Patent ID: 9194015
Filing Date: 2015-11-24
Classification: C21D,C22C

Abstract:
1. A cold rolled dual phase steel sheet with good bake-hardening properties containing (in terms of percent by mass): C: no less than 0.06% and less than 0.25%; Si+Al: 0.5 to 3%; Mn: 0.5 to 3%; P: no less than 0.03% and no more than 0.15%; and S: no more than 0% and no more than 0.02%, wherein the steel sheet consists of (in terms of space factor): bainite: more than 80%,and ratained austenite: at most 20%, wherein the steel sheet contains no ferrite other than the ferrite in the bainite, no pearlite and no martensite, and wherein a 2% pre-strain places the steel sheet under a first stress; after heating the steel sheet at 170° C. for 20 minutes the 2% pre-strain places the steel sheet under a second stress; and the difference between the second stress and the first stress is larger than 100 MPa.