Enhancement in tribological performance of copper through interpass arc remelting during WAAM-TIG fabrication

Abstract

Copper (Cu) is a widely used material owing to its exceptional thermal and electrical conductivity. However, the adoption of Cu-based components remains constrained in high-temperature applications, including rocket engine cooling channels and electrical contacts, owing to inferior tribo-mechanical performance. The present study explores interpass/interlayer arc remelting during wire arc additive manufacturing utilising TIG as a heat source (WAAM-TIG) to enhance the high-temperature tribological performance of pure copper. It was observed that the as fabricated (AF) samples showed a significant increase in specific wear rate, ~6 times and ~10 times, when the temperature raised from room temperature (25 °C) to 250 °C, and further to 550 °C, respectively. However, an exceptional trend was observed when the interlayer arc treatment was introduced either in continuous (ATC) or pulsed (ATP) mode. At 25 °C, it was decreased ~3 times, whereas at 250 °C and 550 °C, it decreased to ~2.5 and ~4.5 times, respectively. This interpass arc remelting played a crucial role in microstructural refinement from ~310 µm (AF) to ~86 µm (ATC) and ~79 µm (ATP), leading to enhanced tribological performance in both room (25 °C) and elevated/high (250 °C and 550 °C) temperatures. It also enhanced the scratch hardness and fracture toughness from 0.49 GPa/7.25 MPa·m¹ᐟ² of AF to 0.77 GPa/13.38 MPa·m¹ᐟ², and 1.06 GPa/26.03 MPa·m¹ᐟ² for ATC and ATP samples, respectively, by improving densification and reducing porosity. Comprehensively, this study demonstrates an effective interlayer arc treatment strategy that markedly improves the high-temperature tribological performance of Cu components for industrial applications. © 2026 Elsevier Ltd.