Effect of stacking-fault energy on dynamic recrystallization, textural evolution, and strengthening mechanism of Fe−Mn based twinning-induced plasticity (TWIP) steels during friction-stir welding

Abstract

This study aims to elucidate the effect of stacking fault energy (SFE) on the microstructural evolution and related hardening mechanisms of Fe−18Mn−0.6C−(0 and 1.5)Al and Fe−30Mn−3Al−3Si (wt.%) twinning−induced plasticity (TWIP) steels during friction stir welding (FSW) using a high−resolution electron backscattered diffractometer. With increasing SFE, the intensities of the Goss, CuT, and Brass components increased via active dynamic recrystallization (DRX) accompanied by twinning. The 30Mn weld, which had the highest SFE, exhibited the highest recrystallization fraction (94.8 %) and an increasing rate of hardness (40.9 %). This is because a higher SFE can enhance dislocation mobility, leading to an active rate of continuous DRX as well as discontinuous DRX. Consequently, the refinement of the recrystallized grains effectively assisted the hardening of the 30Mn weld after FSW. Hence, we concluded that SFE should be considered to improve the properties of TWIP steels after FSW.

Keywords

• Twinning-induced plasticity (TWIP) steel
• Stacking-fault energy (SFE)
• Friction-stir welding (FSW)
• Dynamic recrystallization
• Texture