Metal Science and Heat Treatment

Egorov, Yu.; Khazanov, I.

doi: 10.1007/BF00769356pmid: N/A

1. The main processes determining the formation of the austenitic structure in deformed steel R6M5 during heating to quenching temperature and in the process of holding at this temperature are polygonization and recrystallization. 2. With deformation near the critical the recrystallization process proceeds by recrystallization in place, which leads to sudden austenite grain growth. 3. The proposed recrystallization mechanism with near-critical deformation is based on the possibility of a section of high-angle boundary transforming to a section with a low-angle misorientation in the process of recrystallization in place and later avalanchelike combination of original austenite grains. 4. The difference in the grain sizes of the recrystallized austenite grains is highest at deformations of 10 and 50%. The difference in grain sizes with 10% deformation is due to formation of large grains, and with 50% deformation to formation of small grains.

Popandopulo, A.; Popova, S.; Sil'nikova, E.

doi: 10.1007/BF00769357pmid: N/A

1. Tungsten-molybdenum. high-speed steels are susceptible to intercrystalline fracture. 2. Spontaneous recrystallization of austenite and solution of carbides precede sudden grain growth. 3. The sudden grain growth occurs by the fusion mechanism. 4. The fusion and growth of silky grains occur within the limits of the original grains.

Smol'nikov, E.; Orestova, L.

doi: 10.1007/BF00769358pmid: N/A

1. In individual cases with the necessity of rapid annealing of high-speed steel together with stepless annealing at 885–675°C, which is done in a single salt bath, cyclic stepped annealing in two salt baths with temperatures of 850 and 700°C and holds in each of them at from 10 to 30 min may be used. 2. The total time for accelerated cyclic annealing is no more than 1–7 h and increases within these limits with an increase in the temperature of the preliminary heating, with an increase in the cobalt content in the steel, and with the use of welded pieces. 3. It is more rational to use stepless cyclic annealing for small diam. (≤30 mm) solid and welded pieces while stepped cyclic annealing may be used for larger pieces. The total annealing time of cylindrical pieces is determined from the equation τann =aD + C wherea is a coefficient which is dependent upon the preliminary hot working conditions, D is the diameter of the piece in mm, and C is the additional time for completion of transformation in the steel. 4. In comparison with isothermal annealing, cyclic annealing using the recommended cycles provides a decrease in the width of the ferrite zone of welded parts in the area of the joint. 5. The structure, distribution, and chemical composition of the carbide phase after cyclic and after isothermal annealing differ very little, which is indicated by the results of hardness measurement.

Lyadskaya, A.; Mel'nichenko, A.; Spuskanyuk, V.; Tkachenko, F.; Trankovskaya, L.

doi: 10.1007/BF00769359pmid: N/A

1. The crystalline structure defects of tool steels created by cold hydroextrusion in the ferrite-pearlite condition are characterized by high thermal stability. The alloy content of the worked material and the presence of excess carbide phase promote preservation of this stability. 2. In hydroextruded high-speed steels the austenite is more stable in the pearlite area than in the undeformed and in ShKh15 it is the opposite. 3. Hydroextrusion of high-speed steels leads to a reduction in the temperature of the start of the martensite transformation in their subsequent heat treatment.

Tishaev, S.; Politaev, Yu.

doi: 10.1007/BF00769360pmid: N/A

1. The composition of a tool steel with increased service properties for pressure casting molds may be calculated by mathematical statistics methods using the "compromise" principle. 2. The experimental steel of the calculated type 3Kh3VMF composition for molds for pressure casting copper base alloys is significantly better than standard steels for the same purpose, particularly 4Kh4VMFS (DI22), 3Kh3M3F, and 3Kh2V8F, on the basis of the combination of mechanical properties and life.

Skrynchenko, Yu.; Terekhov, V.

doi: 10.1007/BF00769361pmid: N/A

1. Vacuum induction remelting and modification do not lead to an increase in ductile properties of 1V7M6K12 steel. 2. The impact strength of steel produced by the powder metallurgy method is 1.5–2 times greater than of normally melted steels but its absolute values are quite low. 3. Cyclic temperature—force action provides a substantial increase in the mechanical properties of the investigated steels.

Bernshtein, M.; Kaputkina, L.; Nikishov, N.

doi: 10.1007/BF00769362pmid: N/A

1. Varying the hot deformation conditions makes it possible to obtain a broad variety of structural and substructural conditions of austenite. Reducing the rate and raising the temperature makes it possible to obtain a polygonized substructure after hot deformation and retain it after cooling. 2. A homogeneous polygonized isotropic substructure with a fairly low density of dislocations within subgrains slows down the initial stages in the development of recrystallization under conditions of hot deformation and controlled postdeformation holding. This substructure can be obtained in the steady stage of hot deformation and also by the development of static polygonization processes during brief postdeformation holding. 3. Alloying with carbide-forming elements (chromium and manganese) inhibits the development of recrystallization (in comparison with alloying with nickel) even if the steel consists of a single-phase solid solution.

Bubenshchikov, A.; Nechaev, Yu.; Shekhter, L.

doi: 10.1007/BF00769363pmid: N/A

1. From the rate of the change in the temperature coefficient of electrical resistivity of Al−3.5% Cu in the solid-liquid state in the temperature range of 590–615° it was established that individual dislocations can serve as the centers of melting. 2. The activation energy of copper diffusion in aluminum E=144.4 kJ/mole.

Voronenko, B.

doi: 10.1007/BF00769364pmid: N/A

The phenomenon of acoustic emission can be used in studying the characteristic features of the mechanism, kinetics, and energy parameters of the martensitic transformation: determination of the martensite points and the amount of martensite that is formed, measurement of the rate of initiation and growth of martensite crystals, investigation of preliminary processes, establishment of the incubation period and the early stages of the formation of martensite, determination of the type of kinetics, structural mechanism, and morphology of the martensite that is formed, and the formation and annihilation of transformation twins, and determination of the degree of cooperativeness of the transformation, the presence and degree of the autocatalysis effect, and the heterogeneity of the shear strain during the transformation. The possibility of AE development during certain diffusion transformations requires confirmation. A more profound and objective investigation of the AE effect (among other things, a detailed study of the mechanism governing the development of AE signals and the identification of their sources), further improvement and standardization of the methods and equipment used are necessary.

Yuruts, N.; Aleksandrov, B.

doi: 10.1007/BF00769365pmid: N/A

1. With fatigue tests on helical gears the source of crack initiation is located in the trailing side of the teeth at a distance of 3–6 mm from its throat. After initiation the crack moves parallel to the base of the tooth to emerge at the second face and simultaneously into the tooth material. 2. The micromechanism of fatigue failure for carburized wheel teeth depends on stress amplitude. 3. Results of this work make it possible to set up criteria for analyzing conditions for formation of operational failure of helical gears.