Research and Application of Hot Stamping Process for High Strength Steel Zinc-Based Coated Sheet

Abstract

High-strength steel hot-formed parts are widely used as safety protection parts for automobiles due to their ultra-high strength (1500( -2000. In order to prevent the oxidation and decarburization of traditional high-strength steel sheets during the heating process of hot forming, and at the same time enhance the corrosion resistance of hot-formed parts, galvanized high-strength steel sheets have been applied. The hot forming process of galvanized high-strength steel plate is studied, the mechanism of LMIE crack generation is analyzed, and the hot-forming process route suitable for galvanized high-strength steel plate is formulated. The key process parameters in the hot stamping process of zinc-based plated sheets, namely heating temperature, holding time, effective range and effect of forming temperature, are studied. Short-term heating, pre-cooling forming, shortening the holding time of the sheet, and then reducing the temperature of the sheet to a certain extent by a specific method before forming, the results show that when the forming temperature is low (700 °C), the matrix basically has no cracks. The reduction of the forming temperature is beneficial to the elimination of liquid zinc in the coating, thereby preventing the occurrence of LMIE phenomenon. In addition, when the forming temperature is low, the matrix phase transition temperature range becomes narrow, and the rate of forming cooling is required to be higher. The new generation of zinc-based coated sheets can improve the low temperature hardenability, which is beneficial to the pre-cooling low temperature forming process, which can be regarded as the future direction.