20CrMnTiH钢的热变形物理模型及三维加工图

随着精密成形技术的发展,对热锻工艺的要求越来越严格,采用建立材料的物理模型及热加工图这一方法来优化最佳工艺条件,为实现产品的质量精确控制提供了科学保障。通过Gleeble-3800热模拟试验机对20Cr Mn Ti H钢在变形温度为850~1 150℃,应变速率为0.01~10 s~(-1)条件下进行等温热压缩试验,研究了20Cr Mn Ti H钢的热压缩变形特性,采用Zener-Hollomon参数法建立了20Cr Mn Ti H钢高温塑性变形的物理模型;并以热压缩试验为基础,绘制了20Cr Mn Ti H钢的三维热加工图并进行分析,确定了该钢的最佳热成形工艺参数。通过流变曲线可以看出,20Cr Mn Ti H钢在热成形过程中发生了明显的动态回复与动态再结晶,流变应力随应变速率的增加而增加,随变形温度的升高而降低;由热加工图分析得到了该钢在试验参数范围内较优的热加工工艺参数,加工温度为900~1 025℃,应变速率为0.01~0.2 s~(-1)。

Physical model and 3D thermal processing map of hot deformation of 20CrMnTiH steel

With the development of precision processing technology,the requirement for hot forging process was more and more strict. The optimum process was obtained through the methods of establishing physical model of the material and drawing hot processing map to guarantee the accurate control of the products'quality. Hot compression tests of 20CrMnTiH steel were carried out at the temperature range of 850-1150℃and at the strain rate range of 0.01-10 s-1 through the thermal simulated test machine of Gleeble-3800 to study the hot compression behavior. The physical model of the plastic deformation of the tested 20CrMnTiH steel at high temperature range was obtained by using Zener-Hollo-mon parameter method. According to the experimental results,the three dimensional hot processing maps based on the dynamic materials modeling were drawn and analyzed,and the optimal parameters of the thermal processing were deter-mined. The rheological curve showed that the dynamic recovering and dynamic recrystallization obviously occurred dur-ing hot compression of 20CrMnTiH steel. The rheological stress increased with the increasing of strain rate and decreased with increased deformation temperature. According to the thermal processing map,the optimum processing parameters were obtained at strain rate range of 0.01-0.2 s-1 and deformation temperature range between 900 to 1025℃.