Effect of the Annealing Temperature, Cooling rate and Cold Rolling Reduction Rate on the Bake Hardening a Low Carbon Steel

In this investigation, effect of annealing conditions as well as cold rolling reduction rate on the bake hardening property of low carbon steel was studied. This characterization is determined by measuring the yield stress increment between the values at 2% elongation and the higher yield strength due to strain aging after aging at 170C for 20 min. It was found to the annealing temperature has a significant effect in increasing the solute carbon content and enhancing bake hardening property. For the purposing of the role of cooling rate was applied two mode of cooling including slow and rapid cooling. It was observed that the cooling rate has not noticeably effect on the bake hardening value. However, in general, increasing cooling rate was caused increasing bake hardening property. This increasing could be due to prevention of carbide re-precipitation as well as making super saturation of carbon content in solid solution. Study of grain size showed that increasing this factor enhances bake hardenability.