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1.
1.  Rolling of steel at 1100° and higher leads to austenite grain growth after annealing.
2.  A recrystallization threshold appears with plastic deformation at temperatures up to 1100°, the range of the recrystallization threshold broadening as the temperature of the preceding plastic deformation decreases. Plastic deformation =20% at 1150° always leads to a jump of austenite grain growth with repeated quenching, and for steel rolled at 1150 and 1200° the region of austenite grain growth broadens to =30–40%.
3.  At all degrees of deformation at different temperatures the average diameter of austenite grains decreases with decreasing preliminary rolling temperatures and increasing degrees of repeated plastic deformation. This undoubtedly affects the consistency of the properties inherited by high-speed steel during subsequent high-temperature plastic deformation.
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2.
1.  The hot deformation of corrosion-resistant steels of the ferritic, austenitic, and austenitic—ferritic classes in the 900–1100°C interval at rates sec–1 results in dynamic recrystallization.
2.  Various types of substructures are formed in the initial stages of plastic flow, depending on the deformation conditions and the type of crystal lattice of the steels, and, consequently, different mechanisms of dynamic recrystallization are realized.
3.  Substructure formation in the initial grains and gradual transformation of low- to high-angle boundaries are the mechanisms responsible for the formation of recrystallized grains in the ferritic steels over the entire temperature region investigated, and in the austenitic-class steel at high temperatures.
Institute of Problems of Metal Superplasticity, Ufa. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 5, pp. 19–23, May, 1992.  相似文献   

3.
Conclusions  
1.  Recrystallization of steels after hot rolling with a low reeling temperature begins and ends at a higher temperature and a longer hold than in steels obtained with reeling at a higher temperature.
2.  After hot rolling with a high reeling temperature the recrystallization of steel not bearing excess elements in the solid solution (Nb/C ef ≅1) begins and ends much more rapidly than recrystallization in the other steels.
3.  After continuous annealing, the ferrite grains in steel with Nb/C ef ≅1 have a maximumsize, which is connected with the leading recrystallization of this steel.
4.  The growth of ferrite grains in steel subjected to high-temperature reeling is accompanied by a decrease in the yield point and an increase in the specific elongation and coefficient of normal plastic anisotropy. Steels with Nb/C ef ≅1 have maximum mechanical properties.
Translated from Metallovedenie i Ternicheskaya Obrabotka Metallov, No. 7, pp. 14–17, July, 2000.  相似文献   

4.
Conclusions  
1.  The structure of powder white iron at a content of carbide phase amounting to from 40 to 60% virtually does not change relative to the initial (annealed) state in the process of plastic deformation.
2.  Hot plastic deformation without subsequent heat treatment affects the level of mechanical properties and the wear resistance of powder white iron comparatively weakly.
3.  Heat treatment increases the level of mechanical properties and the relative wear resistance of powder white iron, the effect being the most significant at 2.5–3%C.
Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 5, pp. 20–23, May, 1999.  相似文献   

5.
Conclusions  
1.  VChShG can be subjected to different kinds of plastic deformation without failure.
2.  In the process of plastic deformation of cast VChShG, graphite inclusions irreversibly lose their globular shape, extending along the direction of metal flow in the deformation source. Subsequent heat treatment affects only the microstructure and the morphology of the phases that compose the metallic matrix and does not affect the shape of graphite inclusions. This determines the level and the isotropic nature of the mechanical properties of semifinished products of VChShG fabricated by plastic deformation of cast preforms and imposes certain constraints on the production process and the quality parameters of ready articles.
3.  VChShG are susceptible to decarburization of the surface layer in heat treatment or heating for deformation in a furnace with an oxidizing atmosphere, which should be taken into account in designing the method of their deformation.
Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 11, pp. 21–25, November, 1999.  相似文献   

6.
1.  Recrystallization of deformed ferrite in steel R6M5 commences at about 780°C and it continues to the maximum recrystallization temperatures for existence of -solid solution. The temperature ranges for recrystallization and superplasticity coincide.
2.  Dynamic recrystallization of ferrite in steel R6M5 with rolling for one pass is incomplete with all degrees of deformation.
3.  Static recrystallization occurs entirely with 50%. The recrystallized ferrite grain size is finer than the original by a factor of four to five.
4.  Polygonization of deformed ferrite may markedly stabilize the structure and there-by make recrystallization difficult.
Polytechnic Institute, Tomsk. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 11, pp. 39–41, November, 1991.  相似文献   

7.
1.  Thermal cycling treatment leads to more dispersed precipitation of hardening phases in comparison with artificial aging of the same length as the thermal cycling treatment.
2.  The level of properties after thermal cycling treatment depends little upon the intensity of the thermal cycles.
3.  Thermal cycling treatment of wrought alloys of the Al-Mg-Si system increases their toughness and plastic properties (by 1.5–2.0 times) while the strength characteristics are somewhat lower than after T1 treatment.
4.  The cycles of mechanical-thermal cycling treatment including hardening, cold plastic deformation in the freshly hardened condition, and thermal cycling treatment make it possible to obtain high strength and electrical conductivity, the level of which depends upon the degree of deformation, the parameters of the thermal cycles, and the hold time at the maximum thermal cycle temperature.
5.  Low-temperature thermal cycling treatment including hardening and repeated deformation with thermal cycles in the intervals between passes is promising for treatment of aluminum alloys.
Leningrad Polytechnic Institute. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 7, pp. 49–53, July, 1989.  相似文献   

8.
Conclusions  
1.  The dissolution of the excess Laves phase in alloy 36NKhTYuM8 under the conditions of rapid quenching is maximum in the stage of heating to 1200°C, and the efficiency of the treatment increases in proportion to the heating rate. We have suggested an explanation of the determining role of the heating rate in the dissolution of the excess phase, which is based on the concept of high thermal stresses that appear on the interphase boundaries because of the difference in the coefficients of thermal expansion of the matrix and the phase.
2.  High plastic deformation of alloy 36NKhTYuM8 (ε=70%) is accompanied by deformation and cracking of the particles of the excess Laves phase, but the nonequilibrium nature of the structure of these particles does not influence noticeably their solubility under the conditions of rapid heating.
3.  The process of primary recrystallization that occurs in deformed alloy in the stage of rapid heating does not stimulate the dissolution of the excess phase, which means that the efficiency of rapid heating in quenching of alloys can be used independently of their initial state.
Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 6, pp. 13–19, June, 2000.  相似文献   

9.
1.  The presence of large grains on the surfaces of parts made from plates produced at the Zaporozhstal' Factory and annealed at 800\dg is due to the critical degree of rolling reduction.
2.  The critical degree of rolling reduction leads to grain growth as the result of secondary recrystallization in the process of annealing at 800°. It is recommended that plates be subjected to recrystallization annealing at 600°.  相似文献   

10.
1.  Increasing the strain rate from 6 to 4000 mm/min improves the strength characteristics of alloy KhN62BMKTYu at all test temperatures between 950 and 1150°C. Increasing the strain rate to more than 4000 mm/min barely changes the strength of the alloy.
2.  The maximal ductility of the deformed alloy KhN62BMKTYu corresponds to the temperature of dynamic recrystallization.
3.  Deformation of the alloy under temperature-strain-rate conditions (t=1150°C, v=6 mm/min) ensuring dynamic polygonization predetermines its high technological ductility.
4.  Specimens with structure type necklace have practically the same ductility as those with fully recrystallized structure.
5.  The temperature-strain-rate conditions t=1150°C, v=5000 mm/min are critical for alloy KhN62BMKTYu. Under these conditions the alloy fails without macroplastic deformation and without dynamic recrystallization.
A. A. Baikov Institute of Metallurgy. Translated from Metallovedenie i Termicheskaya i Obrabotka Metallov, No. 10, pp. 21–23, October, 1991.  相似文献   

11.
1.  The heat resistance of rods of dispersion-hardened alloy VDU-2 depends on the total deformation of the original compacts and the temperature of recrystallization annealing, and is almost independent of the ratio of deformation during extrusion and during cold drawing.
2.  The selection of the specific conditions of thermomechanical treatment is one of the most important steps in the development of dispersion-hardened alloys and an indispensable condition for obtaining high heat resistance.
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12.
Conclusions  
1.  Deformation of pseudo-α-alloy under a temperature and rate regime that provides the occurrence of the process of dynamic recrystallization of the β-phase independently of the deformation scheme, promotes the formation of a multi-component texture with disperse and uniform arrangement of the texture components having the same crystallographic orientation. The structure of the alloy consists of recrystallized β-grains with a lamellar transcrystalline structure and individual round uniformly distributed α-grains. Such a state of structure and texture provides isotropic properties in the plane of the sheet and a high resistance to LCF in a corrosive medium.
2.  Deformation under temperature-and-rate regimes that do not provide processes of dynamic recrystallization of the β-phase leads either to the formation of a predominantly prismatic structure or a texture with deviated basal plane with a band pattern of texture components with the same crystallographic orientation and a band structure independently of the deformation scheme. In the presence of a prismatic texture, the mechanical properties are substantially anisotropic and the resistance to LCF in a corrosive medium diminishes in the transverse direction.
3.  The test method employing a plastometer used in the present work allowed us to determine the temperature and deformation range of the formation of specific structure and texture states in pseudo-α-alloy with a sufficiently high reliability.
Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 9, pp. 38–44, September, 1999.  相似文献   

13.
1.  Austenite grain refining in maraging Cr–Ni steels occurs during heating due to recrystallization of phase strain-hardened austenite.
2.  Depending on the additional alloying, grain refining occurs either by the mechanism of nucleation of new grains (primary recrystallization)—steels with aluminum, copper, and cobalt, and steel without alloying additions—or by the mechanism of uneven migration of sections of the original boundary—steels with additions of molybdenum or titanium.
3.  The recrystallizationn mechanism determines the optimal temperature range, the number of times the steel must be heated for recrystallization, and its effectiveness. The degree of refining of the original coarse grains during primary recrystallization is approximately 30 times larger than with recrystallization by means of uneven migration of the original grain boundaries.
4.  For steels with aluminum, copper, and cobalt that contain <0.03% c=" the=" optimal=" recrystallization=" temperature=" is=" equal=" to=" 850–880°=" with=" double=" austenitizing.=" for=" steels=" with=" molybdenum=" and=" titanium=" the=" optimal=" recrystallization=" temperature=" is=" 960–1025°,=" depending=" on=" the=" composition,=" with=" austenitizing=" three=" times.=">
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14.
1.  Primary recrystallization of metals is accompanied by emission of electrons. The kinetics and parameters of the emission current are determined by the development of recrystallization.
2.  The exoelectronic emission observed is due to the evolution of energy during relaxation of internal stresses in the crystal lattice.
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15.
1.  Significant thermal stability of the hardened condition of strongly worked low carbon steel is obtained by cyclic deformation by alternating sign bending.
2.  The effect of stabilization of the hardened condition of strongly cold-worked low-carbon steel is determined by the reduction in integral energy and in volumetric integral of this energy in cyclic deformation. In post-deformation heating softening of the steel additionally retards blocking of the dislocations by impurity atoms supplied by the cementite. As the result processes of both primary and accumulative recrystallization are retarded.
3.  Preservation of the increased strength of cyclic deforamtion-stabilized cold-worked steel is determined by preservation of the increased dislocation density distributed in the walls of the dislocation fragments and by some decrease in the average ferritic grain size.
Dnepropetrovsk Metallurgical Institute. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 2, pp. 26–30, February, 1992.  相似文献   

16.
1.  When films with a cobalt and a chromium layer with respective thickness 50 and 500 nm are heated to 250–350°C, recrystallization occurs, resulting in the orientation Co (1011)/Cr (110) changing to Co (1120)/Cr (100).
2.  In recrystallization the grain size remains almost unchanged. Grain growth is encountered solely during further heating.
3.  A change of the orientation of the CoNi/Cr film in recrystallization leads to an increase of the coercive force and of the ratio Br/Bm.
MIÉM. Scientific and Production Association "Vakuummashpribor." Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 1, pp. 46–48, January, 1992.  相似文献   

17.
Conclusions  
1.  The heating rate in short-term service of parts from cold-deformed niobium, molybdenum, and their alloys in a gas medium can exert either a hardening or a softening action depending on the kinetics of the occurring hardening (solid-solution and substructural hardening) and softening (return and recrystallization) processes.
2.  Optimum regimes have been found for heat treatment of nickel-base high-temperature alloys for short-term operation with initiation of overheating relative to the service temperature. The permissible loads are 10–25% higher than after a standard heat treatment.
3.  The determination of the laws of the occurrence of the hardening and softening processes in high-temperature materials under unsteady temperature and time conditions makes it possible to make a substantiated choice of the material and hence provide a higher reliability of the structure in service.
Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 4, pp. 20–22, April, 1999.  相似文献   

18.
Conclusions  
1.  The ingot from the Mourner mine (Central Balkans) is represented by bronze, i.e., a natural alloy whose composition includes (in the order of decreasing content) iron, zinc, arsenic, sulfur, nickel, silver, and antimony. Its natural appearance in the smelting process is explainable by the fact of the existence of a polymetal ore in the mine.
2.  The ingot from Kargaly (Southern Urals) is represented by ideally pure copper with globular inclusions of Cu2S sulfides located along grain boundaries and in the bulk of the grains. This gives us grounds to assume that the oxidized ore from which the Kargaly copper was melted contained sulfur-bearing components. The same inference follows from the results of the study of a pricker made of the Kargaly copper.
3.  Analyzing the microstructure and hardness of the Kargaly copper in studying the pricker we established that cast copper was subjected to cold plastic deformation and shortterm recrystallization annealing in the second millennium B.C.
4.  We detected a sulfur admixture in copper specimens melted from ores fundamentally different in their mineralogical and geochemical characteristics. This means that quite substantial corrections should be made in the existing concept that this impurity can appear only due to the melting of primary or sulfide ores. Consequently, we should reconsider the conclusion that the sulfur impurity has a decisive role in studying the technology of ancient pyrometallurgy.
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19.
1.  Brittle fracture and the decrease in the strength of materials under the action of molten solder are connected with the marked decrease in their plasticity caused by the intensification of the decomposition of the solid solution with segregation of particles of hardening phases in the alloys supplemented with a α→γ transformation in the steels.
2.  The enhancement of the sensitivity to embrittlement in specimens with a stress concentrator (a notch) or with coarse grains in contact with molten solder is due to the intensification of the processes connected with the appearance of stresses and inhibition of plastic deformation. In the presence of coarse grains this is also connected with the elevation of the density of segregations over grain boundaries (the total length of grain boundaries decreases).
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20.
1.  The high-temperature ductility of the dispersion-hardening nickel alloy KhN60KVMYuB at a deformation rate corresponding to that occurring during extrusion is adequate in the temperature range 1040–1190°C. Below 1040°C the ductility is low due to the presence of a large volume fraction of -phase in the structure.
2.  Deformation of the cast alloys at 1100–1190° is accompanied by dynamic recrystallization, as a result of which, in the absence of a second phase, a fine grained structure is formed (including a "necklace" type of structure) which posesses high ductility.
3.  The temperature range of high ductility coincides with the range of dynamic recrystallization in the alloy resulting in the formation of grains with an average size of less than 100 m.
4.  Dynamic collective recrystallization leads to the formation of a coarse-grained structure with grain boundaries of low mobility. This structure has low resistance to the initiation of interfacial cracks, and their growth under applied load.
Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 1, pp. 13–17, January, 1992.  相似文献   

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