Abstract: Hot compression tests of DIN 1. 2738 die steel for plastic (/% ：0. 35 ~0. 46C,0, 20 ~ 0.40Si, 1.30 ~ 1.60Mn,L 80 ~2.20Cr,0.90 ~ 1.20Ni,0.15 ~0.23Mo) are carried out by a Gleeble-3800 thermal-mechanical simulator to get stress-strain curves of steel at 850 ~ 1250℃  with strain rate 0. 01 ~30 s^-1. Based on the hot deformation data,the peak stresses of steel, the strain-compensated constitutive equation and hot processing maps are established. Suitable hot deformation parameters are also identified by analyzing the processing maps. The results show that the hot deformation activation energy of DIN 1.2738 steel is 354. 21 kj/mol. Adopting the established strain-compensated constitutive equation, the flow curve can be predicted accurately. The suitable hot deformation parameters for DIN 1.2738 steel are： (1) temperature between 950 ℃ and 1150 ℃，strain rate between 0.01 s^-1 and 0.7 s^-1 ； (2) temperature between 1170℃. and 1200 ℃, strain rate between 0. 01 s^-1 and 1 s^-1.

Key words:  , DIN 1.2738 Die Steel for Plastic, Hot Deformation, Constitutive Equation, Processing Maps

摘要： 采用Gleeble-3800热模拟试验机进行了DIN 1.2738塑料模具钢（/%:0.35～0.46C,0.20-0.40Si,1.30～1.60Mn,1.80～2.20Cr,0.90～1.20Ni,0.15～0.23Mo）的热压缩实验,获得了该钢在850～1250℃、应变速率在0.01～30的应力-应变曲线。基于得到的热变形数据,建立了该钢的峰值应力以及应变补偿的热变形本构方程和热加工图,并结合热加工图的结果分析了该钢合理的热加工参数范围。结果表明,DIN 1.2738钢的热变激活能为354.21 kJ/mol,利用建立的应变补偿的双曲正弦本构方程可对塑料模具钢的热变形曲线进行准确预测,通过加工图的分析可得DIN 1.2738塑料模具钢的最佳的热变形工艺参数范围为:（1）温度950～1 150℃,应变速率0.01～0.7 s^-1;（2）温度1170～1200℃,应变速率0.01～1 s^-1。

关键词: DIN 1.2738塑料模具钢, 热变形, 本构方程, 加工图