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

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 °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 °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.

► The martensite formation becomes saturated at ɛs = 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 °C for 30 s. ► The nanocrystalline 201L steel showed good combination of strength and elongation.