ArcelorMittal S.A.
METHOD FOR PRODUCING A STEEL PART AND STEEL PART

Abstract:

Method for producing a steel part comprising providing a semi-finished product made of a steel comprising, by weight: 0.35%.ltoreq.C.ltoreq.0.60%; 0.15%.ltoreq.Si.ltoreq.0.5%; 0.8%.ltoreq.Mn.ltoreq.2.0%; 0.0003%.ltoreq.B.ltoreq.0.01%; 0.003%.ltoreq.Mo.ltoreq.1.0%; 1.0%.ltoreq.Cr.ltoreq.2.0%; 0.01%.ltoreq.Ti.ltoreq.0.04%; 0.003%.ltoreq.N.ltoreq.0.01%; S.ltoreq.0.015%; P.ltoreq.0.015%; 0.01%.ltoreq.Ni.ltoreq.1.0%; 0.01%.ltoreq.Nb.ltoreq.0.1%; optionally 0.ltoreq.Al.ltoreq.0.1%; 0.ltoreq.V.ltoreq.0.5%; and the remainder consisting of iron and unavoidable impurities. The method further including annealing this semi-finished product at a temperature strictly lower than the Ac1 temperature of the steel; cold forming the semi-finished product into a cold formed product; subjecting the cold formed product to a heat treatment comprising heating the cold formed product to a temperature greater than or equal to the Ac3 temperature of the steel; and holding the product at a holding temperature comprised between 300.degree. C. and 400.degree. C. for a time comprised between 15 minutes and 2 hours.