Investigation of the influence of forming parameters on the springback of hot-stamped hat-shaped parts

The application of hot stamping parts has become a dominant approach to achieve lightweight design and increase crashworthiness performance in the automotive industry. Compared to the cold stamping parts, the main feature of the hot stamped component is its high strength and good size stability. However, recent studies have shown that the springback or size deviation of hot stamped parts caused some assembly problems. This paper aims to investigate the influence of forming parameters on the part’s springback via a hot stamping hat-shaped die. Three different forming parameters with the same blank heating temperature (930°C) were conducted in the study: (1) transfer time 8 sec/die quenching 15 sec (2) transfer time 8 sec/die quenching 8 sec and (3) transfer time 18 sec/die quenching 15 sec. The selected forming parameters are used to evaluate the effect of the before-forming blank temperature and die-opening blank temperature on the springback of the hot stamping parts. The results show that the case 3 with a prolonged transfer time causes a small portion of ferrite phase formation in the hot-stamped part, resulting in the decrease of the tensile strength and a more significant springback is observed.