Metal Science and Heat Treatment

Mints, R.; Petukhova, T.; Grokhovskii, V.; Shaldybin, V.

doi: 10.1007/BF00663077pmid: N/A

Vinograd, M.; Ul'yanina, I.; Faivilevich, G.

doi: 10.1007/BF00663078pmid: N/A

1. The use of high-temperature metallography and a vacuum stage makes it possible to reveal different mechanisms of austenite grain growth in carbon and alloy structural steels. 2. It was found that austenite grain growth occurs at 850–1250° by three different mechanisms: I) resorption of grains; II) formation of new boundaries and grains; III) boundary migration. The first and second mechanisms are accompanied by decomposition of old boundaries and the third is characterized by movement of the boundaries. 3. Resorption of grains predominates at temperatures 50–100° above Ac3, and the formation of new more even boundaries at temperatures 250–300° above Ac3. Boundary migration occurs at all temperatures but affects grain growth only above 1100°. 4. The resorption of grains evidently depends on rebuilding of dislocation arrays, and the formation of new grain boundaries on rebuilding of dislocation arrays and movement of atoms. The process of boundary migration may be determined by the movement of dislocation groups and collective diffusional movements of atoms.

Moiseev, B.; Brunzel', Yu.; Shvartsman, L.

doi: 10.1007/BF00663079pmid: N/A

1. From experimental data we plotted thermodynamic equilibrium diagrams of carbon in alloy steel at different carbon potentials of the atmosphere for 850, 950, and 1000°. 2. For alloy steels subjected to carburizing, bright quenching, or recarburizing it is possible to determine from the diagram the carbon potential of the atmosphere required to obtain the desired carbon concentration on the surface of the steel.

Korablev, V.; Ustinovshchikov, Yu.; Khatskelevich, I.

doi: 10.1007/BF00663080pmid: N/A

1. No embrittlement of chromium steels occurs if the M3C→M7C3 transformation does not occur during tempering. 2. Chromium steels are embrittled in the second stage of carbide formation if the solution of cementite creates conditions for the nucleation of finely dispersed chromium carbide M7C3 in slip planes formed in the process of the impact toughness tests. 3. Chromium steels are embrittled in the third stage of carbide formation if the microdistortion of the crystal lattice increases before the loss of coherency of M7C3 carbides with the matrix.

Volosevich, P.; Petrov, Yu.

doi: 10.1007/BF00663081pmid: N/A

The high dislocation density of austenite undergoing the γ→α→γ transformation is due to the influence of fresh dislocations that occur during the α→γ transformation in virtue of its martensitic character and to dislocations inherited from the original phases.

Popov, V.; Titukh, Yu.

doi: 10.1007/BF00663082pmid: N/A

X-ray diffraction analysis showed that strain martensite is formed in the surface layer during abrasive wear, the dislocation density increases, the lattice constant of austenite and the tetragonality of martensite change, and the residual stresses increase.

Geller, Yu.; Golubeva, E.; Goncharova, A.

doi: 10.1007/BF00663083pmid: N/A

1. The service life of pressure die-casting molds can be improved substantially by using corrosion resistant steels in place of the heat resistant die steels used at the present time. 2. The heat resistance of corrosion resistant steels can be improved by alloying with molybdenum and tungsten. 3. Steels 18Kh12VMBFR, 2Kh9V6, and 4Kh4MVFS are the most suitable for pressure die-casting molds used for copper alloys, and steels 2Kh9V6 and 2Kh10MFN and die steel 4Kh5MFS for aluminum alloys.

Griboedov, Yu.; Isakova, E.; Édel'man, A.; Nikitin, A.

doi: 10.1007/BF00663084pmid: N/A

1. The use of preliminary carburizing for steels 4Kh5MFS, 4Kh2M1FN, and 4Kh5V2FS results in a layer of chromium carbide 30–50% deeper after chromizing, and also a higher surface hardness after quenching and tempering. 2. Preliminary carburizing improves the heat resistance, red hardness, and hot wear as compared with diffusion chromizing (without carburizing) or standard heat treatment. 3. Production tests of mandrels and matrixes of cable presses made of steels 4Kh5MFS and 4Kh2M1FN indicate that after the combination treatment the durability is three to four times higher than that of tools made of steel 3Kh2V8F subjected to standard heat treatment.

Krishtal, M.; Renne, I.; Kisurin, A.

doi: 10.1007/BF00663085pmid: N/A

1. Hardening created by thermomechanical treatment is most effective under conditions of local 2. The treatment of steels by STMT is the most promising treatment due to its high technological efficiency.

Smol'nikov, E.; Sarmanova, L.

doi: 10.1007/BF00663086pmid: N/A

1. The susceptibility to decarburizing of the steels investigated increases in the following order: R6M5, R9M4K8, R6M5K5. 2. To prevent decarburizing of tools made of steels R6M5, R9M4K8, and R6M5K5 the minimal carbon content of control samples (bands of steel 13Kh) after heating at standard quenching temperature for 1 min should be 0.95–1%, as compared with the 0.85% required for quenching of steel R18. 3. The effect of the rectifiers tested increases in the following order: borax, ferrosilicon, magnesium fluoride. With periodic use of high-temperature salt baths one must add at least 0.6–0.8% borax and 0.35–0.50% ferrosilicon twice during the working shift and 0.6–0.8% magnesium fluoride once during the shift. in view of the low effectiveness of borax as a rectifier, it should be used only for quenching of tools heated for a short time. 4. Periodic additions of magnesium fluoride are possible in the absence of prepared mixtures of magnesium fluoride with barium chloride.