A novel multi-stage pressuring strategy to fabricate sound high‑carbon steel joints in rotary friction welding

Abstract

Rotary friction welding (RFW) was employed to join high‑carbon steel SKH51 rods. To mitigate the risk of brittle martensitic transformation at the weld interface, high friction pressure and low rotation speed were used to achieve a welding temperature below the A₁ point. However, the welding temperature exhibited an inherent inhomogeneity across the weld interface, leading to unbonded areas formed at the interface center due to the insufficient heat input. A novel multi-stage pressuring strategy was therefore proposed, wherein the friction pressure was intentionally adjusted at different stages to regulate the pressuring and heat generation behaviors at both the interface center and periphery. A homogeneous temperature distribution below the A₁ point and complete interfacial bonding were successfully achieved across the entire weld interface, enabling the multi-stage RFW SKH51 joint to exhibit exceptional tensile properties comparable to those of the base material.