EFFECT OF AGING TIME ON THE ULTIMATE TENSILE STRENGTH OF MARAGING STEEL (03Ni18Co9Mo5TiAl)
Abstract
Maraging steel shows a very good combination of high tensile strength, high fracture toughness and dimensional stability during quenching and aging, so it is often used in high strength design applications. Research results proved that the above superior combination of maraging steel are completely dependent on its microstructure components. In this study, the microstructure of the steel was controlled through an appropriate heat treatment process including quenching and aging. Accordingly, the steel is quenched at a temperature of 830oC and then aged at 490oC for a period of 2 to 6 hours to evaluate the effect of aging time on the tensile strength of the steel. Analytical results on scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) indicate that there is a precipitation of intermetallic phase during aging, which greatly increases the durability. The tensile test results also showed that, during the aging period of 2 to 6 hours, the increasing aging time increased the strength. The durability value reaches its maximum at 2210 MPa corresponding to an aging time of 6 hours.