Dynamic bake hardening of interstitial-free steels

Two types of dynamic strain aging (DSA) strengthening methods were investigated to determine their potentials fur industrial use. They are referred to here as dynamic-static bake hardening (DSBH) and dynamic bake hardening (DBH). For this purpose, a 0.06 pet Ti interstitial-free (IF) steel was reheated to 900 degrees C and cooled at 12 degrees C/s to room temperature. It was then dynamically bake hardened in the temperature range 100 degrees C to 250 degrees C to strains of 2 to 8 pct at a strain rate of 10(-3) s(-1). The tensile properties were determined before and after these treatments. It was found that the occurrence of DSA during dynamic baking led to significant increases in work-hardening rate as well as in the final strength. The results indicate that, for a given solute carbon level, the dynamically and then statically aged samples have higher strengths than those that are bake hardened in the conventional way.