中文摘要：

基于Gleeble-1500型热模拟试验机进行热压缩试验,通过对试验数据进行线性回归分析推导出了铸态42CrMo钢热压缩变形的本构方程,同时探讨了热压缩变形参数对显微组织的影响。结果表明：在相同的变形温度（850～1 150℃）下,该钢变形后的显微组织随着应变速率的增大逐渐变细,在5s-1时达到最细;在相同的应变速率（0.1～5s-1）下,显微组织随着变形温度的升高逐渐变细后再粗化,在1 050℃时马氏体板条最细;在相同的应变速率（1～5s-1）和变形温度（900～1 050℃）下,随着变形量的增加,再结晶晶粒尺寸均得到了显著细化;在温度为1 050℃、应变速率为5s-1、应变为0.6时热压缩后晶粒的细化效果最为显著。

英文摘要：

Based on the thermal compression experiment on Gleeble-1500 thermal simulation machine,the constitutive equation of as-cast 42CrMo steel during hot compression deformation was derived through linear regression analysis for the test dadas.The effects of hot compression deformation parameters on microstructure were discussed.The results show that at the same deformation temperature（850-1 150 ℃）,the grains size of the steel after deformation decreased with the increase of the strain rate,and it reached the minimum at the strain rate of 5 s-1.At the same strain rate（0.1-5 s-1）,the microstructure decreased gradually,then increased with the increase of the deformation temperature,and the martensite lath reached the minimum at 1 050 ℃.The grains size decreased sighnificantly with the increase of the deformation at the same strain rate（1-5 s-1） and deformation temperature（900-1 050 ℃）.The best refining effect could be obtained after recrystallization could be obtained at temperature of 1 050 ℃,strain rate of 5 s-1 and strain of 0.6.