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采用等应变速率拉伸法研究了温度和应变速率对5A90合金超塑性力学性能的影响。结果表明:5A90铝合金最佳变形温度是400℃,在此温度下,不同应变速率条件下,可以获得较大的伸长率,最大伸长率为193.6%;在变形温度为375℃~500℃时,应变速率对5A90铝合金的流变应力及抗拉强度有显著影响,流变应力及抗拉强度随应变速率升高而增大。在同一应变速率下,5A90铝合金流变应力水平随着变形温度的提高而降低。另外,基于Backofen本构方程,对5A90铝合金在不同温度状态下的强化规律进行了分析,结果表明,随变形温度逐渐升高,应变速率敏感性指数先减小后增大,最后得到5A90铝合金最佳超塑性参数为:T=400℃,ε=0.0005s-1。
The effect of temperature and strain rate on the superplasticity of 5A90 alloy was investigated by constant strain rate tensile test. The results show that the optimum deformation temperature of 5A90 aluminum alloy is 400 ℃. Under this temperature, the elongation at a high strain rate of 193.6% can be obtained under different strain rates. When the deformation temperature is 375 ℃ ~ 500 ℃, the strain rate has a significant effect on the flow stress and tensile strength of 5A90 aluminum alloy, and the flow stress and tensile strength increase with the increase of strain rate. At the same strain rate, the flow stress level of 5A90 aluminum alloy decreases with the increase of deformation temperature. In addition, based on the Backofen constitutive equation, the strengthening rules of 5A90 aluminum alloy at different temperatures were analyzed. The results show that with the deformation temperature increasing, the strain rate sensitivity index decreases first and then increases, finally the 5A90 aluminum The optimum superplastic parameters of the alloy are as follows: T = 400 ℃, ε = 0.0005s-1.