Effects of different process parameters on mechanical properties and microstructures of hot stamping boron steel

Abstract

Hot stamping process has been increasingly used to produce automotive parts with ultra-high-strength property. Thus, increasing the crashworthiness of new generation vehicles and reducing car body weight could be simultaneously obtained. Taking boron steel B1500HS as the research object, this paper built a set of hot stamping experiment equipment that could monitor the temperature of sheet metal and die in real time. The initial forming temperature, contacting pressure, and pressure holding time in hot stamping process were examined under the condition of continuous hot stamping when the die temperature got into dynamic stability. The microstructures and mechanical properties including tensile strength, elongation, and hardness of stamped blank were used as quality evaluation indexes. For B1500HS boron steel sheets with the thickness of 1.2 mm, the optimal process parameter combination of hot stamping process comes true when the initial forming temperature is 800 °C, the contacting pressure is 20 MPa, and the pressure holding time is 10 s. The high-quality hot stamping parts with compact martensite phase could be finally obtained at the tensile strength of 1495 MPa, elongation of 7%, and hardness of 510 HV.