扩散控制超塑性拉伸断面均匀收缩的临界应变速率
Critical Strain Rate of the Uniform Deformation in Cross Section at Diffusion Dominated Superplastic Tensile Test
张诗昌, 罗 敏, 杨 倩 , 陈 伟
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作者单位：武汉科技大学
中文关键字：超塑性拉伸 晶界扩散 断面均匀变形
英文关键字：superplastic tensile ; grain boundary diffusion; cross section uniform deformation
中文摘要：引入了一个衡量超塑性拉伸断面收缩均匀性的特征参数λ，在假设变形以扩散为主的条件下，导出了λ的表达式。在令λ=0时，得到断面均匀收缩的临界应变速率 。 与扩散系数和应变量成正比，与试样原始截面积成反比。对AZ31镁合金超塑性拉伸特征参数λ值的测定结果表明：当应变速率越接近于临界应变速率时,λ越小，试样越接近均匀变形。
英文摘要：A parameter named λ was put forwarded and an equation was deduced to characterize the uniform deformation of superplastic tensile test under the conditions of diffusion dominated deformation. By solving the equation at λ=0, a critical strain rate of uniform deformation was got. It was shown that is direct proportion to strain and diffusion coefficient and inversely proportion to the cross section area of undeformed specimens. The results of the tested λ of AZ31 magnesium alloy under superplastic tensile showed that λ is becoming significant small and cross section of the specimen tends to uniform deformation when strain rate is at the near of .