ArcelorMittal S.A.
Method for producing a steel part and corresponding steel part

Abstract:

A method for producing a steel part and corresponding steel part includes casting a steel having a composition comprising: 0.10%.ltoreq.C.ltoreq.0.35%, 0.8%.ltoreq.Si.ltoreq.2.0%, 1.8%.ltoreq.Mn.ltoreq.2.5%, P.ltoreq.0.1%, 0%.ltoreq.S.ltoreq.0.4%, 0%.ltoreq.Al.ltoreq.1.0%, N.ltoreq.0.015%, 0%.ltoreq.Mo.ltoreq.0.4%, 0.02%.ltoreq.Nb.ltoreq.0.08%, 0.02%.ltoreq.Ti.ltoreq.0.05%, 0.001%.ltoreq.B.ltoreq.0.005%, 0.5%.ltoreq.Cr.ltoreq.1.8%, 0%.ltoreq.V.ltoreq.0.5%, 0%.ltoreq.Ni.ltoreq.0.5%, to obtain a semi-product, hot rolling the semi-product at a hot rolling starting temperature higher than 1000.degree. C. and cooling the product through air to room temperature to obtain a hot rolled steel part having a microstructure consisting of 70% to 90% of bainite, 5% to 25% of M/A compounds and at most 25% of martensite. The bainite and the M/A compounds contain retained austenite such that the total content of retained austenite in the steel is comprised between 5% and 25%, the carbon content of the retained austenite being comprised between 0.8% and 1.5%.