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在Gleeble-1500D热模拟试验机上对19MnB4冷镦钢进行了常温压缩变形试验,应变速率设置为0.01、0.1、1 s~(-1)。研究了19MnB4在常温下塑性变形的流变应力,并分析了应变和应变速率对其的影响机制。结果表明:19MnB4钢具有明显的应变速率敏感性,常温压缩下的屈服强度随着应变速率的增大明显提高。根据实验数据,利用最小二乘法原理拟合得到冷镦钢19MnB4的Johnson-Cook塑性变形本构方程。计算结果和试验结果对比表明,该方程能较好地表达材料在常温下不同应变速率压缩的流变应力变化趋势。
The compression tests of 19MnB4 cold heading steel were carried out at room temperature on a Gleeble-1500D thermal simulator. The strain rate was set to 0.01, 0.1, 1 s -1. The flow stress of plastic deformation of 19MnB4 at room temperature was studied and the mechanism of strain and strain rate was analyzed. The results show that 19MnB4 steel has obvious strain rate sensitivity. The yield strength of the 19MnB4 steel increases obviously with the increase of strain rate. According to the experimental data, Johnson-Cook plastic deformation constitutive equation of 19MnB4 cold heading steel was obtained by the least square method. Comparing the calculated results with the experimental results, it is shown that the equation can well express the trend of the flow stress of materials under different strain rates of compression at normal temperature.