Influence of temperature in arc-activated plasma nitriding of maraging steel in solution annealed and aged conditions

Abstract Maraging alloys are a group of high performance steels that combine high strength and good fracture toughness. Their excellent combination of properties is due to their microstructure, formed by nanometer-sized intermetallic precipitates embedded in a ductile martensite matrix. Their hardening treatments consist of aging processes that are compatible with thermochemical treatments such as nitriding or nitrocarburizing. An arc-activated plasma nitriding technique has been used in this study to investigate the effect of simultaneous aging and ion nitriding of maraging steel grade 300 at temperatures from 450 °C to 510 °C. The paper compares the results obtained for solution annealed and aged hardened samples in order to verify the compatibility of both processes, aging and nitriding. Chemical composition and micro-hardness profiling, glancing incidence X-ray diffraction (GIXRD), metallographic tests, corrosion studies and wear resistance tests were carried out. The results demonstrate the feasibility of arc-activated ion nitriding to achieve significant improvements of the surface properties of maraging steels and to merge together thermochemical and aging processes, thus reducing their processing time and energy consumption.