Influence of Die Temperature on Microstructure and Strength-Toughness of B1500HS Steel

Abstract

In order to optimize the strength-toughness matching of auto body components. Taking B1500HS steel as the research object. The influence of die temperature on the microstructure and properties was studied by hot stamping tests of flat die, mechanical properties tests and microstructure observation tests. The study shows that the microstructure and properties of B1500HS is not sensitive to die temperature below 250°C. When the die temperature is 20–250°C, the tensile strength of B1500HS is above 1400 MPa, while the plastic-toughness is poor; When the die temperature is above 300°C, B1500HS steel begins to generate martensite-bainite phase. As the die temperature increases from 300°C to 550°C, the strength and hardness of B1500HS decrease significantly, while the plastic and toughness have the opposite trend. When the die temperature in 300°C, B1500HS has good strength-toughness. The tensile strength, percentage elongation after fracture, Vickers hardness, and impact toughness values are 1308.26 MPa, 8.18%, 436Hv, and 800.41 KJ·m–2 respectively.