Microstructural Evolution and Wear Behavior Involving the K-Carbides Precipitation of a Fe-25Mn-6.6Al-1.3C Austenitic Steel

In this paper, the microstructural evolution and mechanical properties of the as-cast Fe-25Mn-7Al-1.3C austenitic steel after different heat treatment were investigated. After solution treatment and subsequent aging treatment, the kappa-carbides with perovskite structure were found to precipitate coherently within the austenite matrix, which improved the initial hardness and mechanical strength. The experimental steel exhibited an optimal comprehensive performance after being solution treated at 1050 degrees C for 1 h and then aged at 550 degrees C for 2 h. The tensile strength was 751 MPa, the yield strength was 581 MPa, the elongation was 48%, the hardness was 252 HB, and the Charpy V-notch impact toughness was 168 J, respectively. The impact wear test was carried out on MLD-10 abrasive wear testing machine, and the worn out surfaces under different heat treatment were characterized by scanning electron microscopy (SEM). The results indicated that the abrasion resistance of the steel under the additional aging treatment was better than that of the as-solutionized steel. The optimal abrasion resistance was obtained after being soluted at 1050 degrees C for 1 h and then aged at 550 degrees C for 2 h. However, with the aging time increasing, the coarse kappa-carbides precipitating around the grain boundaries would deteriorate toughness, which lead to increase of the abrasive wear volume loss. Besides, obvious micro-cracking and relatively larger peeling pit were observed.