Microstructural Evolution and Mechanical Properties of Type 304 L Stainless Steel Processed in Semi-Solid State

The paper discusses the effect of semi-solid processing on the microstructural evolution and mechanical property of 304L stainless steel. For the study, steel specimens were part ially melted and cooled to room temperatures in different cooling medium. The effect of temperature, t ime and cooling medium on microstructural evolution was studied by using optical microscopy. It was found that melting begins with the nucleation of liquid phase at the triple junctions and grain boundaries followed by propagation of the liquid phase along grain boundaries. The mechanical behavior of the semi-solid processed material was compared with that of the conventionally processed material with regard to their tensile properties and hardness. The semi-solid processed material shows better ductility and reduced YS and UTS than the conventionally processed counterpart. The correlation of the tensile properties and evolved liquid content shows that the UTS of the material decreases, while the YS increases with liquid fraction. The study also shows that there is a significant effect of cooling medium on the microstructural evolution and hence on the mechanical propert ies.