2021 年 62 巻 8 号 p. 1071-1078
Wire + Arc Additive Manufacturing (WAAM) is an advanced manufacturing technology by inexpensive Gas Tungsten Arc Welding (GTAW) technology. Key microstructural features of the as-built WAAM alloy include large columnar β grains, grain boundary α colonies, and Heat Affected Zone (HAZ) banding, which generally leads to low ductility and anisotropy. In this study, Ti–6Al–xV (x = 0, 2, 4) alloys were prepared by WAAM, the effects of vanadium content on the microstructure, tensile properties and impact toughness were investigated. Irregular-shaped, plate-like features without columnar grains and HAZ banding were obtained in Ti–6Al alloy. Columnar grains were observed in Ti–6Al–2V alloy, and the grain size was further enlarged to more than ten millimeters by 4 mass% vanadium addition. With the increasing of vanadium content, a monotonic increase in yield strength and ultimate tensile strength can be observed, while the fracture strain and impact toughness changed in the opposite trend. Ti–6Al and Ti–6Al–2V alloy exhibited better matching of strength, ductility and impact toughness compared with Ti–6Al–4V alloy.
