Effect of annealing temperature on the microstructure and tensile properties of Fe-10Mn-10Al-0.7C low-density steel

The microstructure evolution and tensile properties of the Fe-10Mn-10Al-0.7C low-density steel annealed at the temperature range from 700 degrees C to 1200 degrees C for 1 h were investigated in the present study. The phases in the annealed specimens mainly included ferrite (alpha), austenite (gamma) and kappa-carbide (kappa). The dissolution temperature for kappa-carbide is between 850 degrees C and 900 degrees C. At the annealing temperature of 700 degrees C, all the. phase transformed to alpha phase and kappa-carbide by eutectoid reaction. As the annealing temperature rose from 700 degrees C to 900 degrees C, a phase and kappa-carbide fraction decreased and gamma phase fraction increased, and ultimate elongation increased, while ultimate strength and yield strength had a decreasing trend. The gamma phase fraction in the specimen dominated the ultimate elongation, and the kappa-carbide strengthened the specimen and weakened ductility. As the annealing temperature rose from 900 degrees C to 1200 degrees C, the phase fraction change was small but the grain size increased greatly. The rapid growth of the grains was the main reason why ultimate tensile strength and ultimate elongation decreased with the increase of annealing temperature over 900 degrees C. The steel designed here possessed a density of 6.80 g/cm(3), which is about 13% lower than pure iron. (C) 2015 Elsevier Ltd. All rights reserved.