FIELD: metallurgy.
SUBSTANCE: invention relates to metallurgy, namely to steel part obtained by cold forming, and can be used in automotive industry. Method of steel part manufacturing includes provision of semi-finished product made from steel, including, wt.%: 0.05 ≤ C ≤ 0.15, 0.01 ≤ Si ≤ 1, 1.2 ≤ Mn ≤ 2, 0.1 ≤ Cr ≤ 2, 0.001 ≤ Al ≤0.1, 0.003 ≤ N ≤ 0.01, 0 ≤ S ≤ 0.015, 0 ≤ P ≤ 0.015, optional 0 ≤ Ni ≤ 1, 0 ≤ B ≤ 0.01, 0 ≤ Mo ≤ 1, 0 ≤ Ti ≤ 0.04, 0 ≤ Nb ≤ 0.1, 0 ≤ V ≤ 0.5, rest is made up of iron and unavoidable impurities, annealing of semi-finished product at annealing temperature strictly below temperature Ac1 of steel, cooling to room temperature, cold moulding of the semi-finished product into a cold-formed article, thermal treatment of the cold-formed article. Thermal treatment includes heating of item to temperature of thermal treatment, which is higher or equal to temperature of complete austenisation Ac3 of steel, and quenching to room temperature. Optionally, the article is reheated at a holding temperature of 180 to 400 °C for from 15 minutes to 2 hours. Steel part has a microstructure comprising at least 80% of bainite by area and total presence of martensite and residual austenite from 1 to 25% by area, wherein steel part has ultimate tensile strength of 1,100 MPa or more.
EFFECT: obtained steel part has high mechanical properties and improved resistance to hydrogen embrittlement.
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