Effect of Bainite/Martensite/Retained Austenite Triplex Microstructure on the High Strain Rate Behavior of a One Step Quenching and Partitioning Steel

Abstract

The mechanical properties and microstructure evolution of a one step quenching and partitioning steel containing bainite/martensite/retained austenite mixed microstructure was studied though static and dynamic tensile tests (strain rates ranging from10-3 s-1 to 5×102 s-1 ).Scanning electron microscopy (SEM) and electron-back-scattered diffraction (EBSD) were applied to describe the microstructure evolution near the fracture. XRD characterization shows the volume fraction of retained austenite decrease exponentially with the strain rates increased.EBSD phase maps reveal that the first type of retained austenite is less sensitive to strain rate than the second type.