Insider-laser coaxial powder feeding laser cladding is one kind of technique, which can be used in metal part directly manufacturing field. Compared with outsider-laser coaxial powder feeding laser cladding techniques, it has significant advantages [1]. In order to research the effect of defocus distance on the layer quality in insider-laser coaxial powder feeding laser cladding, it has taken some expriments in this paper to study the layer quality by constantly changing the defocus distance, with other laser cladding process parameters invariable. In addition, this paper measues, analysis the cladding layer’s width, height, the surface quality (including surface flatness, flat-wide ratio and flat-high ratio [2]), hardness and microstructure, then summarizes the effect of the defocus distance on the layer quality in this paper.

Based on the forming technology of "hollow laser beam and internal powder, adopting a novel device with coaxial inside-beam and internal powder feeding, the accumulation experiments of the change-diametral rotary parts are carried out on the substrate of 45# steel. This study is focused on the control of the parts inclination angle, Z axis incremental and laser power on the forming characteristics of the parts. The results show that with the Coaxial Inside-beam Powder Feeding Accumulation, the quality of molding parts that this experiment gets finally is higher with smooth appearance and lower roughness. The grain is fine and the microstructure distribute uniformly from bottom to top of forming parts.

The effects of process parameters such as laser power, scanning velocity and wire feeding speed on weld joint quality has been discussed through some laser welding experiments using coaxial inside-beam wire feeding process method. The results reveal that: Along with the increase of the laser power, weld width and depth are increasing gradually; Coating surface will appear burning loss and deboss when laser power is too large. The increase of scanning velocity decreases the depth and width of molten bath, and abates laser hole-effect, so the metal plate can not be welded penetration. Larger wire feeding speed can avoid welding seam produce burning loss, but it also can strengthen welding wire reflect the laser, and decline the welding.