Effect of the purity of the metal on the susceptibility of steel 38Kh5MSFA to brittle fracture
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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.
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.
KeywordsBrittle Fracture Impact Toughness Carbonyl Iron Charge Material Central Crack
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