Research On Basic Technology Of Arc Additive Manufacturing Of Aluminum Alloy Commonly Used In Aerospace

The arc additive manufacturing has the characteristics of large forming size,high efficiency and low cost.It has significant advantages in the development of large-scale,integrated and intelligent aluminum alloy structural parts in several additive manufacturing methods.In this thesis,four common aluminum alloys,such as typical aluminum-magnesium-based aluminum alloy,aluminum-silicon-based aluminum alloy and aluminum-copper-based aluminum alloy,are used as research objects.The cold metal transition technology is used for the manufacturing process of aluminum alloy arc additive.The influence of process parameters on additive forming was discussed.The main findings are as follows:(1)In the single-layer single-path forming process of 5B06 aluminum alloy arc additive manufacturing test,the increase of forming current and forming speed in a certain range can help improve the wettability of the formed metal,but when forming current When it is to,m.o large,the phenomenon of lagging flow will occur when the material is added to a certain height due to the heat accumulation effect,and the thickness of the single layer is small when the forming speed is too fast,which affects the manufacturing efficiency of the additive.Based on the single-layer single-path additive test,the influence of key process parameters on the appearance of multi-layer single-path forming was further studied.It is found that in the C+P mode,as the forming current increases,the multi-layer single-path forming width gradually increases,but when the current is too large,the metal surface will undergo severe oxidation;as the forming speed increases,the metal oxidation phenomenon decreases.When the forming speed does not match the current,the formed metal is uneven.In order to achieve both forming efficiency and forming quality,it is recommended to use C+P or C+P+A two forming modes for arc additive manufacturing.The optimized multi-layer single-path arc additive manufacturing process parameters are forming mode(C+P).Forming current(90-120)A,forming speed(6-9)mm/s.(2)In the multi-layer single-path arc additive manufacturing test of aluminum-magnesium-based aluminum alloy 5356 and 5B06 aluminum alloy,in the C+P+A forming mode,the mechanical properties of the 5B06 aluminum alloy arc additive can reach(3)320MPa,the elongation is 23.5%,the mechanical properties between the path can reach 315MPa,and the elongation is 22.5%.The proper interlayer residence time can effectively avoid the crystal caused by the interlayer heat accumulation effect.The grain grows up;proper post-treatment can eliminate the internal residual stress,but when the post-treatment temperature increases,the grain growth tends to occur,resulting in a decrease in the forming mechanical properties.(4)In the multi-layer single-path arc additive manufacturing test of aluminum-silicon-based ZL114A aluminum alloy,the forming mode has little effect on the forming and forming of ZL114A aluminum alloy arc additive.The microstructure of ZL114A aluminum alloy arc additive is typical columnar dendrites,and fine Al-Si eutectic is distributed between the coarse a slats.There is no obvious precipitation strengthening phase inside the grain boundary.The tensile strength of the deposited state ZL114 is 160MPa-180MPa,the elongation is 2%-3%;the tensile strength after T6 heat treatment is increased to 330MPa-350MPa,the elongation is increased to 3.5%-5%,and the fracture mechanism is ductile and brittle hybrid fracture.(5)The single-wall additive forming of arc additive production of aluminium-copper system 2319 aluminum alloy is better,the microstructure is a typical equiaxed dendrite,a small number of columnar dendrites exist in the transition zone between layers.The mechanical properties of the sedimentary state are not good.After T6 heat treatment,the tensile strength is increased from 230MPa-250MPa to 390MPa-420MPa,and the elongation after fracture is obviously improved.However,the elongation between the layers and the inter-channel is much different,and the anisotropy cannot be eliminated by heat treatment.