模具温度对AZ31B镁合金管材纵连轧成形性的影响

The Influence of Die Temperature on the Formability of AZ31B Magnesium Alloy Tube in Longitudinal Continuous Rolling

镁合金具有比强度高、阻尼及电磁屏蔽性能好等优异的性能被广泛应用于3C、航空航天等高端装备领域。镁合金管材连轧具有三维非线性多场耦合的特征,芯棒及轧辊温度严重影响管材的成形质量。在初轧温度为350℃、应变速率为0.05 s^-1、恒定压下量条件下,对尺寸为Φ50 mm×5 mm×1000 mm镁合金管材进行短流程连轧模拟和实验研究。结果表明:芯棒和轧辊温度对镁合金管材轧制成形性影响显著。芯棒温度和轧辊温度分别为20℃和300℃时,轧后管材表面损伤严重。当温度为20℃时,轧后镁合金管材表面出现微裂纹;当温度为300℃时,轧后管材表面沿轧制方向出现条状凸起。当芯棒和轧辊温度均为150℃时,轧后镁合金管材内外表面光洁度高,且晶粒细小均匀。

Magnesium alloys are widely used in advanced equipment fields such as 3C,aerospace,and other fields owing to their high specific strength,good damping,and good electromagnetic shielding properties.However,the rolling process can refine the as-cast structure while improving production efficiency.Longitudinal rolling of magnesium alloy tube has the characteristics of 3D non-linear multi-field coupling,and the mandrel and roll temperature seriously affect the forming quality of the tube.Under the condition of initial rolling temperature of 350℃,strain rate of 0.05 s^-1 and constant reduction,the simulation and experimental study of short-flow continual mandrel rolling compact(CMRC)ofΦ50 mm×5 mm×1000 mm magnesium alloy tube were carried out.The results show that the mandrel and roll temperature have a significant effect on the roll formability of magnesium alloy tube.When the mandrel temperature and the roll temperature are 20℃and 300℃,respectively,the surface damage of the tube after rolling is severe.When the temperature is 20℃,micro-cracks appear on the surface of the magnesium alloy tube after rolling;when the temperature is 300℃,the surface of the tube after rolling shows strip-like protrusions along the rolling direction.When the mandrel and the roll temperatures are both 150℃,the inner and outer surfaces of the magnesium alloy tube after rolling are high in smoothness and the crystal grains are fine and uniform.