Effect of Aging Duration on the Microstructure and Corrosion Characteristics of 17-4 PH Stainless Steel

Heat treatment plays a critical role in inducing key microstructural changes necessary to enhance corrosion resistance of 17-4 PH stainless steel (SS). During the process, precipitates form within the metal matrix, contributing to the strength of the martensitic steel. Inconsistencies in the literature concerning the response of 17-4PH SS to heat treatment have been noted. Therefore, this study examines the impact of aging duration on microstructural characteristics, microhardness, and corrosion resistance of material. The solution heat-treatment process consisted of heating the material to 1040 °C for one hour and rapid cooling in water. Subsequently, aging treatment was carried out at 480 °C for varying durations of 1 hour, 4 hours, 8 hours, and 32 hours. Corrosion rates were measured through electrochemical tests using Tafel extrapolation method in a 3.5 wt.% NaCl solution. The findings indicated that aging durations had a significant effect on corrosion resistance, detailed microstructural analysis helped correlate corrosion behaviour with phase changes and precipitation formation. This study offers valuable insights for optimizing heat treatment processes to improve the durability and performance of 17-4PH SS in NaCl corrosion medium.