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本文基于粘—塑性流动的力学状态方程σ=kε~nε’~m,根据材料恒速超塑拉伸的真应力—应变曲线所具有的σ_(max)下的应变量ε_U与m和n的关系和均匀变形阶段的特性,利用回归法对应于似均匀变形阶段在lnσ-ε曲线上得到的近似直线的斜率S,提出了解方程式组:ε_U=n/m和S=αn-m来决定m和n值的新方法。并称这种方法为曲线斜率法。式中α为在不同情况下按给定不同的同归区间取的不同常数。用此法得到GCr6钢的m和n值分别为0.37和0.13(在720℃和初始应变速率为4×10~(-4)s秒c~(-1)条件下);得到Z_n-22％Al的m和n值分别为0.57和0.054(在250℃和初始应变速率为4.3×10~(-3)条件下)。
Based on the mechanical equation of state of viscous-plastic flow σ = kε ~ nε ’~ m, according to the true stress-strain curve of material constant speed superplastic tension, the strain amount ε_U and m and n Relationship and uniform deformation stage characteristics, the regression method corresponding to the uniform deformation stage lnσ-ε curve approximation of the slope S of the line, the solution to the equation set: ε_U = n / m and S = αn-m to determine the m And n value of the new method. Called this method for the curve slope method. In the formula, α is the different constant taken by different homologous interval in different situations. The m and n values of GCr6 steel obtained by this method are 0.37 and 0.13 respectively (under the conditions of 720 ℃ and initial strain rate of 4 × 10 -4 s s -1 c -1); Z_n-22% The m and n values for Al are 0.57 and 0.054, respectively (at 250 ° C and an initial strain rate of 4.3 × 10 -3).