Investigation on repairing 30CrMnSiNi2A steel with laser additive and subtractive hybrid remanufacturing technology

The 30CrMnSiNi2A ultra-strength steel features excellent comprehensive mechanical properties and has been widely used to manufacture structural parts such as the aircraft landing gear, the wing girder, the missile engine shell, etc. However, wear and defects are produced on the surface of these parts in the course of their long-term service. In this paper, a continuous-wave laser deposition and pulsed laser finishing hybrid technique was proposed to repair 30CrMnSiNi2A ultra-high strength steel. The microstructure and mechanical properties of 30CrMnSi2A alloy matrix, laser repairing and laser finishing parts were compared. Laser finishing parameters were optimized to further improve the surface properties of the repaired parts. The effect of different process parameters on the surface morphology, microstructures, micro-hardness and wear resistance was explored. The results revealed that the comprehensive surface properties of repair parts with an average surface roughness of 1.12 µm, a micro-hardness of 595.22HV and a wear rate of 4.78 × 10−3 mm3/N·m can be obtained with laser finishing. And, the surface roughness and wear rate were reduced by 64.96% and 27.68% respectively, and the micro-hardness can be improved 23.67% compared with the parts without laser finishing.