Mechanical behaviour and corrosion study of 304L austenitic steel processed by constrained groove pressing

Abstract

In the present work, 304L-austenitic stainless steel has been successfully processed till two passes of constrained groove pressing (CGP). The processed steel has been characterized using X-ray diffraction and a vibrating sample magnetometer. The XRD patterns and vibrating sample magnetometer confirms phase transformation (austenitic phase to martensitic phase). CGP of 304L austenitic steel improves mechanical properties such as tensile strength, yield strength and micro-hardness. The ultimate tensile strength value improves from 775 MPa to 1156 MPa, the value of yield strength improves from 332 MPa to 639 MPa and the microhardness improves from 244 VHN to 476 VHN for solution-treated, and two pass CGP processed specimens, respectively. The influence of CGP has also been reflected in electron backscatter diffraction (EBSD) results in terms of more substructure formation. The corrosion behavior has been estimated via linear polarization and electrochemical impedance spectroscopy tests. The CGPed 304L steel shows poor resistance to corrosion in comparison to parent steel. Polarization resistance values decrease from 27.88 to 12.63 kΩ/cm2 which represents loose and less protective passivating film after CGP.