HIGH-STRENGTH HOT-DIP GALVANNEALED STEEL SHEET HAVING EXCELLENT BAKE HARDENING PROPERTY AND BENDABILITY

摘要

The present disclosure relates to a high-strength hot-dip galvannealed steel sheet excellent in bake hardenability and bendability and having a component composition containing, in mass %, C: from 0.05 to 030%, Si: from 0.5 to 3.0%, Mn: from 0.2 to 3.0%, P: from 0 to 0.10%, S: from 0 to 0.010%, N: form 0 to 0.010%, and Al: from 0.001 to 0.10%, with the remainder being iron and unavoidable impurities. The steel sheet has a steel structure containing, in terms of area percentage, martensite: form 50 to 85% and ferrite: 0% or more and less than 5%, with the remainder being bainite. The steel sheet has a dislocation density of 5.0×1015 m−2 or more, a solute carbon amount of 0.08 mass % or more and a tensile strength of 1180 MPa or more.

主权项

1. A high-strength hot-dip galvannealed steel sheet excellent in bake hardenability and bendability, having a component composition comprising, in mass %:
C: from 0.05 to 0.30%. Si: from 0.5 to 3.0%, Mn: from 0.2 to 3.0%, P: from 0 to 0.10%, S: from 0 to 0.010%, N: from 0 to 0.010%, Al: from 0.001 to 0.10%, and iron and unavoidable impurities, and having a steel structure comprising, in terms of area percentage: martensite: from 50 to 85% and ferrite: 0% or more and less than 5%, and with the remainder being bainite,and having:
a dislocation density of 5.0×1015 m more, a solute carbon amount of 0.08 mass % or more and a tensile strength of 1180 MPa or more.