Research On Laser Additive Manufacturing Aeronautical Structures With K465 Superalloy

Laser additive manufacturing is a new manufacturing technology,which combines laser,computer,CAD/CAM,material and so on.The method of manufacturing K465 superalloy component with special cavity inside by laser additive manufacturing was studied,in order to meet the design requirement of aerospace component with special cavity inside,and ensure the mechanical properties at high temperature.The forming process is in the temperature field of a transient non steady state because of forming characteristics of the laser additive manufacturing,with the reciprocating movement of the molten pool,causing parts within a complex stress field,and prone to deformation and cracking process problems.Therefore,it is of great significance to study the process of Nickel-based superalloy by laser additive manufacturing.The forming process of Nickel-based superalloy parts was studied,in order to improve its forming quality.The forming process was controlled by printing and forming a kind of Aeronautical with thin wall and special cavity inside,and the microstructure and properties of the sample are analyzed.Therefore,the specific work done in this paper is as follows:First of all,the deformation and cracking were studied deeply,and the process control measures were put forward.Because the laser additive manufacturing process was to move the laser point source reciprocating forming parts,and then causing a complex stress field in the parts,the internal temperature gradient existed,so the process was easy to produce deformation and cracking problem.The mechanism of deformation and cracking which happening in cladding layer in the process of laser forming was deeply studied,the process parameters was further optimized,and a series of process control measures was put forward,such as the introduction of Stellite 6 cobalt base alloy,the forming substrate preheating,to eliminate internal stress etc.Secondly,the process parameters which has been optimized and the process control measures which has been proposed feasibly were applied to the forming process of aeronautical structural parts with large special cavity inside and thin-wall,and real-time monitoring and controlling its forming process,forming a set of processing technology of structures with large special cavity inside by laser additive manufacturing.Finally,in order to confirm that the microstructure and properties of the parts were significantly improved with the introduction of Stellite 6 alloy powder,the microstructure and properties of contrast samples under the same process parameters were analyzed.The macroscopic tissue morphology was observed by the stereo microscope and optical microscope,and the difference of macroscopic structure of the sample was analyzed;By using the electron microscope SEM and spectrometer EDS,the microstructure of the three groups of deposited samples were observed,the elements’ changes of the folded structure along the direction of deposition were analyzed.In the near crack area,the distribution of the components were analyzed,the distribution of the crack location was determined,and the possible mechanism of the crack was analyzed through EDS line scan;X-ray diffraction XRD was used to analyze the phase composition of the material,and the microhardness test was carried out by the microhardness tester,in order to obtain the variation of the hardness of the stack structure along the deposition direction.