| With the rapid development of computer technology and the increasing requirements of hardening quality, the computer simulation of quenching process has been attracted more and more attentions and becomes indispensably important means for the present quenching process research and technological design. The quenching process simulation of large forgings has a very important significance for the work piece performance improving, the reduction of distorts and cracks, the quality controlling and guaranteeing.In this paper, a cooling rate controlled experiment device has been designed and manufactured. Using this experiment device, various kinds of heat treatment experiments can be carried out conveniently such as air cooling, gas cooling, spray cooling, water quenching and oil quenching. Thus a cooling rate controllable experiment platform is provided for various cooling experiments of shaft and plate workpiece. Air cooling and spray cooling experiments are carried out with this experiment device. Based on the experiment results, the general convective heat-exchange coefficient is educed by using the method of non-linear estimation. Consequently the problem is solved that the influence factors are complicated and the heat transfer coefficient is difficult to figure out. Completely considering the temperature field, the microstructure field and the internal stress field of the quenching test-piece, a FEM model of quenching process is built based on the FEM (Finite Element Method) software DEFORM. The model is validated by experiments.The FEM study transforms the research of quenching process from qualitative analysis to quantitative analysis. The research of relationships among the temperature field, the microstructure field and internal stress field for large section shaft workpiece, harden thickness and the microstructure distribution and stress field prediction have a important practice instruction significance.Also it can provide scientific ground for the quenching process craft design.
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