Metal Science and Heat Treatment

Dubinin, G.

doi: 10.1007/BF02471341pmid: N/A

This paper concerns the results of metallographic and electron-microscopic studies of columnar crystals in the diffusion layer of alloys that appears due to the diffusion of various elements of the metallic group in the presence of a polymorphic transformation on the isotherm of the process and in its absence. In contrast to the earlier existing standpoint that columnar crystals form in the diffusion layer only in the case where the diffusion is accompanied by a polymorphic transformation of the structure, it is shown that they appear in solid solutions whose isotherm does not exhibit phase recrystallization. A hypothesis of the mechanism of formation of the columnar structure is presented.

Kulikov, A.

doi: 10.1007/BF02471342pmid: N/A

1. A new method of surface impregnation, i.e., chromophosphating, has been suggested which consists in passivating the surface of the parts (a hold in aqueous solutions of AKhFS or MIKS) followed by a heat treatment typical for the parts. 2. As a result of chromophosphating the hardness of the surface of parts manufactured from cast iron and steel increases, its roughness decreases, and the corrosion resistance improves.

Teleshov, V.; Vorob'ev, N.

doi: 10.1007/BF02471343pmid: N/A

1. The use of maximum values of the strength properties of alloys in state T1 (σГmax,σ0.2max) as an independent characteristic allows us to obtain general linear equations of multiple regression that describe the dependence of the strength properties of pressed bands after heating at 175°C on the chemical composition of alloys of the Al−Cu−Mg system with high (type D21) and low (VD17) Cu/Mg ratio. 2. Softening of all the studied alloys with various Cu/Mg ratios at 175°C for each kind of test is connected through the general equation with the content of individual alloying components in the alloy. In accordance with the strength properties exhibited in various kinds of test alloys, D19ch, VD17, and AK4-2ch are the best.

Shneider, G.

doi: 10.1007/BF02471344pmid: N/A

Il'ina, V.

doi: 10.1007/BF02471345pmid: N/A

1. The improvement of the purity of high-strength steel 38Kh5MSFA (with respect to S and P harmful admixtures, gas saturation, and nonmetallic impurities) has a positive effect on the characteristics of plasticity and toughness of the steel. The anisotropy of these properties diminishes, especially the susceptibility of the steel to brittle fracture;KCT of the metal molten from “pure” charge materills by the vacuum induction method after quenching from 1000°C and tempering at 300°C is 1.5–2.5 times higher than that of the metal fabricated from conventional charge materials by open melting. The values of σ Г t andK c of the “pure” heat are 30% higher than those of the conventional heat, which indicates that the reliability of the parts produced from this steel should be higher. 2. Improvement of the purity of the steel decreases considerably its susceptibility to corrosion cracking; after heat treatment by the optimum regime and tensile test in the atmosphere of a salt fog the life of specimens of “pure” metal is 22 days and that of specimens of conventional metal is 15 days.

Zheltov, Yu.; Kosonogova, S.; Morozov, V.

doi: 10.1007/BF02471346pmid: N/A

The results of a study of probabilistic distributions of hardness in H-bands of steels 30KhM and 20KhGNM are presented. The coefficients of regression and correlation between the hardness and the content of the alloying components are obtained for various distances from the ends of the quenched specimens. The study has been performed by the method of computer statistical processing of the density of distribution of the hardenability curves in H-bands of the steels. The results are shown to be applicable for predicting the correspondence between the hardness in critical cross sections of steel parts and the specified requirements.