平板の油焼入れによる機械構造用鋼の変態塑性係数の同定と熱処理変形予測の高精度化

抄録

To improve the prediction accuracy of oil quenching distortion, the transformation plasticity coefficient was determined by oil quenching experiment on the steel sheet and numerical simulations. The cooling curve of the steel sheet during oil quenching and the deflection after quenching were measured under three experimental conditions. In the first condition, austenitic stainless steel sheet was quenched into cold quenching oil for confirmation of the validation of the temperature prediction results by the numerical simulation. In the second condition, chromium molybdenum steel sheet was quenched into cold quenching oil for confirmation of the validation of the latent heat predicted by the numerical simulation. By fitting the results of the numerical simulation to the deflection of the sheet in this experiment, the transformation plasticity coefficient in the martensitic transformation of the chromium molybdenum steel was determined to be 21 x 10^-5 MPa^-1. In the third condition, chromium molybdenum steel sheet was quenched into semi-hot quenching oil to verify the accuracy of the prediction of heat treatment distortion using the determined transformation plasticity coefficient. The error in the deflection of the sheet after oil quenching using the determined transformation plasticity coefficient was reduced to 6% from 64% (the previous report). The accuracy of distortion prediction was improved by changing the specimen morphology used in oil quenching experiments from bars to sheets.