ArcelorMittal S.A.
PRESS HARDENED PART WITH HIGH RESISTANCE TO DELAYED FRACTURE AND A MANUFACTURING PROCESS THEREOF

Abstract:

A press hardened coated steel part with high resistance to delayed fracture, the coating containing (Fe.sub.x--Al.sub.y) intermetallic compounds resulting from the diffusion of iron into an aluminum or an aluminum-based alloy, or an aluminum alloy of a precoating, wherein the chemical composition of the steel includes, in weight: 0.16%.ltoreq.C.ltoreq.0.42%, 0.1%.ltoreq.Mn.ltoreq.3%, 0.07%.ltoreq.Si.ltoreq.1.60%, 0.002%.ltoreq.Al.ltoreq.0.070%, 0.02%.ltoreq.Cr.ltoreq.1.0%, 0.0005.ltoreq.B.ltoreq.0.005%, 0.002%.ltoreq.Mg.ltoreq.0.007%, 0.002%.ltoreq.Ti.ltoreq.0.11%, 0.0008%.ltoreq.O.ltoreq.0.005%, wherein (Ti).times.(O).sup.2.times.10.sup.7.ltoreq.2, 0.001%.ltoreq.N.ltoreq.0.007%, 0.001%.ltoreq.S.ltoreq.0.005%, 0.001%.ltoreq.P.ltoreq.0.025% and optionally one or more elements selected from the list of: 0.005%.ltoreq.Ni.ltoreq.0.23%, 0.005%.ltoreq.Nb.ltoreq.0.060%, the remainder being Fe and unavoidable impurities, and wherein the microstructure includes at least 95% martensite.