公开(公告)号：US11466335B2

公开(公告)日：2022-10-11

申请号：US16069804

申请日：2017-01-17

Applicant: ArcelorMittal

Inventor： Elena Uta ,  Veronique Hebert

IPC: C21D9/46 ,  B32B15/01 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/44 ,  C22C38/48 ,  C22C38/50 ,  C22C38/58 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40

Abstract: A cold rolled and heat treated steel sheet is provided. The steel sheet includes a composition including 0.17%≤carbon≤0.24%, 1.9%≤manganese≤2.2%, 0.5%≤aluminum≤1.2%, 0.5%≤silicon≤1%, Si+Al≥1.3%, 0.05%≤chromium≤0.2%, 0.015%≤niobium≤0.03%, sulphur≤0.003%, phosphorus≤0.03% and optionally 0.005%≤titanium≤0.05%, 0.001%≤molybdenum≤0.05%, a remainder of the composition including iron and the unavoidable impurities. A microstructure of the coated steel sheet includes, in area fraction, 10 to 20% residual austenite, said austenite phase having a carbon content between 0.9 to 1.1%, 40 to 55% polygonal ferrite, 15 to 40% granular bainite and at least 5% tempered martensite, a sum of tempered martensite and residual austenite being between 20 to 30%. A method is also provided.