Study On The Hot Stamping Process Of High Strength Steel Blanks

The application of high strength steel is very important in automotive light weighting industry and promoting passive security. However, with the enhancement of the blank's mechanical strength, its formability is worsened dramatically. It was difficult to apply traditional cold stamping technology into the field of pressing HSS. With the development of metallurgy, new HSS have emerged which are impossible to be shaped by conventional cold forming technology.The hot stamping of martensitic steel blank is a new technology which combine metal thermoplastic forming method with mould quenching principle. Boron steel blank can be quenched and formed simultaneously during the process of hot stamping, which allow complex geometries and high mechanical strength.The Usibor 1500 Martensitic steel from Arcelor U.S. is a typical representative of advanced high strength steels, which's mechanics performance can be greatly enhanced through hot stamping process. On the basis of mechanical tests of this material, physical experiments and numerical simulation of U-shape workpiece under hot stamping process are performed here. Through the thermal mechanical coupling analysis on hot stamping, the distribution and diversification in metal sheet during the process are presented and effect of the initial temperature of blanks, moulds as well as punching velocity are also concluded. A special mould features assembled concave mold and water cooling system is designed and manufactured, by which sets of HSS U-shape workpiece were produced. After examine their dimensions and metallographic phase, the essence of hot stamping technology as well as its feasibility and reliability were proved.