本文从增量理论出发,由塑性流动法则,具体导出了Mises-Mises、Mises-Tresca、Tresca-Tresca 型应力-应变率关系。通过热弹塑性蠕变有限元公式的推导,编制了轴对称热蠕变计算的有限元程序,并针对中速四冲程柴油机排气门在高温下的变形,进行了非线性有限元蠕变分析。比较计算结果和实测结果,两者吻合良好。改用4Cr14Ni14W2Mo 钢后,未再出现任何问题。蠕变变形约为0.1mm,符合工程实际要求。 Based on the incremental theory, this paper deduces the stress-strain relationship of Mises-Mises, Mises-Tresca and Tresca-Tresca by the plastic flow rule. Based on the derivation of finite element formula of thermo-elastic-plastic creep, a finite element program of axial symmetry thermal creep was developed. According to the deformation of medium-speed four-stroke diesel exhaust valve at high temperature, nonlinear finite element creep analysis . Comparing the calculation results with the measured results, the two agree well. Switch to 4Cr14Ni14W2Mo steel, no longer any problems. Creep deformation of about 0.1mm, in line with the actual project requirements.