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 Uniform Deformation in Cross Section at Diffusion Dominated Superplastic Tensile Test

作　　者：张诗昌[1] 罗敏[1] 杨倩[1] 陈伟[1] 

机构地区：[1]武汉科技大学材料与冶金学院,湖北武汉430081

出　　处：《热加工工艺》2012年第11期19-21,共3页Hot Working Technology

基　　金：武汉科技大学绿色制造与节能减排科技研究中心资助项目(B1211)

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。令λ=0时,得到断面均匀收缩的临界应变速率ε觶cri。ε觶cri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,λ越小,试样越接近均匀变形。A parameter named λ was put forward 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 ε^·cri of uniform deformation was got ten.The results show that ε^·cri 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 alloy under superplastic tensile show that λ is becoming significant small and the cross section of the specimen tends to be uniform deformation when strain rate is near εcri.

关 键 词：超塑性拉伸 晶界扩散 断面均匀变形 

分 类 号：TG113.2[金属学及工艺—物理冶金]