本文对Hollomon关系式所定义的应变硬化指数（n值）的力学本质，进行了不同拉伸控制模式下的解析，通过单向拉伸实验分析了不同拉伸速率对n值的影响。研究表明：1）应变硬化指数（n值）不是常数，而是与控制模式有关的变量；2）由于多晶体金属材料塑性变形过程的时间性特点，提高拉伸速率会降低n值；3）拉伸在均匀塑性变形阶段推荐使用应变速率控制模式；由于是静载荷拉伸试验，采用较低的拉伸速率使得拉伸各项特征值更接近真实值。
The effect of different tensile control model on strain hardening exponent(n-value) was analyzed on the basis of Hollomon formula. The effect of tensile rate on n-value was also discussed by simple tensile test. It is indicated that from the study: 1)the strain hardening exponent is not a constant but a variable being relevant with the control model; 2) Since plastic deformation of polycrystalline metal is time-dependent, the n-value decreases with increasing the tensile rate . 3) It is suggested to use the strain rate control model at tensile step of uniform plastic deformation. As the tensile test is static loading test, it’s more close to the true value for low tensile rate.
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