Research On The 2319 Aluminum Alloy Arc Additive Manufacturing Process Based On The CMT

CMT arc and wire additive manufacturing was an arc and wire additive manufacturing process based on CMT technology.The combination of droplet transfer and wire withdrawal greatly reduced the heat input in the process of arc and wire additive manufacturing,and improved the process stability,forming characteristics and internal quality of components.In this paper,the exterior dimension,forming control,microstructure,mechanical properties and strength mechanism of 2319 high strength aluminium alloy were studied based on CMT arc and wire additive manufacturing process.Firstly,the forming regulation of single-layer and single-bead was studied.The quadratic regression model of weld bead size was established.It was found that the interaction between welding current and CMT processes on bead width,height and contact angle was significant,while the welding speed was not significant,and there was no interaction between welding current and welding speed.The influence of various CMT processes on the forming of multi-layer single-bead additive manufacturing was further studied.Results showed the CMT-PADV process with the smallest heat input had the highest deposition efficiency in the height direction,while the surface flatness and side flatness on the forming surface were the worst.At the same time,CMT-PADV process with smaller heat input was easier to form fine equiaxed grain structure,which made higher micro hardness,tensile strength and elongation.Next,the method of changing the welding current of each layer to respond to the temperature change was proposed to manufacture multi-layer and multi-bead block components.The microstructures of the block changed alternately between fine equiaxed grains and columnar grains of the remelting zone and cladding layer in the longitudinal direction,equiaxed grains and equiaxed dendrites in the transverse direction.Pores nucleated easily in the interlayer eutectic structure which makes the anisotropic mechanical properties between transverse and longitudinal directions.Finally,the effect of heat treatment process on the additive manufactured aluminium was studied.The direct aging treatment had little effect on strength enhancement.The micro hardness and strength of the alloy were greatly improved after solution treatment and aging treatment.The maximum tensile strength reached 510 MPa,and precipitation strengthening played the most important role.