A 780MPA COLD-ROLLED DUEL-PHASE STRIP STEEL AND METHOD FOR MANUFACTURING THE SAME

摘要

Provided is a 780 MPa class cold rolled dual-phase strip steel having a microstructure of a fine equiaxial ferrite matrix and martensite islands uniformly distributed on the ferrite matrix, and having the following chemical elements in weight percent contents: C: 0.06-0.1%; Si=0.28%; Mn: 1.8-2.3%; Cr: 0.1-0.4%; Mo which is not added when Cr=0.3% and Mo=0.3-Cr when Cr<0.3%; Al: 0.015-0.05%; at least one of Nb and Ti, with Nb+Ti falling within the range of 0.02-0.05%; and the balance being Fe and other inevitable impurities. Accordingly, also provided is a method for manufacturing the 780 MPa class cold rolled dual-phase strip steel. The 780 MPa class cold rolled dual-phase strip steel has relatively high strength, good elongation, good ability to phosphorise, and relatively small anisotropy in mechanical properties.