Production of nano/submicron grained AISI 304L stainless steel through the martensite reversion process

Production of nano/submicron grained AISI 304L austenitic stainless steel through formation of strain-induced martensite and its reversion to austenite are studied in this paper. The effects of annealing parameters on the microstructural development and mechanical properties are also investigated. Heavily cold rolling at 0 °C is employed to induce the formation of martensite in the metastable austenitic material, followed by reversion treatment at the temperature range of 700–900 °C for 0.5–300 min. Microstructural evolutions are analyzed using Feritscope, X-ray diffraction, and scanning electron microscopy, whereas the mechanical properties are determined by hardness and tensile tests. The smallest grain size (about 135 nm) is obtained in the specimen annealed at 700 °C for 20 min. The resultant nano/submicron grained steel not only exhibits a high strength level (about 1010 MPa) but also a desirable elongation of about 40%. Moreover, an annealing map is developed which indicates the appropriate range of annealing parameters for grain refinement of AISI 304L stainless steel through the martensite reversion process.