温度和背压方式对等通道转角挤压过程的影响

建立了用于分析等通道转角挤压过程的热力耦合有限元模型。通过对纯钛等通道转角挤压过程的数值模拟,获得了模具及试件内部的应力、应变和温度分布。研究结果表明,等通道挤压过程中试件温度分布不均匀,在模具转角剪切部位温度最高且存在明显的温度梯度。在较高的温度条件下进行挤压,有利于降低成形压力和获得较大的变形量;接触摩擦的存在导致模具受力状况恶化及试件变形的不均匀;而带背压的挤压方式可以在有效地增加试件变形量和变形均匀性的同时降低材料产生破坏的可能性。

Effects of Temperature and Back Pressure Type on Equal Channel Angular Extrusion Process

The thermo-mechanical coupling finite element mode was built to investigate the effects of temperature and back pressure type on material behavior of the pure titanium during the equal channel angular extrusion process.The distribution of temperature,strain and stress of die and billet were obtained.Results indicate that the distribution of temperature is not uniform during the ECAE process;there are abrupt increases in the temperature within the billet at the point where it passes through the shearing plane.The large strain level of billet can be obtained under high temperature conditions,while the existence of friction decreases uniformity of strain distribution.Finite element analysis shows that hydrostatic stress state has important effect on the result.The ductility of material can be improved in high hydrostatic stress state.And the back pressure applied to the ECAE can greatly increase the strain level accumulation without reducing the uniformity of the strain distribution.