Effect of Martensite Volume Fraction on Deformation Dislocation Structure and Fracture for Hot Rolled Dual-Phase Steel

Effect of martensite volume fraction on deformation dislocation structure and fracture for hot rolled dual-phase steel of the same composition was studied by using SEM and TEM.The results show that effect of martensite volume fraction on deformation dislocation structure of DP steel is little when martensite volume fraction is between 20% and 30%.And martensite would appear both region of high dislocation density and region of low dislocation density after deformation.Furthermore,the micropore in DP steel would change into microcrack when martensite volume fraction reached 30%.Meanwhile necking appeared early.So when martensite volume fraction was 20%,forming property of DP steel was better than the DP steel whose martensite volume fraction was 30%.