Studies on Microstructure Evolution, Mechanical, and Corrosion Behaviors of Cryorolled 316L Steel

In this present work, the effect of cryorolling on microstructural evolutions, mechanical properties, magnetic properties, fracture mode, and corrosion behavior of 316L austenitic stainless steel was investigated. For this solution-treated 316L steel of thickness, 3 mm has been deformed to various amounts of plastic deformation (30, 50, 70, and 90% reduction in thickness). Microstructural characterization and phase change were done using optical microscopy, x-ray diffraction, field emission scanning electron microscopy equipped with electron backscatter diffraction detector, vibrating sample magnetometer techniques. Mechanical properties of the processed steel were examined using tensile and Vickers microhardness tests. The fracture mode of the fractured surfaces after the tensile test was also determined by SEM. In order to study the corrosion behavior, linear polarization and electrochemical impedance spectroscopy tests were performed. Results of the study showed that cryorolling leads to the transformation of parent austenitic phase to deformation-induced martensite (alpha '-martensite) phase, with the increase in percent deformation, which is also confirmed through magnetic characterization. Cryorolling too leads to improved yield strength, tensile strength, and microhardness values as well as a decrease in ductility of the steel. The yield strength, tensile strength, and hardness values increased from 398 to 1496 MPa, 781 to 1805 MPa, and 200 to 500 VHN, respectively. The fractography of fractured tensile samples shows the change in the fracture mode from a typical ductile fracture to a brittle fracture. Also, cryorolling over 316L affects its resistance to corrosion.