Investigating the Effect of Manganese Content on the Properties of High Manganese Austenitic Steels

In this study, in order to investigate the effect of increasing the manganese content on microstructure and mechanical properties of high manganese austenitic steels, three alloys with successive increases in weight percentages of manganese (7.55, 13.1, and 16.5) and carbon (0.8 and 1.2) were cast in the presence of a constant amount of chromium (1.5 wt.%) and silica (0.6 wt.%). The samples experienced solution annealing heat treatment comprised of austenitizing at 1100°C for 2 h followed by rapid quenching in stirred water. Hardness, tensile, and wear tests were conducted by dry sand/rubber-wheel abrasion method. Microstructural observations were performed by using optical (OM) and scanning electron microscopies (SEM) and energy dispersive spectroscopy (EDS). The obtained results revealed that after heat treatment a uniform austenite structure has developed in all three samples. With increase of weight percent of the elements from sample 1 to sample 3, the hardness value reaches from 191 to 218 Vickers. Also, with increase of manganese weight percent from 7.55 to 16.5, the ultimate tensile strength and wear resistance showed 11% and 29% increase, respectively, to the effect that the most enhanced mechanical properties and maximum wear resistance were observed in sample 3 with 16.5wt.% of manganese. This improvement in mechanical properties and wear resistance is related to the formation of the solid solution in the matrix, the increase of hardenability, and the increase of work hardening capacity resulted from the increase of manganese percentage. Examination of the abraded surfaces demonstrated that the involved wear mechanism was scratch wear mechanism.