WEAR-RESISTANT SHEET STEEL WITH EXCELLENT LOW-TEMPERATURE IMPACT STRENGTH AND RESISTANCE TO HYDROGEN ATTACK AND METHOD OF ITS MANUFACTURE

摘要

FIELD: metallurgy.;SUBSTANCE: steel contains, wt %: C: 0.20 to 0.30, Si: 0.05 to 0.5, Mn: 0.5 to 1.5, Cr: 0.05 to 1.20, Nb: 0.01 to 0.08, B: 0.0005 to 0.003, Al: 0.01 to 0.08, N: 0.0005 to 0.008, P: not more than 0.05, S: not more than 0.005 and O: not more than 0.008, the rest is Fe and unavoidable impurities. Brinell hardness of steel (HBW10/3000) is 401 or more, and the microstructure contains fine precipitate with a diameter of 50 nm or less with a density of 50 or more particles per 100mcm². The microstructure of the steel from the surface to the depth of at least 1/4 of the thickness is a rack martensite with an average grain size of not more than 20 mcm, the average grain size is the average size of crystalline grains surrounded by large-angle grain boundaries having a difference in orientation of 15° or more.;EFFECT: steel sheets have high low-temperature impact strength and resistance to hydrogen attack.;17 cl, 2 tbl