挤压态TiAl合金热变形行为及热加工图研究

Study on hot deformation behavior and hot processing map of as-extruded TiAl alloy

针对TiAl合金热塑性变形难的问题,通过MMS-200型热模拟试验机研究了挤压态Ti-47Al-2Cr-2Nb合金在变形温度为1000~1300℃、应变速率为0.001~1 s^(-1)、工程应变为60%条件下的热变形行为。通过Arrhenius函数模型建立了该合金基于应变补偿的本构方程;基于动态材料模型建立了合金在工程应变为60%时的热加工图。结果表明,该合金具有正应变速率敏感性和负温度敏感性;通过建立的热加工图发现理想的变形参数为1100~1150℃、0.001~0.05 s^(-1)和1200~1300℃、0.001~0.01 s^(-1),突破了传统TiAl合金只能在高温低应变速率条件下变形的认知,发现在0.01和0.1 s^(-1)高应变速率下通过合适的成形温度匹配,该合金仍可以获得较好的成形性能。

Aiming at the difficulty of thermoplastic deformation of TiAl alloy,the thermal deformation behavior of as-extruded Ti-47Al-2Cr-2Nb alloy at deformation temperature of 1000-1300℃,strain rate of 0.001-1 s^(-1) and engineering strain of 60%was studied by using MMS-200 thermal simulator.The constitutive equation of the alloy based on strain compensation was derived by Arrhenius function model.Based on the dynamic material model,the hot processing maps of the alloy with engineering strain of 60%were established.The results show that the alloy has positive strain rate sensitivity and negative temperature sensitivity.It is found that the ideal deformation parameters are 1100-1150℃,0.001-0.05 s^(-1) and 1200-1300℃,0.001-0.01 s^(-1),which breaks through the traditional recognition that TiAl alloy can only deform at high temperature and low strain rate.It is found that the alloy can still obtain better formability by suitable forming temperature matching with high strain rates of 0.01 and 0.1 s^(-1).