Optimization of asymmetric process parameters for molten pool flow and powder divergence in multiangle laser cladding

When conducting on-line repair or remanufacturing of nondetachable and nonrotatable equipment using laser cladding, the laser cladding head is inclined to the position to be repaired. Gravity causes low powder utilization and asymmetrical molten pool morphology, leading to repair difficulties and poor quality. This study has proposed an asymmetric optimization strategy for multiangle laser cladding. By increasing the carrier gas flow rate or decreasing the powder-feeding voltage in two powder-feeding tubes at the bottom of the nozzle, a stable and nonsagging cladding layer can be achieved. Initially, a multiphysical field coupled model integrating powder, gas, laser, and molten pool was constructed. Subsequently, the effects of asymmetric process parameters on the offset of the cladding layer were explored through simulation, and the optimization rate of the offset can be as high as 13.04%. The experimental results of multiangle single-layer multi-channel laser cladding show that flatness has been significantly improved, for example, from 75% to 92% at 60° and from 62% to 82% at 120°. In addition, the average microhardness was substantially enhanced, and the maximum optimization rate was 19.08%. Tensile tests conducted before and after asymmetric process optimization demonstrate substantial increases in tensile strength, yield strength, and elongation. Fracture morphology analysis further indicated that the optimized cladding layer undergoes more adequate and uniform plastic deformation during tension, thereby greatly enhancing its mechanical properties. These findings provide valuable insights for enhancing the performance of multiangle laser cladding processes.