# Wire Arc Additive and High-Temperature Subtractive Manufacturing of Ti-6 Al-4V
## 3 Mechanical Properties of the Built Titanium Alloy  
Figure 9 shows the dimensions of the tensile test piece. Since the test piece might be deformed due to residual stress generated during the deposition process, the built object was subjected to stress-relief annealing under the conditions shown in Figure 10. The test piece was then cut out by wire electric discharge machining. The tensile direction was parallel to the torch traveling direction. We do not consider anisotropy between the \begin{table}
\begin{tabular}{l l l l l l l} \hline \hline  & \multicolumn{4}{c}{**wt\%**} \\ \hline  & **Ti** & **Al** & **V** & **O** & **N** & **H** \\ \hline Fabricated object & \multirow{2}{*}{Rem} & \multirow{2}{*}{5.45} & \multirow{2}{*}{4.18} & \multirow{2}{*}{0.232} & \multirow{2}{*}{0.0197} & \multirow{2}{*}{0.0083} \\ (After fabrication) & & & & & & \\ \hline Wire (Before & \multirow{2}{*}{Rem} & \multirow{2}{*}{6.00} & \multirow{2}{*}{4.14} & \multirow{2}{*}{0.15} & \multirow{2}{*}{0.007} & \multirow{2}{*}{0.0062} \\ \cline{3-3}  & & & & & & \\ \cline{3-3} AMS4911 & \multirow{2}{*}{Rem} & \multirow{2}{*}{6.75} & \multirow{2}{*}{4.5} & \multirow{2}{*}{0.20} & \multirow{2}{*}{0.05} & \multirow{2}{*}{0.0125} \\ \cline{3-3}  & Maximum & & & & & & \\ \hline \hline \end{tabular}
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Table 4: Change of elemental composition before and after WAM process measured with an oxygen/nitrogen analyzer and EDX. \begin{table}
\begin{tabular}{l l l} \hline \hline \multicolumn{2}{l}{Welding machine} & \multicolumn{2}{c}{Fronius TransTig 500 Job MV} \\ \hline Welding mode & \multicolumn{2}{c}{Plasma} \\ \hline  & & 1–3 layers & 140 \\ \multirow{2}{*}{Welding current} & \multirow{2}{*}{A} & 4–8 layers & 130 \\ \cline{3-3}  & & 9–10 layers & 120 \\ \multirow{3}{*}{Torch feed speed} & \multirow{3}{*}{mm/min} & 0–8 mm & 400 \\ \cline{3-3}  & & 8–95 mm & 180 \\ \cline{3-3}  & & 95–100 mm & 300 \\ \cline{3-3}  & & Back path & 400 \\ \hline Arc length & mm & 5 & & \\ \hline Wire/substrate material & \multicolumn{2}{c}{Ti-6 Al-4V} \\ \hline Wire diameter & \multicolumn{2}{c}{1.2} \\ \hline Shielding gas & \multicolumn{2}{c}{Ar} \\ \hline Shielding gas flow rate & \multicolumn{2}{c}{40} \\ \hline Plasma torch gas flow rate & \multicolumn{2}{c}{0.8} \\ \hline \hline \end{tabular}
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Table 3: Fabricating conditions of the additive process for cutting test specimen. \begin{table}
\begin{tabular}{l l l} \hline \hline \multicolumn{2}{l}{Work material} & \multicolumn{2}{c}{Ti-6 Al-4V} \\ \hline Tool diameter & mm & 32 \\ \hline Workpiece temperature & \({}^{\circ}\)C & Room temperature, 50, 100, 150, 200, 250, 300 \\ \hline Number of teeth & \multicolumn{2}{c}{1} \\ \hline Chip diameter & mm & 12.7 \\ \hline Cutting speed & m/min & 200 \\ \hline Feed rate & mm/tooth & 0.15 \\ \hline Axial depth of cut & mm & 0.5 \\ \hline Radius depth of cut & mm & 7.75 \\ \hline \hline \end{tabular}
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Table 2: Cutting test condition under varying workpiece temperature. deposition direction and the torch traveling direction here. The applied load during the tensile test was measured by the load cell at the upper crosshead of the tensile testing machine, and the strain and elongation were measured with both a strain gauge attached to the tensile test specimen and a digital extensometer. The crosshead moving speed was 5.0 mm/min. Figure 11 shows the true stress-strain diagram of each test piece. The tensile strength of each test piece was between 931 and 946 MPa; the 0.2% proof stress was between 891 and 892 MPa; and the elongation ranged from 6.6-8.9%. According to JIS H4657 of the Ti-6 Al-4V forging material standard, tensile strength, 0.2% proof stress, and elongation are 895 MPa or more, 825 MPa or more, and 10% or more, respectively. Based on this standard, the tensile strength and 0.2% proof stress met this required standard for forging material, but the elongation was slightly below the standard value. Elemental analyzers then evaluated the composition of the test specimen.