Prediction of necking & thinning behaviour during hot stamping conditions of 22MnB5 steel

Hot stamping is a high-temperature forming operation in which the blank is heated to austenitization temperature, and subsequent forming and quenching operations are done simultaneously. In the current research, forming limits were determined using a thickness gradient-based criterion. For this purpose, the tensile and plane strain mode of deformation were considered. The study was carried out in a wide range of temperatures, viz. 750 °C,800 °C and 850 °C at a constant strain rate of 0.01/s. The experiments were carried out in the thermomechanical simulator (Gleeble-3800), and subsequent measurement of thinning evolution for all the deformed specimens were carried out. It was observed that with the increase in temperature, thickness reduction was less and the distribution of thickness was uniform in tensile specimens and at the point of necking thickness gradient ratio is below 0.92 at various temperatures.