Abstract: The influence of surfacing material and processing parameters on the quality of light beam powder surfacing layer is investigated. When single-pass and single-layer surfacing is used, too big thickness of pre-coating can result in a poor bond between surfacing layer and base metal. On the contrary, the macrohardness of surfacing layer decreases obviously owing to high dilution when the pre – coating is too thin. The transverse crack in surfacing layer, porosity in bead edge and non-fusion between layers are the defects that are liable to produce when multi-layer surfacing is used. When multi-pass lap surfacing is used, non-fusion can easily arise between neighboring beads. Adding wettable metal ceramics (WC with Ni coating) to Ni-based alloy and controlling the content of ceramics are the key factors to acquire the high quality composite surfacing layer. When heat input is controlled reasonably, toe of weld is cleaned thoroughly and molten pool is protected rationally, the non-defect surfacing layer with big thickness and area can be acquired.

Key words: Light beam powder surfacing, Ni-based alloy, Quality control