Aero-engine Blade Casting Temperature Field Of Numerical Simulation Of Defects In Laser Cladding Repair And Cladding Process

In this paper, blade with cast defect is repaired by laser cladding with Ni-based alloy powder made by ourselves. The best laser cladding parameter, microstructure, property ,Y₂O₃ and metamorphic materials on cracking susceptibility of coating are studied. In the same time, we make use of the FEM software ANSYS to simulate the temperature field of laser cladding process.The experimental results indicates that when P=1.5kW, V=180, 190mm/min, d=3mm, content of Y₂O₃ is 1.5wt. %, the perfect coating of laser cladding without any cracks can be obtained. Under the best laser cladding parameters, adding metamorphic materials can further fine microstructure of coating. When the content of Y₂O₃ is higher or lower than 1.5wt. % and adding metamorphic materials only , cracks or holes will appear inside the coating.When adding Y₂O₃ only and fixed other laser cladding parameter, the microhardness of coating increase with the increase of scanning velocity. When V=180, 190, 200, 210mm/min,the microhardness of coating are 414HV_0.1, 431.5 HV_0.1, 456.25 HV_0.1, 476.2 HV_0.1.The microhardness of coating is 375 HV_0.1 when adding metamorphic materials only. The microhardness of coating is 430HV_0.1 when adding metamorphic materials and Y₂O₃ in the same time.The microstructure of coating are investigated with OM,SEM,TEM,EPMA,EDS. The results show that in situ precipitate phase with the size of micrometer and sub-micrometer is mainly distributed along the grain boundary in the coating. The alloy phases of coating are comprised of γ-Ni, hexagonal W₂C, MoC and f.c.c TiC. Entwist dislocation is observed in the interface of precipitate phase and matrix phase in the coating.The numerical simulation results show that at the initial stage of laser cladding, the temperature increase fast in the heated area by laser beam. The highest temperature is 2939℃ when t=0.49s.Temperature field achieves the quasi-state in one second. Temperature field of quasi-state is mainly effected by boundary condition and the density of laser beam, different node has the same thermal circle curve ,only time is different. At the quasi-state the temperature is highest in the cladding process, depth of melting pool increase a little. The highest temperature is 3213℃ when t=1.03s, The highest temperature is 3354℃ when t=10.05s,the highest temperature is 3380℃ when t=17.1s.From 10.05s to 17.1s the temperature only raises 167℃.At the last stage of laser cladding stage, temperature rise quickly, the highest temperature is 3623℃ when t=17.85s,depth of melting pool obviously increase.