DP (dual-phase) steel is a high-strength steel obtained by critical zone heat treatment or controlled rolling of low carbon steel or low alloy steel. Its structure has a ferrite matrix and about 20% in iron. Composed of island-shaped martensite on the grain boundaries of the solid body, it is also called martensite dual-phase steel. The basic components of dual-phase steel are C and Mn, and sometimes a certain amount of Cr and Mo are added to improve the hardenability.