METHOD OF MAKING A HIGH-STRENGTH STEEL ARTICLE AND A STEEL ARTICLE OBTAINED IN SUCH A WAY Russian patent published in 2019 - IPC C21D7/13 C22C38/58 C21D8/02 C21D8/00 

FIELD: metallurgy.

SUBSTANCE: method involves the steps of: obtaining a heated steel starting article at temperature of 380–700 °C, having a metastable austenite structure and containing, wt%: 0.15≤C≤0.40, 1.5≤Mn≤4.0, 0.5≤Si≤2.5, 0.005≤Al≤1.5, wherein 0.8≤Si+Al≤2.5, S≤0.05, P≤0.1, at least one element of: Cr and Mo: 0≤Cr≤4.0, 0≤Mo≤0.5 and 2.7≤Mn+Cr+3 Mo≤5.7, and optionally one or more elements of: Nb≤0.1, Ti≤0.1, Ni≤3.0, 0.0005≤B≤0.005, 0.0005≤Ca≤0.005, the rest is iron and unavoidable impurities, the hot-forming step is carried out at temperature of 700 to 380 °C, with total deformation ε_b from 0.1 to 0.7 in at least one heated steel article location to produce a completely austenitic structure of hot-molded steel article, after that hardening of hot-molded steel item by cooling at cooling rate VR₂, which exceeds critical martensite cooling rate, to QT temperature lower than Ms, to obtain structure containing 40 to 90 % of martensite, austenite, after that, preservation of the product at the PT holding temperature in the range from QT to 470 °C or reheating of the article to the said temperature and holding at temperature PT for the period of time Pt from 5 s to 600 s.

EFFECT: improved mechanical characteristics of the steel article.

25 cl, 6 dwg, 3 tbl