300M钢热扭转变形条件下的变形行为研究

Deformation behaviors of 300M steel under hot torsion

为了更好地揭示300M钢热锻成形过程中的变形机制,通过热扭转实验研究了300M钢在变形温度范围为900~1150℃、等效应变速率范围为0.0115~1.15 s^-1条件下的流动行为。根据300M钢热扭转变形的流动应力曲线,分别建立了300M钢的本构模型和临界应变模型。分别将300M钢在剪切应力和压应力状态下的特征应力和特征应变进行对比发现,300M钢的流动行为受到应力状态、变形温度及应变速率的耦合影响。当材料的变形抗力较高时,其流动行为明显受到应力状态的影响。当变形抗力较低时,其流动行为几乎与材料的受力状态无关。此外,300M钢动态再结晶过程发生的时刻对变形温度和应变速率的敏感性明显不同。

The flow behaviors of 300 M steel at deformation temperature of 900-1150 ℃ and equivalent strain rate of 0. 0115-1. 15 s^-1 were investigated by hot torsion experiments to better reveal the deformation mechanism of 300 M steel during the hot forging process. According to the flow stress curves of 300 M steel during thermal torsional deformation,the constitutive model and critical strain model of300 M steel were established respectively. By comparing the characteristic stress and characteristic strain of 300 M steel under shear stress and compression stress respectively,it is found that the flow behaviors of 300 M steel are affected by the coupling effects of stress states,deformation temperature and strain rate. The flow behaviors are obviously affected by the stress state when the deformation resistance of material is high. The flow behavior is almost independent of stress state when the deformation resistance is low. In addition,the tensitivity of occurrence time of 300 M steel dynamic recrystallization process to deformation temperature and strain rate is significantly different.