公开(公告)号：US20200224287A1

公开(公告)日：2020-07-16

申请号：US16827696

申请日：2020-03-23

Applicant: ArcelorMittal

Inventor： Dongwei FAN ,  Hyun Jo JUN ,  Rashmi MOHANTY ,  Pavan K. C. VENKATASURYA

IPC: C21D9/46 ,  C22C38/02 ,  C22C38/04 ,  C21D8/02 ,  C21D1/18 ,  C21D6/00 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40

Abstract: A method is for producing a high strength coated steel sheet having an improved ductility and an improved formability, and a chemical composition containing: 0.13%≤C≤0.22%, 1.9%≤Si≤2.3%, 2.4%≤Mn≤3%, Al≤0.5%, Ti≤0.05%, Nb≤0.05%, the remainder being Fe and unavoidable impurities. The sheet is annealed at temperature TA higher than Ac3 but less than 1000° C. for a time of more than 30 s, quenched by cooling to a quenching temperature QT between 200° C. and 280° C. in order to obtain a structure consisting of austenite and at least 50% of martensite, the austenite content being such that the final structure can contain between 3% and 15% of residual austenite and between 85% and 97% of the sum of martensite and bainite, without ferrite, heated up to a partitioning temperature PT between 430° C. and 490° C. and maintained at this temperature for a time Pt between 10 s and 100 s, hot dip coated and cooled to the room temperature.