Interlayer valley temperature-regulated microstructural evolution and high-temperature wear resistance of WAAM hardfacing layers

Abstract

Wire arc additive manufacturing (WAAM) is promising for die repair and remanufacturing, but uncontrolled heat accumulation during multilayer deposition can cause microstructural instability and inadequate high-temperature wear resistance. In this study, an interlayer valley temperature regulation (IVTR) strategy was developed for a self-designed Cr–Mo–V hardfacing alloy to regulate heat accumulation and convert it into an in situ subcritical thermal treatment effect. Compared with the deposited metal without IVTR, the IVTRed hardfacing metal experienced more sufficient subcritical thermal exposure, promoting retained austenite decomposition and the precipitation of fine secondary carbides, increasing the average hardness from 47.71 ± 0.62 HRC to 55.99 ± 0.53 HRC. Consequently, the IVTR sample yielding a 42.5% reduction in the steady-state average friction coefficient and a 38.9% decrease in the specific wear rate. The enhanced thermal exposure via IVTR also improved the load-bearing capacity and tribo-oxide film stability, shifting the dominant wear mechanism from adhesive wear and fatigue delamination to oxidative wear accompanied with a more continuous O-rich tribo- film. This study leverages the residual thermal energy from WAAM for in situ heat treatment, thereby eliminating post-repair heat treatment and reducing associated costs in the die repair workflow.