Tensile Properties and Microstructure of Fe–17Mn–2Al–0.6C TWIP Steel
Davood Zamani, Azmah Hanim Mohamed Ariff, Ghasem Dini, Zainuddin Sajuri, and Nur Ismarrubie Zahari
The tensile properties and microstructure evolution of Fe–17Mn–2Al–0.6C TWIP steel exposed to 80% cold rolling reduction, and annealed at diﬀerent temperatures were experimentally investigated in order to promote strength–ductility synergy. For this purpose, uniaxial tensile tests were performed on specimens obtained from 80 % cold-rolled sheets, and subsequent annealed at 550, 575, 610, 650, 750, 850, and 1100 ºC, for 30 min. Then, the resulted microstructures were examined by a scanning electron microscopy and a transmission electron microscopy. The results indicated the yield strength and ultimate tensile strength mainly decreased as annealing temperature increased, while the total elongation greatly increased. The variation in the product of ultimate tensile strength and total elongation against yield strength was linked to the annealing temperature. The most evident change in strength and elongation was located between 575 and 610 °C, due to the fraction of recrystallized areas. The fraction of recrystallized areas and grain size increased with increasing annealing temperature. TWIP steel microstructure designs that rely on annealing treatments in the recovery and also lower limits for the partial recrystallization regions, provide opportunities to develop TWIP steel that offer superior combinations of elevated yield strength (i.e., above 1350 MPa), along with considerable product of ultimate tensile strength and total elongation (i.e., above 25 GPa%). To get maximum value for the product of ultimate tensile strength and total elongation, the grain sizes of 7.4 and 16.8 µm for the TWIP steel were suggested, within which it reached more than 75 GPa%.