Influence of powder flow on sidewall quality of solid parts in laser metal direct forming

In order to improve the sidewall quality of solid parts in laser metal direct forming, the paper focused on the difference of powder quantity actually injected into molten pool at the edge and inner positions when forming the solid parts, and the influence of curvature radius of the solid part’s edge on the powder quantity injected into the molten pool at the edge position was also investigated. The result shows that the distance between the cladding point and the solid part’s edge seriously affects the powder quantity injected into the molten pool and that the powder quantity injected into the molten pool at the edge positions is about 1.2 times more than that at the inner positions. However, the change of curvature radius of the solid part’s edge has little effect on the quantity of powder injected into the molten pool. The sidewall roughness of solid parts can be effectively reduced by increasing the powder feeding rate at the edge positions to about 1.2 times more than that at the inner position. Using this powder compensation method, a tip of turbine blade with the sidewall roughness Ra of 16.2–20.8 μm was fabricated.