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

Abstract

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.

Hot tensile and expansion tests of Ductibor®1000 steel

“…One is referred as the complete DIC method, since both the radius of curvature and the thickness are evaluated based on data from DIC. The other, based on the method using laser profilometer, uses the evolution of the dome height extracted from DIC data and equations (2)(3)(4). Finally, the results obtained from a tensile test performed on a Gleeble machine using a DIC system are also discussed.…”

“…The hot stamping process allows to produce parts with these quenchable steels, as described in detailed in [1,2,3]. It consists of an austenization step at high temperature follow by simultaneous forming and quenching steps in a press to obtain high tailored properties [4]. Some devices were developed to perform tests over the temperature range in the austenitic state, mainly to evaluate the forming limit curve (FLC).…”