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确定金属板成形性可以应用如下材料参数:应变硬化指数n,应变速度敏感性指数m和塑性应变比r。因为它们影响应变的分布及缩颈扩展的阻力,对金属板成形至关重要。基于成形性和应变硬化行为(n、m、r)以及材料冶金学性能之间的关系,金属板的成形性可以通过工艺参数的控制得到改善。文中阐述了n、m值对单轴塑性流动的影响,以及平面应变状态塑性失稳判据。并提出了通过常规拉力试验获得失稳应力的作图方法.应用n,m、r值将铝、黄铜、软钢的成形性作了比较;指出体心立方晶型(如钢)更多地受到择优取向的影响。在面心立方晶型中(如铝、黄铜)晶粒尺寸的影响则不可忽视。
Determining sheet metal formability The following material parameters can be applied: the strain hardening index n, the strain rate sensitivity index m and the plastic strain ratio r. Because they affect the distribution of strain and the resistance of necking expansion, it is crucial for sheet metal forming. Based on the relationship between formability and strain hardening behavior (n, m, r) and material metallurgy properties, sheet metal formability can be improved through the control of process parameters. In this paper, the influence of n and m on the uniaxial plastic flow and the plastic instability criterion of plane strain state are expounded. And put forward the drawing method to obtain the instability stress through the conventional tensile test.Comparing the formability of aluminum, brass and mild steel with the values of n, m and r, it is pointed out that more body-centered cubic (such as steel) Affected by the preferred orientation. In the face-centered cubic crystal (such as aluminum, brass) the impact of grain size can not be ignored.