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Ti-Al(48at.%) alloy was deposited by twin-wire plasma arc welding additive. The preheating temperature was 560, 620 and 680 °C, respectively. The results show that when the preheating temperature was 560 and 620 °C respectively, cracks appeared at the arc-starting part of the lower of the sample. The preheating temperature was 680 °C, and the sample had no cracks. The numerical simulation results show that the transient stress decreased with the increased of the preheating temperature. The transient stress at the lower of the specimen was greater than that at the middle and top, and the YZ shear stress and Z-direction stress at the front end were greater than those at the middle and end, resulted in cracks at the arcing starting part of the lower. [ABSTRACT FROM AUTHOR]

Herein, the deposition of a Ti–Al(48 at%) alloy via twin‐wire arc additive manufacturing (WAAM) using plasma arc welding (PAW) and tungsten inert gas (TIG) welding arc sources is presented. The microstructure and the phase composition of different regions of the alloy are analyzed using metalloscopy and X‐ray diffraction. The transient temperature field and residual stress distribution are measured before and after the process, respectively. A transient thermostress model is established using the finite‐element method. Results show that the alloy is composed primarily of α2‐Ti3Al and γ‐TiAl phases, while the microstructure evolution during the Ti–Al(48 at%) alloy deposition process is described. The thermal conductivity in the lower region of the alloy far exceeds that in the middle and upper regions. The thermal conductivity is smaller in the upper region and the midregion, resulting in the increase in heat accumulation. Due to arc shrinkage and reduced heat input, the PAW process reduces the heat accumulation and stress distribution differences more effectively than the TIG process. [ABSTRACT FROM AUTHOR]