structure and stress field of 0.21C- 1.03Cr-0.20Mo-0.03Nb gear steel cylinder in quenching process has been carried out by using FEM software MSC. Marc
combined with thermal elastic and plastic models and compiled sub programme. The results showed that the internal stress produced in quenching process promoted martensite transformation
in martensite phase transformation conditions the structure stress surpassed thermal stress led to residual stress in quenched piece presented structure stress distribution. Comparison between calculated value and measured value indicated that the calculated results of quenching stress simulation will be more precise with considering interactions between transformation and stress.