The impact of the surface convection generated by argon shielding gas used during Laser Engineered Net Shaping (LENS) on the deposited part is investigated. LENS generates complex thermal histories in the build that are dependent upon the material, part geometry, laser heat input, mass feed rate, and radiative as well as convective cooling. It has been shown that the deposition track and final part quality are subject to many of these considerations; however, no investigation has been undertaken to understand the impact of surface convection resulting from changing the argon shielding gas flow rate. A thermo-mechanical finite element analysis with measurement-based convection models is used to study the effects from different argon shielding flow rates on the temperature history, distortion, and residual stress of thin wall Ti-6Al-4V structures. The results from three cases show that reducing the shielding flow rate by half increases the temperature by 5% to 13%, while decreasing the deflection and residual stress.

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