and are now free from strain and are arranged at random in the 2 directions. oi e'L'I'i . s 'iji _j, i .. 1 ad j' ‘J' .n'k' '~\ 59131719 5 Noticing that there was cor siderable (”iii“- J3 “I _: _ 1 1‘ 1,. ,_ H i_ 1 1 L“. .'._, m f r _ ‘ .Ieienice 411 t e2..ocr3uell.1 a (nice: Iieai isle iihgiae ~aid ifi-e ». , 1 e 01 339 T:35, 87601263 I took two exp S'r s, on Cd v--L ' OuoSl -‘ q- - "‘ 4 r“ ' " .‘ "5 ‘ "J—V“ L‘. fi‘f" " "1"“ 11893" 1,118 4.118188 ._1_£1(. one {183,1 I48 8‘ bSlC-r‘. _LD. to...“ C-,,,€€ 1 I the bear.1\vas normal to Lhe dislc. 5a — Inside 3b - 013.178 1C8. You will notice that there 3 a difference Ietueen tim3:riside :unl the editsiie .Artterisu Theiwg lS ale :1 dif— ferer ce Ietieen the patterns if sample 2 and 3. Eoth as and 8b 59:17 firiications 0: internal strain WIiIe tie dif— J-..' 1 er ence to .een Cs and SI is prob blv due to the c rIurized ‘ ‘ or > ‘7‘ ' ' _.‘ J: \jr. ”‘1‘. .,_ TYI- .5” Irj‘ *_ 1-: Snglc 4 ul.ec;._,t:;13 were taken .LIUI“ no. 4 l. C 5-H“: ‘ 8 L": {J I H 1'? rd C] [..J. C ‘1 4-D - Outside. There {2.1117ears to to only a slight é:_ii'iei‘-c11ce INGI‘JI€‘"'11 L" 17 ' -'- J ‘v . 7~.T~ 'T’ . 1 1 JCA~eL.-1 f..:/r T294 L.’ L' Cir-1.1.1.8 OJ- 3:3-‘1-1131 C Li 3.1, o L,‘ fillLL {1. g .L ’1- I“ . ' ”2"." — —,- . a. . — J- " "" "J a . . " fl .1 .. L :3 ‘\ lfctea Tlfxtliiicrwnice 711(L18317her Lu. ULC 1111 s Li'-7b ELK 4L " - 4.1. -.. ' -. .- .. ..n ._ J.- .. t‘ ' .... r‘ ,. u“- , . are due to the iln being a greater cistanCc iron tn; speCimen. ‘4‘ h ' » . r —~. .. J.~ - a Tlie :IIIIVEJ vatigeiuis IICl.€ t.£ e. UL. si.on. .iie tine oi ‘ '1 "v" J~1'~‘7~ 4-” V A)- 4- r7. - ~, 0‘” '21. ' I“ J “'1 3 tin: €1wr. s ;.i.ihui tin: sax. le. IIi 01%-er on tryter.unie 3“- Lil. -,. _ .2 , , 1. . - - .1. 4-1- A ' J. ‘ r- ("1 -' ' ~- m treatment of hasslng through .he Iricical rante l0. timés ..r. . -"~ 7'3 «h. x. 1 : /-'{' ""‘ f I” Ljilry'L’ J 11831 (£135; cit tl.c (ill.811&lx CE; e- t} e :lrcui l-a ice ,1c.mfl- .LC , . .... i f, ' . ‘-;‘I r 1 -. _ r '1‘ 'J .L .9. -_ T-rfi ~.- _~ determinations o; the enrol.“ ch- inc crystii lettiCe “LlC vC- (7:171 "‘ a" “ma 1L) . — ..r. +1 "1 of ‘ R _ _L 1 ‘. ‘ f“ _.-. _o -. Tiff \1".W~,rz‘ . -] '11 r- 1-; LC). r) C ‘ :-L I. _~ (_ . . egée EIIOVMI (Mi IWME~ lcnt‘ I wl..:s Id Ckaus . ~—{) » . I I x 3'12} ,‘L‘ 1 J.'!. . Li¢-U L; (31' _‘J J_ I C- t, J. .... .L J_ MCI U . ‘31’ (N _ x >._) o o 7 1 Ju‘n ’-L» 1 w .. ‘ x 'l -f 4" .5... O 5 J4 been from O 3." 11'] on UV gl (0 . Olen) 1".“‘4' ine if 'e:e CJUrd li ”s xmrc Jr- ibon from 113 e UT‘Uir n7, .etof‘ :1flxee e35 nge ;n*¢7€_:: oi 5:: ;le ; i‘ *” 311?:‘6136 oif 17s. I? :fl-"'s L; e e vLieL iKLiCui : J‘efi ”1'7 “f?' {U reiiee rle' Liai 21h iron 3.:( “r 1-57/c. *Z;e :‘.:e uI‘iI7t tFU'e7‘CC’ .Z;e LC \ I O O of solid .0. J .1. 0 Ti" r3116: '__M.-— .L. f. -3 -‘ ."‘ L/ ‘J .. L'_(/ I: 1 Le Similar ”TIC. ALI: SE; Tile X- re y Im- tte ern ding a small 10 E L _L. b -16.. 031 i 1 110 solUtion u 77 A. :llfllOlC XTWIte Cu T‘el‘ififiie to the zgic line, WU eee ?1%: elnr'i‘ Ge:””‘e 1 3‘1? file i“ a e Liwn C d peeeiIle sli IL etiit if A 'tr*'e*“ s ifixe :zeiw; lixze. 2T:U_xtill. u A I o .. q (if '1‘: I 1'.“ I" I' .e- \‘ ‘. _ 1 i mi VICUiLi '3:' Clfllolfi3l(fll long films W 8 1‘11 .7- _L 4. F} T}- \‘lJ 1*, ‘1 o 1 l S (3 LS SEC. W'i .‘r 8 (N L) -h.’-,‘ Letal irogre. .{1 -‘~.— (‘ rv 'L.‘ obte '1’. (TI lee * - l.) , I . c?» 7 e Q ~ ..'_ _ L K/ 1 pi" J 7 l _1 \J g ‘7 f“'”" r _. A. '~,'-L ~ ‘ w J C. A. . _ \i 1-. N Y “W 'x » (:3 DJ v \I I“? f' ‘ Li 0 .L .'. .~. —1 4, >I ___~ .5 .J A, .J.‘ '. k. . .‘ .1 " - .. w {H ‘ -‘ o . ‘" ) r Cl. I—Jl A }. 1;;151 . 'i A I ‘ ' I ‘ \1} l l L. 1:) o l1’18d thin V H-. r“ .,— a ‘fi . I. 1 ‘7 _ ., ‘ b ‘ v a”. 1 ~ 1_ ... a JV r J1. 4— ilwx: tie i.ore gflJg‘ mowJ: 1L61(; is 21 §OSEqullltjg Ulfitu a few conclusions mvy be Craun. lirst:— Css—cartrrized steel with a thin case will have less ‘I tenfiency to warp than steel with a trick case. Secondz- Cssecnrtr‘ized steel if slowly coclefi frog the car- J t4 burizinf heat enfi then Lardenei by cuenching from just above the lower critical will have the least tencency to warp or shrink Cue to the fact that we get awry from the tcnfiency of the core and case to work against each other. Third;- Casecsrturized steel shrinks every time it is heated and cooled through the critical. Fiurthz- Repeated shrinks have very little ii any effect up- on the sgsce lattice. The Transiormation Point At 47000 In Beta Brass The late Sir Roberts-Austen in 1697 published the first complete freezi15 noint curve of the copger—zinc alloys. Fl In his d'o rem, which is shown in Figure l certain thermal 9 x; 1: K”; *3 1. a 1 T .chsngcs regresented tv horizontal lines b3, 00, en, end i e' were included. As *sn be seen from his diagram, these horizontal lines were interpreted by him as evidence of the presence or eutectics at these temperatures. This diagram was the iirst attempt to construct what would in present day ptrsseology be called the equilibrium diagram of the cogper-zinc system. The horizontal line e"e‘ indicates a thermal change at about 47000. occurring in alloys containing approximate- ly 46 to 76% of copper. Although Roberts-Austen regarded e“e' as evidence of a eutectic change, he did not find any v supgcrt ior this View in his study of the structures of the alloys in this range and he does not appear to have thought or any other interpretation of this thernsl change. At a letter date E. S. Sheterd made a careful determi— nation of the constitution oi this series oi alloys, end in 1904 published the first conglete equilibrium diagram of the Isten. This diagram is regroeuccd in figure 2. o o (D “f I [W Fl 5 o ,3 1 E. S. Sheperd mane repeated records oi the leqting and cool- r ,4 I $79 ing curves of alloys ranging in conyosition iron [O to conger without finding any evidence oi the line e"e'. ..a t!» 9 MO»: (NRQNQ‘ .3 . .. be e. a. c I ...-til; .lllll 1‘ a. 99 .Qm yr: 4. list: .1 s3. «brow. - . I--- . , ,. 2:. Q L. ...c - Jun-h— l P 5. «~99 . u it .4 QB: K. a. .~ Alum §¥§u NQRbfiflbfifii a. a. a Q §%. Q% as §§h "D 89§§N Q9» $8 QQK 8% Ox - - _— *- 4"..- .. r!- —.--—~ 8% “use. 8 .3 QNRKQQ NQVR kwbukmnx -2— Teiel also ecis -.L‘.L1.e 8‘1 line e'*e' was real or not. v--. - r‘s‘ ' 1 1/: oL—q- W. 1 /‘-" ' existence, and concltled, UHULLQ u r)“ 13.: C111 2341 q ”11,—: "_ l-‘l 1nd hlwsiws --§.} , were able to rediscover hoter e"e' and prove its existence. agree exactly ith those 4- n . ‘J tezneri ure st wii h in both cases. It his teen shown hy Shencrd end loys cnnrtsininf;gflgnrt rlUs twaww h sijruc id; 06011”? in_tf e :flnience: 0i nzst to due to the bets consui1 Lent :Fe : ysic l interjrctotioq oi this situtes in olteroli-i in She“er7‘s 'i tre two curv s blbr 8H“ Cic‘ _ _ _L. (4 '11 m _’_\. _. /,~A. m J‘. - J‘— A- r- 1 wuf A Le LL a u ‘,. /\J u . , [13.6.11 tile 7.1. -j‘rSlUC‘J. _., .'. ., -1. .._.. ‘1 ‘1 1, A J ‘ , .1 1‘ -1, _: ,_ J-Jlrl U ‘uLJUltI L H [ii-.5. U bl ELL 9 .L ._, ml 1.1 A ,. L z -3- . ., 4 .J 4.’;,.-, .. r. ..., l Ulla L..L L]. C41 ’o- "L k l. C c CT .4‘5‘93 ‘ L1-L e , «r 11M. .1- T“ I‘\ .2 fl. ".-l“? [JO .. ‘.'\J(L_L—|_b’ -1 47000. there Re} C to normal tete _ ,qfi .--dl - n! V .n '1 , ‘ . ... 8.]501314uliuilc : \_i. kl the Hutu; Ckfil 637:7 usinf ‘...14 end ”litl .AliflLOLLi l S J,1, ”4-6/3 -' J- _L L; fl 1’1 "b rAustxni's A evidrnice ~ L I Cl new -1. .L‘ .- 11ch LI)..€.L1 '1’“. " ”r"! .1. ‘LJ _.. si to ti 711 1;}: l errOJ diiferen“isl n .,,_- . -.1- noiizcatsl Julie 1.1....j. LS s-Austen's 7 | I‘ " "' CiL‘;7,1i}_ Q :ent 5, .1- .~ LC U 1 -1.-. 'T .1. n (x 1—"A-Ls/U (4 described -1- 1 L- _- 1e teunersttre lnClCTQ a "1 no -r- Oi. r“ (‘14- J CCUrs 0‘” its ‘- FN- ‘L ‘ “‘ 1‘ t \ J —i J- ’ _— " 11C) '1€ C)", r; ESL) (‘ full? (3.- —~‘! igi-e 4.1.0 .LLU Urn ‘_\.— lill€ e U- CO ed tectics 1" C.‘ .'... LJ (1 C '4‘ 1“ r .— .>__. U I ,. r“. W \..' ”I“- . Atove t e 1"; 36 '14 r ..L , Jr “'3 ; 0;. hill 6 [ll 11 as“. WE“. Ill: ..v. N» w - _ 4 m l i _ l H k.‘ , l ; / / _ NNKKQQ kagxwukwk According to ligure 2, E is s hinoyeneeus solid solu— tion which miy vary in composition at 47000. from to 51.0% copperu In this case the composition of the ought to influence the temperature of the critical for the following r esons. Alloys to the leit of the point X figure 3 on coolina from temperetures above the line hlx deposit alpha at temperatures on that line. The separation of alpha proceeds with Telling temperatures, and beta is consecuently impoverished in copper until at A7000. the composition is represented by the point X. Alloys to the right of y when cooled from above the line cly deposit fauna, which means that sets hecomes relatively richer in copper until at 4700C. its composi— tion corresponds to the point y. In these two classes of alloys, if the two lines hlx end cly do not meet, the compositiois of tets at 47000 would be quite differ— ent, and if the critical point were due to an allotropic change, the temperature at which it occurred should he different in the two classes, that is, alpha plus bets and beta plus reuse. Since the critical point indicated on the disg'am in Figure 3 occurs at the same temperature in both the alpha plus beta and the bets plus gamma alloys, Carpenter and Edwards discredited the foregoing diagram and tried to find evidence to support what appeared to them to he the only alternative explanation. Carpenter and Edwards' hypothesis is that the solubility lines b1b4 and 9193 actually meet at a point at 47000 end at this temperature 5'- 2, '9’- ;3’ the followirg inversion occurs B" 6% Q0. 8‘ Q5... Vu .. .. ”an, A So. dill L i g .- , . A”... . 68‘ .-i’llltu‘ I?!» n r , ‘14 Qfix. QNQQQQ NQSQSNQQMK e 9“. 9w OK 6%. a 8‘ §§h Q3. __ _- , if ._l'. Quw 8k I .\V$§/ , 7‘40 To, .,;1 . -.-wi --o. 'LpJ " l fi-1. _- ~ ills...) _‘ _U a; L “1;: \ Ulel -JCC‘ LEI. t: LC Kurt e" LLJ .1, Ll'lL: ,‘:r\,i .~ ‘ lb!L \‘ ‘x d '1‘ l '1 _1 -"e A Q ~ 1‘ ; ~1 ‘ r—‘ (I '~ ( ‘-.y P} _‘ >\ — I“ J- J |.4&-‘ n J. .... - .«L _t— ..L O .L- _ s. -_- i t»— |;; l- '7 t! ,' 3”,“... (J m L.“ K- kl A \, L L, 9 b J. 1:. J ,-,~‘r‘i(‘,f“ 4], "1-4. - '1 1 _J a , a '3 " ‘t .‘ 2‘ ‘4 ’ z:\.JKI-, ti_e J: Jo l-o’ e 1 :1 l_t Litesi '-l ' _ 1‘ tr 1:11 1» ‘1 .. we r'w + \ , Mn 1—“ \ ---3 w, +1» , c." - - - J ~' -- i - i _ 7. . - t . _ ' "r r \ , .. ' ' - “ " .- -- ' P 0‘ if--.) p E, i. 5“ ‘ kw; C "I __ ,‘..... 1.4-K; .. (-34... T... ‘, U1. ‘ ..i, I- .4- 27.1. -- _L 1 _- L I) . ._ - m .. V“. l- “..., . . ' ”I Jul . 7- ‘ _... f . or lCCt sixth.“ Cl C“; 'l'ln.€7”LllH lzs€ Praia o4..,.uu .. 4.1-‘u-~g.u j 1 W‘ OH’; :‘r' r n r-' ~ 1“ ""1 . 'Y"'Y Hem ~ ’ P e ' w J- L 4 c,._i-C_ 6.3.. A.l ‘. .L L ilk L- Ll C. ' " L: - i ' C cf .C .43; k‘ w . .L’C “11C Cil . x 7! .. r- -- - r; n 1 —5-'~r‘ . A£"‘"v ‘y -‘- ’ *1 1‘1 " r J r, ’\‘ '1‘ r J- ~' J ' “ _,_7 - *1 ‘ '1‘- "...L»~ t I. d 19.x. ' C‘ -' t -_l L.) J ... .1. ,. El |J_3‘€] 1.7 CA .4 'C“ ..- Ct: LL 2, - "_ .L. .‘ . l. ' J_ . V , ‘ ’ {"T‘. r L“ ' __ . _. 1 'T ' r‘ n ‘ ' - .. (”fr-‘1 17W“ 1. rr_‘ ",1 ‘ 1" - " _ ,' l 4 r. --"*T V r» l;.(-. l 16 Kalil LC k".2,..--'..g;‘.’, 0.1.37 UL:.,_‘_S o .LllC u-t {I CUJUJ Ll -:‘._L-_'\:_,’ _..-H + -,J._—., rw-_ - .1, cw.“ heave crr :l~ r llilil is; si_c1u: ill i:u,La7e 1 ‘__ _._ _. ., ‘.:,,1W....,-, ‘. V ., :~ . EiLlCfl' 014.’€W s i.rc“ t} is l»f lteiird ilulcpgiseanie -«U to. _-lipoill lo * I it 1* o rust {anal ~”strut. Lu tut .l - 11;: :1t 43,C’3C. j‘ci‘ .¢ “xiii s :»s sliozai is: lligfrufe :’. i J‘-i t}_e stove otnte_rnt it is eviient lnbt the cl 1 t (J constit — F r“ ti? Fcuilitriu? fis— .: n , A . .. 1 _, _1 -, ,L \‘ ,.—« ., J, _L' :' ~. ‘ , tl’l reoLireo ,5 lLC inteipictatio oi l.. ,i ‘“““cult to detect structur— (“N F‘.’ r) I“! ,_; 5—" :3 Lu; 9 A c‘ H (—+ r‘." (U <1" \i‘ '4 l 1-“ }- L "D F! A ‘1 ‘—-.J ( 1 Q J ‘1 t? (D '3) . J L) U] ,'\ \J l F'U T?“ ”J I (D H >- 1 [_J- ‘3 ’ J 0 re 0 O O -1 1‘ - W .. A. -.- . x . ‘1". \H ' I“ C". .‘ Carpenter an: nduards h€l€ LnaLle to SLCJ in fNE 30:1091 I . (u, - __ __ . -, _1. -‘ ta on eineelins below 47C C interted lfltO alpha (D IE‘IHIEI' thr t 1 ' 1 ' . '4"? § 7 uiuc {nhp0. They ran leetirs one coolinfl cu} 95 CH alpha J. —o— -3.) ._v. .A‘ .Lng v- -. - r—‘a , . U 'alll C‘ {1.1. l ”N Plus beta, beta and beta plus 1470 and the third 7 - ' - ° - rv‘ t” "- J ': alleys “ore the critical tenpeiaUUIes a t' . <3 r'l at 45700. It can he se~i iE' on tre ground of constancy e; ~gw; established. Since the a pha pl lL N .19 went i . . .0 J‘ . 2 ...a ‘ \ e ..I \ . ...t ewwwfi . h A .. h a. 9.. . ‘ ‘ .%¢ n. Y .1» A 4 J 1 .. 1- Kl i ,...'? {h ‘Luq - \ " ‘le~_,_\)__Ii ‘1; 4Li 6 :14. E“ TC ;_L»(.: ‘L— C~ »r“—- ~* 06 - , i . .. A .. 41‘ . ' ' _ .1. ., - i, ,1 ~~ .- , . ,1 1‘ ~-..' A _ long rnneels ”elot 'lfi CrlthHl temperattie -x 1:“ LELELE ' “ 1.‘ ‘.. -'fi I“ v ’V' J‘I‘ VF. “ . ' . .ot 091 cu -LZLchm 0« le 11“ L.cate) 0 r“ C 3 1—1 a-< I :1 J k- C -) A 4.1 A . -:- - 31" .. 1,1, --:J. J- ., it, . ~,~. .. .1—.— .- ‘3: .v r“ Lotes:e 1_ec:ts \.cl-LH IU40tiJSJ.L3ch .le <11:;,_rei Egtlefl 341 i-lngre z. ('1‘ . '7‘ . r‘c" . w ‘r‘f‘ I " . _, ‘ '0 ’1 ‘ ' 1 ' ‘1‘ ' l V‘ J ‘ ('I iigLs (gLoLisug 11-101- 15::rc1n_orxxr . _- L; Lie: l€1AD (C itio .0 .1»- vi; 1. ~--. " W, " ... ,1 . . fr It- -.. oi Lhe u. ignel “rtal: nrnalool, lee lean essemlloa ire“ data calciLli" selected from a great neny SZLI cee. It is '33 ssi le here to udle Beteiled enfi edeouate eclnowlefig— Ixeniri oi"the TLCRL' iniaistigfiinciwg ccnrtrilwgiiru' to 't litriru diarrem. It will be seifi here, however, that tee ,rrnsforxotior, exteniing iron 4730C tn £7CCC irom tie elgha to the {euro solrtility curves, its been tilen fro: tne onto Ci Laughton enfl Griffiths. A double lino exteniinf through the beta field represents 9 narrow E plus F' field. According to the phase rule tLis could not le 3 single line sin ce t solid wolut;ons cen— J 1 not exist rLrt to each 0. or. As has been state& before, long anneals telow tne - - _: . . .L «-_. f‘ - ' . -0 ‘.: , .1- ,1. .. ...: 011 L109]. t€ghfifiF3L14(3 01 lmrta truiss it :lefl. to ELMLI sigins oi recrvstsllivotion e: cept foseilly a slight grain growth. OSSible to trevent the B to B’ ’0 LJ. r ,1 w -1 , gistshne.ergws that in l_? epeated nuoncfics H tronniornetivn by ordinarv ore noning. from VECOC into ice cold brine of beta brass £21195 +n re— {0 veal a H itient structure than that of nne en_leo Lets lrpss. The only noticenlle Ciiference was that the repeated cuencb— es creole? the syecimen at the (rein boundeiies. It hes been found hr l-rey analysis that there is no iifference in \‘OO -IOOO UGIJSBlIEKJ-runanaduqu O O Q C) C) F. * bfiO O o a r T ‘_’ "* (poppy r-—---------—1 (3.0.1 ‘. __.___ __.._ J9 . " ‘ - “a Figure 7". ”we—~— h "' o r "--— Q 3 : $ '1 , C; 1 " A". 5'} "‘ o . , f H,_.__J:_4.3 _ t " . Jo O I ? 0 --- “ z 1 1 ...-s n .0. at C I l N M .J 7. f f ,_ n m r- 0 r. .- D -9 2 1:9 3- a» (J 10 D .l '0 II. 9". on D 0o .50..) ,0 n oturot a 00 L7. k .k. .255 9:03 9 o. o :~ ~: N:— W m~uNmal a bx Ox R. 0 I g A..- _ + .--—..iA—v v.‘ Percem - Bq quhfi LLquLd Brass ' ‘—‘T‘"_"”' T - _..—1 l \\ 905 __ “W I W Beta { '( 190’ __ '3‘ e b ‘—‘ I Gamma or ‘1’ 15 25 I 535 ,B‘fl 470' ‘1’ 453' h r I , V aup’ ,5 19‘7” g, 1 70 60 10 40 30 30 4O 50 60 70 -6- the specs lattice letween annealed and onenched bets l:rvss. 1 from tne above data it is evident tlet at the grcsent it is inyossitle to diiieieqtinir Tet .een B end L'. Hefner trot it iorrerd evidence to show that L could he foruee svn— 4— .0 w -!_ | ._4 -,_ V ‘1” ,— . ' A <. ‘_~ _I 1‘ ' theticsljwrsat ten ereiie az'telow rt;t¢oxni Lie trervu