Abstract: Measured friction coefficient of DP780 dual phase HSS under  different temperatures，a novel variable friction coefficient model was 
established，and the formability during room temperature cold stamping   was researched based on thermal-mechanics coupling and variable friction 
coefficients.The results show that temperature is increased obviously in  some areas of sheet metal in heat variable（HV） groups，and comparing the 
same places with compared groups，the thinning ratio is smaller，not easy  to crack，better ductility are showed.From spring-back displacement 
contour，values in HV groups  are smaller than the measured values in  stamping experiments.However values in compared groups are bigger，and 
compared with the experimental measured values，the errors of HV groups  are only 27.8%   of compared groups，and are agreed with stamping 
experiments better.

Key words: variable friction coefficient, flow stress, thermal-mechanics coupling, high strength steel（HSS）

摘要： 测定了DP780高强度双相钢在不同温度下的摩擦因数，建立了变摩擦因数模型,研究了热-力耦合和变摩擦因数对室温冷成形的影响。结果显示，热变组仿真分析
部分区域温度明显升高，相比参照组相同区域，板料减薄程度更小，不易开裂，表现出更好的延展性。从回弹偏移量看，热变组的值比冲压实验测量值偏小，而参照组的值偏大，且相比冲压实验测量值的误差，热变组仅为参照组的27.8%，与冲压实验符合度更好。

关键词: 变摩擦因数, 流变应力, 热-力耦合, 高强钢