Production of nano/ultrafine grained AISI 201L stainless steel through advanced thermo-mechanical treatment

Highlights: → The martensite formation becomes saturated at εs = 0.5. → The rate of martensite reversion was very high for the primary annealing times. → The smallest average grain size of 65 nm is achieved by annealing at 850 deg. C for 30 s. → The nanocrystalline 201L steel showed good combination of strength and elongation. - Abstract: In recent years, great attention has been focused on the development of nanostructured stainless steels to improve their mechanical properties. This work reports the formation of nano/ultrafine grain structure in the AISI 201L stainless steel using advanced thermo-mechanical treatment. The cast specimens were first homogenized and then hot forged to provide a suitable microstructure prior to the treatment. Cold rolling was carried out with the reductions of 10-95% followed by annealing at temperature of 850 deg. C for 15-1800 s. X-ray diffraction, optical and scanning electron microscopy, and tensile and hardness tests were used to characterize the processed specimens. The results showed that the nanocrystalline austenitic structure with a grain size of about 65 nm was obtained by annealing at 850 deg. C for 30 s after the cold reduction of 95%. The yield strength, total elongation and hardness of this specimen were measured as 1485 MPa, 33% and 386 Vickers, respectively.