Abstract: Large amount of springback is one of the major problems involved in the hot forming of super-high strength steel sheets. In order to investigate the mechanism of the springback after the hot forming of super-high strength steel sheet metal 22MnB5,the thermo-mechanical properties of the material must be determined. Tensile tests in an elevated temperature range are conducted,aiming at obtaining the thermo-mechanical properties of 22MnB5 sheet metal. The effects of deformation temperature and strain rate on elastic strain and creep strain are examined through hot tensile tests. The influences on springback of deformation temperature and temperature at the end of forming are investigated through isothermal and non-isothermal forming tests. Finite element numerical simulations of hot forming for channel shaped parts are implemented. It can be concluded from the experimental results and numerical results that the heat effect resulting from different cooling rates is the main factor affecting the springback,while creep strain reduces the elastic reversion,thus reducing the springback. Creep strain and heat effect are the main factors influencing the springback.

Key words: creep, finite element method, numerical simulation, super-high strength steel, hot stamping, springback