Effect of Heating and Mold Temperature on the Mechanical Properties and Microstructure of B1500HS Boron Steel

Abstract

Abstract To know the effect of the heating temperature and the temperature of mold surface on the mechanical properties and microstructure of B1500HS steel, and supply some practical guides for the components with the distributed microstructure and mechanical properties, B1500HS steel sheets, heated at different austenitization temperatures (870°C, 900°C, 930°C, and 960°C), were formed in hot stamping tools with the different mold temperatures (100°C, 200°C, 300°C, and 400°C). The strength of hot stamping parts was tested by the uniaxial tensile experiment. Moreover, the microstructure, fractography, and micro-hardness of hot stamping parts were measured to evaluate the effect of austenitization temperature and mold temperature on the microstructure and mechanical performance of UHSS steel. The results show that when the heating temperature is 900°C or above, the original microstructure of B1500HS steel can be fully austenitized. Variation of austenitization temperature in the range of 900°C ∼ 960°C has no obvious effect on the mechanical properties of hot stamping parts cooled at the same mold temperature. The mold temperature has a significant effect on the mechanical properties; the structural components with distributed properties can be manufactured by controlling the mold temperature. The austenitization and mold temperatures have no obvious effect on the elongation of parts except the part with the subcritical quenching. The austenitization temperature of 900°C and mold temperature of 100°C are the better parameters of hot stamping for the parts of B1500HS steel required with higher hardness and strength.