Microstructure and Properties of Ti-6Al-4V Alloy by Wire plus Arc Additive Manufacturing

Ti-6Al-4V alloy wire was molten by electric arc and then deposited layer by layer for the rapid prototyping of additive manufacture. Morphology, micro-hardness and mechanical properties of the Ti-6Al-4V alloy were analyzed. The results indicate that the deposit in the first and the second layers is in the form of columnar crystals and the rest are equiaxial crystals. Meanwhile, a fair amount of heat from arc ensures a good metallurgical bonding in all of the zones (deposition zone, fusion zone and deposition zone), and eliminates both clear deposition-layer and martensite of alloy. The integral alloy gets the stable alpha+beta lamellar structure and similar micro-hardness of all zones. Compared with as-cast Ti-6Al-4V alloy, the titanium alloy in this work obtains finer initial beta-Ti grains and shorter alpha+beta lamellar spacing by wire+arc additive manufacturing. The ultimate tensile strength and elongation of the Ti-6Al-4V alloy have increased by 3.6% and 37%, respectively. Besides, the tensile fracture morphology of the wire+arc additive manufactured alloy is ductile dimple clearly, which is different from tearing edged quasi-cleavage morphology of as-cast alloy.