TIG Wire and Arc Additive Manufacturing of 5A06 Aluminum Alloy

Wire and arc additive manufacturing(WAAM) was investigated by tungsten inert gas arc welding method(TIG), in which φ1.2mm filler wire of aluminum alloy 5A06(Al-6Mg-Mn-Si) was selected as deposition metal. The prototyping process was conducted by a TIG power source (working in AC mode) manipulated by a four-axis linkage CNC machine. Backplate preheating temperature and arc current on deposited morphologies of single layer and multi-layer were researched. The microstructure was observed and the sample tensile strength was tested. For single layer, a criterion that describes the correlation between backplate preheating temperature and arc peak current, of which both contribute to the smoothening of the deposited layer. The results show that the layer height drops sharply from the first layer of 3.4mm and keeps at 1.7mm after the 8th layer. Fine dendrite grain and equiaxed grain are found inside a layer and coarsest columnar dendrite structure at layer boundary zone; whereas the microstructure of top region of the deposited sample changes from fine dendrite grain to equiaxed grain that turns to be the finest structure. Mechanical property of the deposited sample is isotropic, in which the tensile strength is approximately 295MPa with the elongation around 36%.