WEAR-RESISTANT HEAVY PLATES WITH EXCELLENT LOW-TEMPERATURE IMPACT STRENGTH AND METHOD OF THEIR PRODUCTION Russian patent published in 2017 - IPC C22C38/32 C21D6/00 C21D8/02 

FIELD: metallurgy.

SUBSTANCE: steel has a chemical composition containing in wt %: C: 0.10 to less than 0.20, Si: 0.05 to 0.5, Mn: 0.5 to 1.5, Cr: 0.05 to 1.20, Nb: from 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, O: not more than 0.008, the rest is Fe and unavoidable impurities. Brinell hardness of steel (HBW10/3000) is 361 or more, and the microstructure contains fine precipitate with a diameter of 50 nm or less with a density of 50 or more per 100 mcm². The microstructure of the steel from the surface to the depth of at least 1/4 of thickness of the plate 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 has high hardness and low-temperature impact strength.

17 cl, 2 dwg, 2 tbl