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1.引言单轴拉伸试验是材料基础力学试验之一,研究它的形变与断裂过程,历来受到人们的重视。关于超高强度钢单轴拉伸的形变规律,一般来说,当外加负荷较小时,材料处在弹性阶段,这时试样形状为圆柱体,应力与应变服从虎克定律。随外加负荷增加,材料进入塑性状态。从屈服至最大负荷这一段,试样仍保持为圆柱体,应力与应变关系服从二段幂乘硬化律。从最大负荷到断裂这一段,试样发生了局部变形,即所谓颈缩现象,
1. INTRODUCTION Uniaxial tension test is one of the basic mechanical tests of materials. It has always been valued by people for its deformation and fracture process. On the uniaxial tensile deformation of ultra-high strength steel, in general, when the external load is small, the material is in the elastic phase, when the sample shape is cylindrical, stress and strain obey Hooke’s law. With additional load increases, the material into the plastic state. From the yield to the maximum load of this period, the sample remained as a cylinder, stress and strain relationship obeys the second power multiplication hardening law. From the maximum load to the fracture of this section, the sample had a local deformation, the so-called necking phenomenon,