Formation of Nano/ultrafine Grain Structure in a Ti-modified 201L Stainless Steel through Martensite Thermomechanical Treatment

Abstract

The formation of nano/ultrafine grain structure in a Ti-modified 201L austenitic stainless steel using the martensite thermomechanical treatment was investigated. Effects of Ti micro-alloy addition on the formation of strain-induced martensite (SIM) during cold rolling and austenite reversion during subsequent annealing were studied. The results showed that the nano-grained Ti-modified 201L steel with the average grain size of 45 nm possessed the yield strength of 1 000 MPa, ultimate tensile strength of 1 330 MPa and total elongation of 42%. Such improvement in mechanical properties of the thermomechanically processed steel is believed to be due to the formation of SIM supplemented with precipitation of Ti carbides.

Processing and Properties of Reversion-Treated Austenitic Stainless Steels

“…For 201 and 201L grades, the temperature of 850 • C has been found to be an adequate reversion annealing temperature resulting in complete reversion within 30 s and in the finest GS [15,16]. Kisko et al [27] obtained high tensile elongations (softened structure) in a 60% cold-rolled 201 ASS after 15 s at 800 • C. Sadeghpour et al [69] found that in a 201L + 0.12Ti steel, the reversion rate depends on temperature and holding time, so that the reversion seemed to be diffusion controlled. The temperature of 900 • C was convenient for the reversion within a soaking time of 60 s.…”