ON THE DECOMPOSITION OF AUSTENITE IN A HIGH-SILICON STEEL DURING QUENCHING AND PARTITIONING

摘要

Using a Gleeble thermomechanical simulator, a high-silicon steel (Fe-0.2C-1.5Si-2.0Mn-0.6Cr) was austenitized, quenched into the M_s-M_f range retaining 15-40% austenite, and annealed for 10-1000 s at or above the quench-stop temperature (T_Q) in order to better understand the mechanisms operating during partitioning. Dilatometer measurements and electron microscopy showed that besides carbon partitioning, isothermal martensite and bainite form at or close to the partitioning temperature. At high partitioning temperatures, martensite tempering competes with the partitioning process. Bainite as well as martensite can form on cooling from the partitioning temperature. The final fraction of retained austenite is a complex function of the heat treatment parameters.