Wire Arc Additive Manufacturing Of Aluminum Alloy Based On TIG Molten Pool Constraints

Wire Arc Additive Manufacturing(WAAM)is a manufacturing technology that uses arc as heat source and forms layers through continuous melting of wire.It has advantages of high deposition rate,simple equipment,and short production cycle.At this stage,considerable progress has been made in the field of aluminum alloy fabricated by WAAM,but due to its high deposition rate,the molten pool is prone to flow along the outer wall of the shaped part under the combined action of gravity,arc blowing force and surface tension,which resulting in a reduction in dimensional accuracy of the aluminum alloy.In this paper,TIG equipment and ER4043 aluminum alloy wire with?=1.2mm was used for WAAM.At the same time,a molten pool constraining fixture was used to make contact constraints on each layer pool,to ensure the mechanical properties while improving dimensional accuracy and shaped efficiency..Firstly,the influence of process parameters on the single-pass shaped was analyzed:The degree of influence on the penetration depth is from welding current,welding speed and wire feeding speed;the degree of influence on the cladding layer height is from feeding speed,welding current and welding speed;the degree of influence on the melt width is from welding speed,welding current,wire feed speed.Due to the heat absorption and restraining effect of the restraining plate under the constraints of the molten pool,some parameters cannot be continuously formed,the penetration depth is significantly reduced,and the cladding layer height is significantly increased.The process parameters of good forming and suitable for additive manufacturing was welding current I=125A,wire feed speed v_d=1100mm/min,and welding speed v_m=200mm/min.The dimensional accuracy of the formed part was optimal under the condition of the molten pool constraint distance of 6mm,the forming efficiency was increased by 35%,and the molten pool flow phenomenon was significantly improved.The molten pool constraints did not significantly affect the microstructure and phase composition.The grains in the near surface area showed a growth trend away from the constraining plate.The average microhardness of the center area of the molten pool constrained shaped part waas 56.5HV;The near surface area was66.6HV.The average microhardness of the center area of the unconstrained shaped parts was55.5HV,and the near surface area was 57.2HV.The average tensile strength and elongation of the pool constrained shaped parts X direction was 145.6MPa/22.7%,the Z direction was126.1MPa/13.0%,unconstrained shaped parts X direction was 143.9MPa/21.4%,and the Z direction was 126.8MPa/12.9%;.After solution aging treatment.The average microhardness of the center area of the unconstrained shaped parts was 48.6HV,and the near surface area was 49.1HV;the average microhardness of the center area of the molten pool constrained shaped parts was 47.5HV,and the near surface area was 48.3HV.After heat treatment,the tensile strength of the two samples was slightly reduced and the elongation was significantly increased.The average tensile strength and elongation of the pool constrained shaped parts X direction was 109.4MPa/35.5%,and the Z direction was 111.8MPa/21.0%;the average tensile strength and tensile strength of the unconstrained shaped parts X direction was 118.4MPa/32.8%,and the Z direction was114.7MPa/22.9%.