Effect of Microstructure on Mechanical Properties of Hot Rolled Bainitic Dual-phase Steel

In this work the bainitic dual-phase steel with combined high strength and good toughness had been achieved through ultra-fast cooling after hot rolling.The effect of microstructure on hole expansion performance and mechanical properties had been studied.The resulted steel is mainly composed of ferrite and bainite,with tensile strength of 501 MPa and total elongation of 34%.The good mechanical property of steel is related to bainite.Excess hard phase bainite and pearlite deteriorate hole expansion performance,however,large fraction of polygonal and quasi polygonal ferrite can improve the elongation and hole expansion.