CURRENT EVENTS

A L L - U N I O N S C I E N T I F I C - T E C H N I C A L CONFERENCE ON MODERN

OF HEAT T R E A T M E N T OF M A C H I N E PARTS AND TOOLS

E. A. U l ' y a n i n

Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 10, pp. 60-64, October, 1964

METHODS

The annual All-Union Scientific-Technical Conference on Modern Methods of Heat Treatment of Machine Parts and Tools was held in Volgograd, May 26-28.

A. A. Shmykov, president of the organization committee, opened the conference with a summary of the work done as the result of the decisions made at the last conference and briefly described the present state of the theory and practice of heat treatment.

The first plenary meeting was devoted to reports concerning the Iatest achievements in metal science, physics of metals, and the theory of heat treatment.

G. V. Kurdyumov and R. I. ~ntin (Central Scientific Research Institute of Ferrous Metallurgy) presented a re- view of the tendencies and developments of theoretical metal science.

The speakers noted the close relationship between modern metal science and the electron themy of metals, thermodynamics, kinetics of transformation, and crystal lattice defects. At the present time the development of a theoretical science of metals is characterized by the replacement of the description of various phenomena by studies of their internal mechanisms.

In recent years investigations of phase transformations have been characterized by the use of thermodynamic and kinetic factors, peculiarities of transformations in the solid state, and the mobility of the atoms of the matrix. Some important results of investigations concerning martensitic transformations, aging of alloys, and the effect of high pressures on the equilibrium and kinetics of transformations were briefly discussed. It was noted that in princi- ple it is possible to obtain new structures in alloys under high pressure.

Rapid cooling of pure metals from high temperatures stabilizes a high concentration of vacancies. The me- chanical properties of metals change as the result of quenching followed by aging even in the absence of poly- morphie transformations. Similar changes occur as the result of neutron bombardment followed by aging.

One of the most important effects of real structures on the processes occurring in metals is the nonuniform diffusion through and along the boundaries of grains.

Studies of plastic deformation, of the destruction of metals, and of imperfections of the crystat structure (dis- locations, vacancies, stacking defects, etc.) have increased rapidly. Investigations of the physical nature of harden- ing, softening, and cold brittleness in metals have been made on the basis of the results of these studies.

The investigations deal with general structural singularities of the high strength state of metals resulting from quenching, plastic deformation, and thermomechanical treatment of steels, and aging of martensite. Some of the important factors responsible for the heat resistance of alloys have been determined.

In conclusion, the authors noted the most important problems of theoretical metal science concerning the strength and ductility of alloys.

F. N. Tavadze and his collaborators (I. A. Bairamishvili, V. Sh. Metreveli, L. G. Sakvarelidze, N. A.Zoidze, O. V. Tsagareishvili, and A. G. Mikeladze) (Gruzinskii Institute of Metallurgy); N. N. Lipchin (Perm' Polytechnical Institute); L. A. Metashop (All-Union Correspondance Institute of Machine Construction); and M.R. Gedberg (Volgo- grad Polytechnical Institute) gave reports on different problems of theoretical metal science.

They discussed some aspects of the dislocation structure of metals and also the effect of excess phases on the properties of steel.

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After the reports concerning theoretical me~al science the section meetings began.

S e c t i o n on the R o l e and M e a n i n g of H e a t T r e a t m e n t and C h e m i c o t h e r m a l T r e a t m e n t "in I m p r o v i n g t h e M e c h a n i c a l P r o p e r t i e s o f S t e e l s .

P, O. Pashkov (Volgograd Polytechnical Institute) reported on modern theoretical concepts of strength and embrittlement of metals and pointed out the problems which must be solved by metal scientists to increase the quality of steels and alloys. A considerable part of his talk concerned the description of methods of creating ma- terials and structures with high strength: the use of dislocation-free single crystals and polycrystals (whiskers), metallic precipitates or condensed films, and bimetallic and multilayered articles. He also described new types of treatment: thermomechanical treatment, strengthening by explosion, partial strengthening, and the use of forging and rolling heat in heat treatments.

The reporter noted that heat treatment of low carbon and alloyed steels is not used enough at the present time.

I. L. Mirkin, G. L. Kusht, and Z. N. Petropavlovskii (Central Scientific Research Institute of Machine Con- struction) presented data on the comparison of the characteristic temperature and the resistance of iron attoys to relaxation. They showed that the heat resistance of alloys is determined to a great extent by the strength of the interatomic bonds in the crystal lattice.

Reports concerning particular cases of the effect of heat treatment on the properties of steel were of particular interest. These reports were: "Effect of heat treatment on the mechanical properties of 36G2S steel," K. I. Antipov and V. K. Shashkova (Volgograd Krasnyi Oktyabr' Plant); "Effect of heating at subcritical temperatures on the ductiiity ofsteelNo. 45 during normalization," by K. K. Kozlov (Volgograd Krasnyi Oktyabr' Plant); "Mechanical properties of case hardened steel used for highly stressed gears after different heat treatment methods in hot media," by M. A. Baiter, V. N. Muzhikova, and T. V. Filichkina (Tractor Machine Construction Plant, Khar'kov).

M. G. Lozinskii and A. N. Romanov (Institute of Machine Studies, Moscow) reported on a new method of studying the microstructural peculiarities of the development of ruptures resulting from fatigue tests a high temper-

atures and alternating bending.

S e c t i o n on T e c h n o l o g y of H e a t T r e a t . m e n t . . . . . . . . . . . of S t e e l and Use of M o d e r n P r o c e s s e s

in I n d u s t r y A. D. Assonov (Moscow Evening Metallurgical Institute) presented the introductory review lecture, where he

described the general development of the technology of heat treatment of machine parts and tools.

Reports on some problems of the practice of heat treatment and the properties of structural materials were presented. P. A. Suvernev talked on the "Application of modern methods of heat treatment at the Gor'kii Auto- mobile Plant." Ya. R. Rauzin, A. V. Velikanov, E. A. Shut, and Yu. M. Parvishev (Central Scientific Institute of MPS) reported on ~High carbon steels and their heat treatment." I, V. Paisov, G. I. Kreimerman, and V. S. Tomsin- skii (Moscow Institute of Steels and Alloys) reported on ~High strength structural steels." E. A. Smol'nikov (VNII) reported on "Decarburization during heating of steel articles in molten salts. ~ V.N. Biryukova (Gor'kii Metal- lurgical Piano reported on "Isothermal quenching of tool steels." V. G. Zhoga, V. D. Dneprovskii (VNIITMASh, Volgograd) reported on the "Use of automated furnaces for heat treatment of forged parts at the Volgograd Tractor Plant." N. S. Neshenko (New Kramatorsk Machine Plant, Kramatorsk) reported on "Accelerated heat treatment of

parts up to 1500 mm in diameter. ~

S e c t i o n on T h e r m o m e c h a n i c a l T r e a t m e n t and I t s A p p l i c a t i o n s in I n d u s t r y . The review of "Thermomechanical and thermomagnetic treatment" by M. L. Bernshtein (Moscow Institute

of Steels and Alloys) was presented as a written report because of the author's illness.

In this report thermomechanical treatment was defined as deformation, heating, and cooling operations in which the structure of metals and alloys, and therefore their properties, are determined by the high density and distribution of structural imperfections created by cold working.

According to this author, the singularities of the structure after thermomechanical treatment are small grains, crystallographic deformation texture, dislocation texture, and precipitation texture.

High temperature thermomechanical treatment (cold working above the Ac~ point) and low temperature therm- omechanical treatment (intermediate cold working temperatures) are characterized by the following: Low temper i

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ature thermomechanical treatment renders the material very strong; high temperature thermomechanical treatment leads to a lower strength but a higher ductility. Simultaneous thermomechanical t reatment and a magnetic field induce additional improvement of the properties.

Thermomechanical treatment of refractory austenitic steels is of great interest. Thermomechanica l treat- rnent accelerates aging and renders the distribution of strengthening phases more uniform in these steels.

Thermomechanical treatment of titanium, titanium alloys, and molybdenum are very promising. High tem- perature thermomechanical treatment induces polygonization, increase of resistance to small plastic deformation, and decrease of cold brittleness temperatures in these metals.

M. E. B lanter (All-Union Correspondance Machine Construction Institute) presented a review of the modem state of tt~ermomechanical treatment and of other methods of producing superstrong materials resulting from de- formation of the structure during short heating periods. This author reviewed the advantages and disadvantages of high and low temperature thermomechanical treatment, of thermomagnetic treatment, and of electron pulse treat- ment of metals.

He described the effect of temperature and degree of plastic deformation during compression on the properties of 40KhNMA steel. The optimum combination of strength, ductility, and impact strength results from thermome- chanical treatment at 700-850~ and high degrees of deformation. Thermomechanical treatment fragments the grains and blocks and increases the second-order stresses and the dislocation density. The last two factors determine the values of the ultimate strength and yield strength of the s tee l Processes of partial recrystallization occurring during high temperature thermomeehanicat treatment to increase the ductili ty of the steel are of great interest.

R. I. Shukyurov and t. V. Paisov (Moscow Institute of Steels and Alloys) reported on the effect of high temper- ature thermomechanical treatment on the properties of 55S2 spring steel alloyed with chromium, molybdenum, tungsten, and vanadium. They noted the favorable effect of high temperature thermomechanical treatment on the mechanical properties of the steel in the case of low and medium degrees of swaging (up to 50%). Additional alloying with these elements decreases the recrystallization rate. High temperature thermomechanical treatment is useful for large machine parts.

A. P. Gulyaev (Central Scientific Research Institute of Ferrous Metallurgy) and M. L. Kashnikova (Central Scientific Research Institute of Machine Construction) discussed the effect of plastic deformation on the decomposi- tion of austenite. These authors showed that the ~inheritance ~ of cold working has no effect on the transformation of austenite.

All these reports were discussed,

F. L. Lokshin and A. P. Derevyannykh indicated that the application of impact thermomechanical treatment in liquids decreases the susceptibility to quenching cracks

S e c t i o n on M e t a l S c i e n c e and H e a t T r e a t m e n t o f A l l o y s f o r C h e m i c a I M a c h i n e C o n s t r u c t i o n

A review of HMetals and alloys in chemical machine construction n was presented by A. L. Belinkii, M. B. Sha- piro, G. L. Shvarts, and M. M. Kristal' (Scientific Research lnsitute of Chemical Machine Construction). The re- ports concerned the properties, the heat treatment, and the areas of applicability of the mose widely used stainless steels of the austenitic, ferritic, and austenitic-ferritic types.

Titanium appears to be a promising metal for chemical machine construction because of its high corrosion resistance and high strength. Titanium can be used in place of nickel alloys and highly alloyed steels in highly aggressive media. The authors discussed the corrosion resistance of nickel and its alloys (of the Hastelloy type).

One effective method of saving scarce corrosion resistant materials is the use of bimetals. The authors described different types of two-layer sheets produced domestically. They noted that high quality bimetals have not yet been widely used.

T. A. Zhadan (Central Scientific Insitute of Ferrous Metallurgy) reported on a new stainless steel, OKhI8G8N2T, containing a small amount of nickel which is used in equipment for the preparation of nitric acid (up to 50%).

M. N. Kul'kova and A. P. Okenko (Volgograd Krasnyi Oktyabr' Plant) discussed the causes of embrittlement of Kh21NST and Kh25T steels. The authors indicated the methods of eliminating.this defect.

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K. E. Miroshnikova (MIKhM) reported on the susceptibility of ~I943, EP213, and ~I711 steels to intercrystalline

corrosion.

The personnel of VNIITMASh and the Krasnyi Oktyabr' Plant, M. P. Sidel'kovskii, Tyurin, S. N. Prantsuzov, V. I. Danilin, K. I. Antipov, O. F. Frolov, and B. S. Petrov, presented a large amount of data on the effect of boron on the properties of 23N18 and KhlSN10T stainless steels. Microadditions of boron to 23N18 steel increase its ductility at high temperatures substantially and improve its resistance to high temperature.

The addition of microscopic amounts of boron to KhlSN10T steel decreases its susceptibility to intercrystal- line corrosion, which decreases the expenditure of the metal.

The authors also investigated the effect of rare earth elements on the properties of Khl8N10T steel. It was found that the rare earth elements have the same effect as boron, although this effect is somewhat less.

Yu. S. Medvedev (GIPRONeftemash) reported on a new austenitic stainless steel, OKhlTG8N5AM2, which has high resistance to intercrystalline corrosion and is used in oil machine construction.

A. I. Sokola (Serp i Molot Plant) discussed the embritt lement of austenitic- ferritic steels of the Kh15N12G2T type. According to the author, the cause of embrit t lement at 650-900~ is the formation of o-phase and the cause of embrit t lement at 450-600~ is the precipitation of the Nia(Ti, A1) phase in the ferritic component.

S e c t i o n on Use o f E l e c t r i c H e a t i n g in H e a t T r e a t m e n t o f S t e e l The review of this subject was presented by I. N. Kidin and A. N. Marshalkin (Moscow Institute of Steels and

Alloys). The authors showed that induction heating changes the kinetics of austenitic transformation and affects the properties of quenched products.

In the case of high frequency heating the a ~ 7 transformation occurs at higher temperatures. The austenite formed as the result of high frequency heating has much smaller grains and less uniform distribution of carbon and the alloyed elements as compared to that resulting from heating in ordinary furnaces.

These singularities decrease the strength of austenite during supercooling. The cooling rate has a great effect on the resistance of austenite obtained as the result of high frequency heating. The steels quenched after high frequency heating have higher hardness, higher resistance to low plastic deformation, higher impact strength, and higher wear resistance than steels quenched after ordinary heating.

It was noted that the use of high frequency heating can be very advantageous for increasing the rate of heat

treatment processes.

I. N. Kidina, M. A. Shtremel, and V. I. Lizunov (Moscow Institute of Steels and Alloys) discussed in great detail the mechanism of the c~--, ?, transformation resulting from high frequency heating of the Fe+ 8% Cr alloy on

the basis of dislocation concepts.

G. F. Golovin, A. D. Demichev, and E. V. Kushch (NIITVCh) described practical applications of high frequen- cy heating in heat treatment of gears. The authors developed a technique and an apparatus for quenching parts of the "Kirovets" tractor (40KhN steel) which ensures the desired shape and depth of the quenched layer inducing mini- mum deformation of the article. This apparatus eliminates the necessity of grinding gears after quenching.

1 P. A. Lankin (Central Scientific Research Institute of Machine Construction) described the advantages of con-

tour quenching of gears. For example, gears of steel No. 50 quenched after high frequency heating of the edges of the teeth are 2-2.5 times more wear resistant than the same gears made of 12Kh2N3A steel subjected to case hard-

ening and quenching.

V. P. Eremin and Yu. M. Bogatyrev (Central Scientific Research Institute of Machine Construction) described methods of heat treating clutch couplings which change the size very little. The authors found that the greatest deformation of clutch bushings occurs as the result of heating to quenching temperatures in the furnace and the smallest deformation results from induction heating and subsequent self-tempering. In the case of clutch bands, the best results were obtained by heating in an induction furnace followed by isothermal quenching, although this

method of heat treatment is rather complex.

P. I. Rusin (Rostov Institute of Agricultural Machine Construction) described some problems of high frequency treatment of cast iron. He showed that in the case of induction heating, unlike the case of heating in the furnace, free carbon in ferrite and ferritic-pearlitic cast iron dissolves mainly by diffusion into the austenite grains and

partially along the grain boundaries.

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The quenchabil i ry of cast iron increases with increasing numbers of graphite inclusions per unit area. The

author also gave data on the variat ion of the structure of the quenched layer as a function of the parameters

induction heat ing and the composi t ion of the cast iron.

S e c t i o n on t h e P r e s e n t S t a t e a n d t h e F u t u r e o f t h e D e v e l o p m e n t o f C h e m i e o t h e r m a l T r e a t m e n t

Yu. M. Lakhtin (MAD!), Yu. N. Griboedov (TsNIITMASh), G. N. Dubinin (MAI), A. T. Kalinin (NIITAvtoprom), and A. N. Minkevich (Moscow Institute of Steels and Alloys) presented a review. They described the present state

and probable future of the appl ica t ion of chemico the rmal t rea tment in industry for the t rea tment of machine parts and tools. They gave part icular at tention to modern types of chemico the rmal t rea tment : sulfocyaniding, low tempera ture gas cyaniding of structural steels, nitriding in a glow discharge, and atso diffusional me ta l l i za t i on (aluminum and chromium coatings) and coat ing of s teel with boron and silicon.

Spec ia l sections of the report concerned chemico the rma l t rea tment of t i t an ium, copper, and refractory metals .

I. S. Kozlovskii (Moscow Automechanica l Institute), E. A. Lebedev, and A. T. Kalinin (NIITAvtoprom) dis- cussed the effect of the parameters of case hardening on the strength of case hardened steel.

According to these authors, to obtain high qual i ty art icles it is necessary to precoot them in an endothermic atmosphere with a constant carbon potent ia l (0.8-0.95%) and one must introduce into the chamber of the furnace 5~ NH a 10 rain before the end of the process. The hardness of the center of the m e t a l after the chemico the rmal t rea tment must be not lower than HPC 30.

G. V. Zemskov and N. G. Kaidash (Odessa Polytechnical Insti tute) reported on experiments concerning borat- ing, borosi l ieiding, and bora luminiz ing of steel. They described the structure and the properties of surface layers and the d i s t r~u t ion of residual stresses over the cross section of samples.

A, G. Andreeva, G. D. Fomenko, V. S. Egorov, V. V. Khodov, and Z. A. Shevankova described very interest- ing results concerning the effect of nitr iding, n i t rocementa t ion, and cementa t ion conditions on the properties of stainless s teel art icles. The authors showed that nirriding considerably increases the wear resistance of machine parts subjected to high temperatures without decreasing their l i fe t ime.

S e c t i o n on C o n t r o l l e d A t m o s p h e r e s a n d T h e i r U s e in H e a t T r e a t m e n t a n d C h e m i c o - t h e r m a l T r e a t m e n t

A review was presented by A. A. Shmykov (Moscow Institute of Electronic Machine Construction). The author described in de ta i i the properties of different controlled atmospheres, the methods of their preparat ion, and their use at home and abroad.

The author listed the problems which must be solved before control led atmospheres can be used on a large scale in heat t rea tment operations.

Other reports described the different types of equipment for preparing control led atmospheres, apparatus for their control, and also the use of some of these atmospheres in the me ta l lu rg ica l and machine construction industries.

These reports were: "Standard equipment for the preparation of controlled atmospheres ~ byI . I. Maergoiz (VNII~TO), ~Controlled atmospheres used in the mining industry ~ byB. V. Malyshev (Stal 'proekt) , nUniversal controlled atmos-

phere made from natural gas ~ by A. A. Skvortsov and N. A. Ti tov (Gor 'k i i Poly technica l Institute), "Effect of con- trolled atmospheres on the properties of highly a l loyed steels and alloys" by A. A. Nilov and N. A. Balanaeva (Kazan ' ) , and ~Apparatus for control of protect ive atmospheres n by K. B. Dneprenko and V. S. MogiPchenko.

In conclusion, an announcement was made about the D. I. Chernov and N. A. Minkevich compet i t ions organ- ized by the Meta l Science and Heat T rea tmen t Journal, and the judging commi t t ee presented its report.

The meet ing concluded with a discussion of the further development of the science of the properties of steels and alloys and the pract ice of heat t rea tment .

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