Based on exploring quenching mechanism,three types of quenching critical cooling rate models of medium-carbon steel and low-carbon steel and low-alloy construction steel were established,as modified Maynier model,Eldis model and isothermal curve model,respectively. During construction process,regression analysis and Newton interpolation method were used for higher calculated precision. Through comparing and analyzing,the superior one was selected to evaluate the full hardening thickness after quenching. According to hardness analyzing,the deviation between predicted hardness distribution and the experimental value is within 6%.
FU Tian-liangWANG Ri-qingWANG Zhao-dongWANG Guo-dongWANG Ming-tao
After water cooling,there is a big temperature difference between the center and the surface of strip,which leads to the heat transfer from the center to the surface,and the surface temperature can rise in a short time.The finite element method was used to simulate the phenomena of re-reddening on the surface of strip and to analyze the temperature field of hot rolled strip during laminar cooling,and the periodical variation curve of the cooling rate was obtained during water cooling and subsequent re-reddening.The results show that the critical line of the cooling rate is at 1/3 of the half-thickness from the strip surface.The regression model of the relation of re-reddening temperature,time,and distance from the surface was obtained in the re-reddening region.Re-reddening regularity on the surface of strip under the condition of different thickness and cooling rate was also studied.
