Designing Q&P Process for Experimental Steel with 0.47 % Carbon Content
The Q&P process (Quenching and Partitioning) is a heat treating method for high-strength low-alloyed steels. It delivers the desired combinations of high strength and adequate ductility. These properties are achieved thanks to the unique martensitic microstructure with a certain volume fraction of stable retained austenite. Retained austenite imparts plasticity to the otherwise brittle martensitic structure. Optimum mechanical properties are achieved by using correct processing parameters and chemistry of the material. The experimental material was a steel with 0.47 % carbon alloyed with silicon, manganese and chromium. The purpose of the effort was to optimise the heat treating parameters in order to obtain a strength level above 2000 MPa and an elongation of no less than 10%. In the first step, the appropriate austenitizing temperature was identified. In the second, effects of various quenching temperatures and cooling rates on the microstructure evolution were explored. In the third, the impact of raising the partitioning temperature on stabilization of retained austenite was examined. Adjustment of the parameters led to a strength of more than 2300 MPa and an elongation of 8 %.