Phase transformation and heat conduction interaction analysis and sensitivity analysis to temperature in quenching process of steel considering variability in its chemical composition

Abstract

As one of the approaches to problem of variability in the thermal deformation of steel products after rapid cooling in the quenching process, a new computational method to evaluate the sensitivity to temperature concerning chemical composition of steel is described in this paper. The phase transformation and heat conduction interaction problems were solved by the finite element method. To calculate the sensitivity, parameterization of all necessary quantities was carried out not only for heat conduction analysis but also for prediction of phase transformation using time-temperature-transformation diagram and phase fraction. The sensitivity to the temperature through each parameter was calculated with respect to chemical composition within the range of variability defined for JIS SCr420 steel. One of the findings in this study lies in the significant differences in temperature, strain and deformation after the appearance of bainite phase due to small fluctuation in chemical composition. Moreover, the above sensitivity values were calculated as a function of time. It was found that the influences of Si on temperature through density, thermal conductivity and phase fraction were larger than those before bainite transformation. After the appearance of bainite, the influence of Si through phase fraction decreased, but the sensitivities concerning Mn and Cr increased.

Keywords

• steel
• quenching
• chemical composition
• sensitivity analysis
• heat conduction
• phase transformation