Correlative Analysis of Morphology–Mechanical–Corrosion Behavior of Conventional Nickel-Based and Nitrogen-Alloyed Nickel-Free Austenitic Stainless Steels

High-nitrogen austenitic stainless steel (HNASS) has been considered a potential material for various applications during the past decade due to its excellent properties. The present study aims to understand the structure–properties correlation of nickel-based and nitrogen-alloyed nickel-free austenitic stainless steels. Alloys (304L, 316L, 904L, 202, and HNASS) selected are solutionized at 1100 °C for 02 h. All the above metallography specimens are subjected to morphological analysis using optical and scanning electron microscopy (SEM). Using Vickers hardness, tensile, face-bend ductility, and Charpy impact testing, mechanical properties are evaluated. Localized corrosion studies, viz. open-circuit potential and potentiodynamic polarization, are performed using three-electrode-based GillAC electrochemical potentiostat in an aerated 3.5% NaCl environment. Further, the double loop-electrochemical potentiokinetic reactivation (DL-EPR) technique is used to determine the degree of sensitization (DOS) in a 0.5 M H2SO4+0.01 M NH4SCN environment. Intergranular corrosion attack is observed qualitatively using an etch test following ASTM standard A-262 practice A. The current investigation established that HNASS achieved a favorable microstructure and an optimum combination of mechanical and corrosion properties. It is attributed to solid solution strengthening, grain refinement, and re-passivation tendency involved due to the presence of nitrogen .