Microstructure and Mechanical Properties of Hot-Rolled Low-Carbon Medium-Manganese TRIP Steels

Abstract

Transformation Induced Plasicity (TRIP) steels have attracted a growing interest in recent years due to their high strength and ductility combination.An alternative alloy and processing concept has been studied to evaluate the feasibility of producing low-carbon medium-manganese TRIP Steels. Conventional hot-rolling, and batch annealing processes were simulated with three laboratory heats of varying manganese content. The steels were found to be fully hardenable with conventional hot-strip mill processing and subsequent batch annealing simulations produced significant retained austenite levels. The combination of the prior martensitic microstructure in the as-hot-rolled condition, and austenite created during annealing,resulted in remarkable combinations of strength and ductility. Optimum properties were found when samples were annealed at approximately 630°C. While this treatment maded the tensile strength to 800-1020 MPa, the total elongation increased to between 27 percent and 35 percent. UTS*TE products exceeding 30,000 MPa*% were observed, making these materials attractive for high strength, high ductility applications.