Influence of laser strengthening techniques on anti-wear and anti-fatigue properties of rail welding joint

Abstract The fatigue damage of an on-site rail welding joint was analysed. The fatigue cracks were longer and deeper on the welding joint than on the normal rail material. The influence of two laser strengthening techniques, laser quenching (LQ) and laser shock peening (LSP), on the anti-wear and anti-fatigue properties of the welding joint were explored through rolling contact fatigue (RCF) tests. The LQ process significantly improved the anti-wear property of the rail welding joint, but the anti-fatigue property got worse. The wear rate of the LQ treated welding joint was decreased by 91.6–92.4%, however, the average crack angle (23–25°) and the average crack length (62–74 μm) on the LQ treated welding joint were larger than those on the untreated rail welding joint (13–15° and 37–59 μm, respectively). The LSP process improved both the anti-wear and anti-fatigue properties of the welding joint. The wear rate of the LSP treated welding joint was decreased by 5.1–10.1%. Meanwhile, the density of cracks (0.9–4.2 mm −1 ), the average crack angle (10–13°), and the average crack length (16–26 μm) on the LSP treated welding joint were smaller than those on the untreated and LQ treated welding joints.