22MnB5超高强钢板热成形中的回弹机理分析

Analysis of Mechanism of Springback in 22MnB5 Super-high Strength Steel Forming

回弹是影响热冲压件形状精度的主要因素,为研究影响22MnB5超高强钢板热冲压成形中回弹的因素,在不同温度下对22MnB5高强钢板进行拉伸试验,考察了变形温度和应变速率对弹性应变和蠕变应变的影响,获得其热力学性能。通过等温度和非等试验考察了变形温度、热成形终了温度和压边对热成形后回弹的影响。采用有限元法对槽形件非等温热成形过程进行了数值模拟。从试验结果和模拟结果可知,热效应是引起回弹的主要因素,蠕变应变减少了热成形后的回弹量。蠕变应变和热效应是影响热成形中回弹的主要因素。

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.