Cr-Co-Mo-Ni齿轮钢的热变形行为及模锻工艺的有限元模拟

在Gleeble-3800热模拟试验机上进行大变形等温压缩试验,研究Cr-Co-Mo-Ni齿轮钢的高温热变形行为和显微组织,分析材料流变应力与变形温度和应变速率的关系,建立热变形过程的本构方程和热加工图.该材料的流变应力随着温度的升高而下降,随应变速率的增加而增加;用双曲正弦函数式可描述其在热变形过程中的流变应力,热变形活化能为487.21kJ·mol-1;热加工图显示的适宜加工区间为温度1000～1100℃,应变速率0.1 ～1s-1.在热模拟试验基础上进行该钢种锻造工艺的有限元模拟,并结合热加工图分析初锻温度和加工道次对于锻件温度和应变速率的影响,得出适宜的模锻工艺参数为初锻温度1000～1100℃,锻造道次15次.

Hot deformation behavior of Cr-Co-Mo-Ni gear steel and finite element simulation of the die forging process

Large strain isothermal compression tests were carried out on a Gleeble-3800 thermal simulator to study the high temperature deformation behavior of Cr-Co-Mo-Ni gear steel.The constitutive equation and hot processing map of the steel were established based on experiment data.The results show that the flow stress decreases with increasing temperature,but increases with increasing strain rate.The flow stress can be described by the constitutive equation in a hyperbolic sine function and the averaged value of activation energy is 487.21 kJ·mol-1.The proper hot working regions shown by the hot processing map are the temperature of 1000-1100 ℃ and the strain rate of 0.1-1 s-1.In addition,the forging processes were simulated by finite element method based on the experiment,the effects of initial forging temperature and passes on the temperature and strain rate of forgings were analyzed,and the proper forging process parameters were obtained which are the initial forging temperature of 1000-1100 ℃ and the forging passes of 15.