Study On Wire And Arc Additive Manufacturing Process And Post-processing Of 6061 Aluminum Alloy

Wire and Arc additive manufacturing technology is an advanced manufacturing technology that uses arc as a heat source to manufacture metal solid components by layer-by-layer cladding and stacking.Due to the uniform chemical composition,high density of arc additively formed components,and less restrictions on the size of formed components,and has the advantages of high stacking efficiency,short overall manufacturing cycle and low cost,so it has received extensive attention.With the improvement of material performance requirements,people have begun to explore post-processing methods for arc additive components in order to obtain better comprehensive performance.This paper takes 6061 aluminum alloy as the research object,explores the appropriate process parameter window for arc additive manufacturing,and conducts different heat treatments and friction stir treatments on wellformed arc additive components to study its effect on the hardness,The influence of tensile properties was analyzed,and the microstructure of different regions of the sample treated by friction stir treatment and heat treatment combined process was analyzed from the aspects of forming morphology,metallographic structure,fracture scanning,etc.The main conclusions are as follows:(1)When the welding parameters of 6061 aluminum alloy arc additive manufacturing are in the ratio F/T of wire feeding speed and welding speed between 0.5 and 1,and the wire feeding speed T is selected between 5 and7 m/min,a good weld bead can be obtained.appearance.Under the condition that the other conditions remain unchanged,as the wire feeding speed increases,the residual height and width of the molten pool will gradually increase,but if the molten width is too high,the collapse of the molten pool will occur;as the welding speed increases,The melting width and residual height of the additive samples were reduced.Different stacking paths have different effects on the forming morphology of arc additive components.Reciprocating stacking and speed control can effectively adjust the forming morphology of 6061 aluminum alloy arc additive components.After adjustment,the surface of the component is smooth and the collapse at both ends is small.After the stacking of each layer is completed,the temperature of the component is reduced to a certain level by adjusting the residence time between layers,and it is extended with the increase of the stacking height in order to obtain a good forming shape.(2)For arc additively manufactured formed components,the junction between the weld bead layer and the layer is the bonding layer,and the rest of the area is the deposition layer.The bonding layer and the deposition layer show a morphology of alternating gray and white bands along the stack height direction,and All show a state of multiple pores of various sizes,and the grain size of the bonding layer is larger than that of the deposition layer;the hardness of the formed components does not change much along the stacking direction,and the hardness of the bonding layer is lower than that of the deposition layer,and the hardness fluctuation is larger.The overall average The hardness is 75.82 HV.There is little difference in the strength in the horizontal direction in different regions.There is anisotropy in the mechanical properties of the arc additively formed components.(3)The cooling rate after heat treatment will affect the transformation of the iron-rich phase,resulting in uneven distribution of alloying elements.The hardness of the water-cooled arc additive sample after heat treatment will fluctuate more,indicating that the degree of homogenization of its elements is relatively low.The mechanical properties of the arc additive samples cooled with the furnace are more stable,and the hardness fluctuation is smaller,and the air-cooled treatment is in the middle.Different heat treatment processes have an important impact on the microstructure and properties of arc additive components.The suitable T6 heat treatment process for 6061 aluminum alloy arc additive components is: 380℃ annealing heat treatment x2h(furnace cooling),530℃ solution quenching heat treatment x1h(water cooling),160 ℃ complete aging treatment x12h(furnace cooling),compared with the arc additive components without heat treatment,the overall average hardness increased by 25.7%,the tensile strength increased by 7.1%,and the elongation increased by 6.1%.(4)The uneven surface will affect the friction stir treatment of the arc additive components.The arc additive components after milling have a larger process window for the friction stir deformation treatment.Within the range of 100r～400mm/min,no obvious defects can be produced after the friction stir deformation treatment.The flash formed around the weld bead on the macroscopic morphology is small,the structure is uniform and dense,and the material fluidity is good.The welding surface is relatively flat.After the arc additive component is combined with friction stir deformation treatment and T6 heat treatment,compared with the component without any treatment,the overall average hardness of the stirred + T6 heat treatment component increased by 36.12%,the average tensile strength increased by 10.84%,and the average yield strength increased.22.3%,The difference between the horizontal and vertical elongation is smaller,which shows that the anisotropy of the 6061 aluminum alloy arc additive component after stirring and heat treatment is weakened.