Interface Evolution of Multilayer Hardfacing Structure on Quenched and Tempered Steel Using GTAW with Magnetic Arc Oscillation

Abstract To enhance the surface performance of quenched and tempered ultra-high toughness (UHT) steels for demanding industrial applications, multilayer hardfacing has emerged as an effective strengthening strategy. In this study, a Fe–Cr–C/ASS 316L/UHT multilayer hardfacing structure was fabricated using gas tungsten arc welding (GTAW) combined with magnetic arc oscillation (MAO). Emphasis is placed on the interface regions of the sandwich structure formed after sequential deposition, where the result reveals that MAO significantly alters the crystallographic architecture at interlayer boundaries by suppressing epitaxial columnar grain growth, promoting high-angle grain boundary formation, and enhancing orientation dispersion. Hardness testing in micro and nano scales revealed significant hardness gradients near the interfaces, which were effectively mitigated by the application of MAO. This effect is attributed to enhanced plastic compatibility between adjacent layers, enabled by MAO-induced microstructural refinement and uniformity, which facilitates strain gradient relaxation and mitigates interfacial stress localization. This work advances the understanding of interface phenomena in multilayer weld overlays and provides a framework for designing cladding strategies to enhance the hardness and application potential of UHT steels. Graphical Abstract