Experiments of Laser Surface Engineering for the Green Remanufacturing of Railway Coupler

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To achieve sustainable development and to solve the question of resource recycling and environment protection, green remanufacturing should be considered in the life cycle of the used railway rolling-stock components. These invalidated components resulting from fatigue and wear, such as coupler, could be remanufactured using laser surface hardening technology as the key processing. The objective was to harden the coupler backend pinhole interface, and to repair the layer with wear and fatigue crack on the wall of pinhole. Laser transformation hardening and laser melt-solidification hardening was used to the new manufacturing process to improve wear resistance of the surface of coupler backend pinhole. Laser surface cladding was used to repair lost material area for the reason of wear or fatigue, in order to offset the geometry size and satisfy the assembly relationship, and to increase the strength, the hardness and the wear resistance of the substrate. To the E class steel, typical coupler metal, the related laser process variables and materials were test and optimized. For the sake of verification these tests, related hardening area mechanical behaviors examinations including hardness, wear resistance, impact resistance and metallographic examinations were given. The result of the examinations show that the laser hardening area joins with the substrate being metallurgic join, and the behaviors examined were equal or best than the substrate. These means that laser surface hardening technology could be applied to the green remanufacturing of railway couplers as key processing.