Microstructure and Mechanical Properties of Pressure-Quenched SS304 Stainless Steel

Bulk SS304 polycrystalline materials with ultrafine microstructures were prepared via a high-pressure self-heating melting and quenching method. Analyses of phase composition, grain size and microstructure were performed using metallographic analysis, X-ray diffraction, Rietveld refinement and transmission electron microscope (TEM). The effects of pressure and cooling rate on the solidification of SS304 were analyzed. Mechanical property test results show that, compared with the as-received sample, the hardness and the yield strength of the pressure-quenched (PQ) samples were greatly increased, the ultimate tensile strength changed minimally, and the elongation rate became small, primarily due to the large density of dislocations in the sample. The high-pressure self-heating melting and quenching method is an exotic route to process a small piece of steel with moderate properties and ultrafine microstructure.