Research On Laser Direct Metal Depositing And Repair Of Aerocraft Aluminum

Nowadays,the development and production of aviation aircraft are continuously moving toward lower manufacturing cost,higher service performance,and longer service life.Thus the parts and component,especially structural parts,are highly requested to be lightweight,complex,and structurally functional.However,as a novel technology,Laser Direct Metal Depositing(LDMD)has the characters of high forming efficiency and flexibility,low time consumption and the ability to produce parts with complex structure;and its unique rapid solidification process makes the parts dense and microstructure fine,which greatly improve the material properties of the metal parts.Meanwhile,due to the multiple advantages of aluminum alloy,such as simple manufacturing process,good mechinability and formability,high durability,high reliability and maintainability,good corrosion resistance,great specific strength and specific stiffness,and low cost.It has always been one of the main material for aircraft design and manufacturing,and has constantly maintained the dominant position of application on various aircraft around the world.In addition,there are large number of old-fashioned fighters serve in China,the proportion of Al alloy parts utilized on these aircrafts is large.It has a long service life,some aluminum alloy parts have been or will soon be ineffective,facing the shortage of replaceable spare parts.If these fighters need to be repaired and maintained,it is necessary to refurbish the damaged aluminum alloy parts.And the laser repair technology of the aluminum parts is undoubtedly the most feasible way to solve such problems.Therefore,laser direct metal depositing and repair technology for aluminum alloy parts of aviation aircraft has good research value and market prospect.In this paper,AlSi10Mg aluminum alloy(domestic brand ZL104)was taken as the research object,and the variation of the properties of the parts fabricated by laser direct metal depositing processing under different process parameters and cooling conditions was investigated.The main contents of this article include:(1).Construction of aluminum alloy laser direct metal depositing system,selection and introduction of experimental materials,and selection and determination of some experimental parameters.(2)Laser direct metal depositing process of AlSi10Mg aluminum alloy,and the influence of main process parameters such as laser scanning speed,laser scanning pattern and powder feeding rate on its cladding quality.A series of measurements and tests were carried out on samples with different process parameters for laser deposition.The macroscopic morphology,microstructure,defects and mechanical properties of the deposited layers were analyzed in depth.(3)The influence of the cooling conditions of the substrate during the laser depositing process on the deposition performance was investigated.By setting multiple groups of alloy laser deposition experiments with different cooling conditions,the experimental samples were tested and analyzed.The influence of substrate cooling conditions on macroscopic,microscopic structure,pore defect and mechanical properties of the deposited layer was obtained.