Study Of Technology And Mechanical Property On The Direct Fabricated Metal Parts By Laser Cladding

Direct laser fabrication (DLF) based on laser cladding is an advanced manufacturing technology, which was developed from rapid prototyping (RP). At present, lots of fundamental researches have been carried on in the past years and big progresses have been made in this field at a rapid speed. This paper aims at studying the direct laser fabrication of stainless steel parts by laser cladding to optimize the laser processing parameters. Firstly, the processing planning of fabricating stainless steel parts by DLF is presented. Especially, the components of the system are introduced systematically and the main operation principle is described. This whole system is divided into three subsystems by function, including laser system, CNC processing system and powder delivery system. The research of laser processing technologies is the basis of direct laser fabrication. To obtain the stainless steel parts with high precision and the excellent quality, the influence of many processing parameters on sizes of cladded coatings, precision and surface quality has been analyzed in detail. These parameters include: laser power, scanning speed, ratio of overlapped and Z-increment for each layer. Additionally, the paper also discussed the influence of equipments on the quality of the metallic parts by DLF. The results show that for getting the parts with best quality by DLF, the value of overlapping ratios should be greater than that of the spot sizes. And furthermore, the optimum matching of laser power, scanning speed, powder delivery speed and Z-increment is necessary. Finally, through tensile test and analysis of the fracture surface, the mechanical properties of the metallic parts made by DLF with different path-filling models as well as the fracture mechanism of tensile samples were studied systematically. The results show that the fracture character of tensile samples with high bond strength is ductile rupture, and the yield strength and the rupture strength are higher than the corresponding values of samples with the conventional processing methods. The genesis of defects in parts is also discussed in this paper, and the defects can be eliminated by improving the laser power properly and preventing the oxidation. These results are significant to promote DLF technology and accelerate practical application in industry.