公开(公告)号：US11773464B2

公开(公告)日：2023-10-03

申请号：US17275157

申请日：2019-09-20

Applicant: ArcelorMittal

Inventor： Pascal Drillet ,  Raisa Grigorieva ,  Thierry Sturel ,  Cédric Georges ,  Brahim Nabi ,  Florin Duminica

IPC: C21D9/46 ,  C21D1/673 ,  C21D1/70 ,  C23C2/28 ,  B32B15/01 ,  C22C21/02 ,  C22C38/54 ,  C22C38/50 ,  C22C38/46 ,  C22C38/44 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/42 ,  C22C38/48

CPC classification number: C21D9/46 ,  B32B15/012 ,  B32B15/013 ,  C21D1/673 ,  C21D1/70 ,  C22C21/02 ,  C22C38/001 ,  C22C38/002 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/54 ,  C23C2/28 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008

Abstract: A press hardening method includes the following steps providing a carbon steel sheet coated with a barrier pre-coating including nickel and chromium wherein the weight ratio Ni/Cr is between 1.5 and 9, cutting the sheet to obtain a blank, thermal treatment of the blank in an atmosphere having an oxidizing power equal or higher than that of an atmosphere consisting of 1% by volume of oxygen and equal or smaller than that of an atmosphere consisting of 50% by volume of oxygen, such atmosphere having a dew point between −30 and +30° C., transfer of the blank into a press tool, hot-forming of the blank to obtain a part, cooling of the part to obtain a microstructure in steel being martensitic or martensito-bainitic or made of at least 75 wt. % of equiaxed ferrite, from 5 to 20 wt. % of martensite and bainite in amount less than or equal to 10 wt. %.