Study on the warm air bending of NM400TP wear-resistant steel sheets heated by online floating contact heating module

Abstract To address the challenge posed by the reduced cold formability of high-strength steel sheets in industrial applications, a novel warm air bending method utilizing an online local contact heating module was investigated. NM400TP high strength low alloy wear-resistant steel sheets were used in experiment and numerical simulation to verify the bending process. A thermo-mechanical coupled model, taking into account the material heterogeneity, was constructed to predict the bending outcomes under various conditions of temperatures and forming speeds. The results proved the validation of the new method in improving the bendability of NM400TP plates, and the model can reveal the heat transfer processes, heterogeneous deformation and fracture characteristics during warm air bending. In comparison to conventional cold air bending, warm air bending conditions with a stamping speed of 1000 mm min −1 and a temperature of 350 °C promoted 54% increase in the bending limit angle and a remarkable reduction in the forming load.