Research On Process And Property Of Selective Laser Melting With GH4169 Metal Powder

Contrary to traditional Subtractive Manufacturing or Forced forming manufacturing techniques,The principle of Additive manufacturing technology is to use the idea of calculus to add the material to the three-dimensional entities from bottom to top layered manufacturing,and ultimately complete the three-dimensional solid manufacturing process.Selective laser melting(SLM)technology is one method of metal material additive manufacturing technology.Because of its good high temperature strength,good resistance to oxidation and thermal corrosion,Domestic GH4169 high temperature alloy is widely used in aerospace and other fields.However,due to the use of traditional casting methods to produce GH4169 parts prone to macroscopic segregation and harmful Laves brittle phase and the forging method has a limitation on the geometry of the forming part,so the application of GH4169 superalloy is limited.However the use of selective laser melting process to produce GH4169 process can solve the above problems in traditional methods.In this paper,the parameters on the domestic GH4169 alloy powder selective laser melting process are studied.The parameters of the forming process(scanning pitch,scanning speed,laser power)were studied by one-way variable method.The density,surface quality and the hole of SLM molding parts are measured.Finally,the best processing parameters were obtained: the thickness of the powder layer was 40 um,the spot size of the laser spot was 100 um,the substrate was preheated 80 ?,the scanning distance was 70 um,the scanning speed was 1750 ~ 2250mm/s,and the laser power was 300 W ~ 375 W.The microstructure and properties of the molded parts were analyzed.The result shows that the microstructure of the selective laser melting parts is mainly composed of columnar crystals and cell crystals with dimensions less than 0.3um.The columnar grains are epitaxially grown through multiple beads and formes large-angle grain boundaries.The microhardness of the molded parts on different orientation is different,and the tensile performance of the molded parts is better than that of the castings standard.The heat treatment can greatly improve the hardness and tensile properties of SLM molded parts,as well as all of them meet the standard of forgings.Both the original and the heat treatment state are ductile fracture.