Effect of Inter-Layer Cooling Time on Distortion and Mechanical Properties in Metal Additive Manufacturing

Laser Metal Deposition with wire (LMD-w) is one of the novel Direct Energy Deposition (DED) processes that is gaining the attention of various industries, especially aerospace, due to the potential cost and lead time reductions for complex parts. However, subjects of development include optimization of process parameters (for example laser power, wire feed speed, robotic travel speed, inter-layer cooling time etc.) for large scale adaption of this process. These parameters influence residual stress which potentially results in distortion and subsequent mechanical properties. Inter-layer cooling time is one of the main influences on production volume and is typically used to help control the cooling conditions to mitigate part distortion. Therefore, this paper is aimed at investigating different inter-layer cooling times on distortion and resulting mechanical properties of the parts produced by LMD-w. Distortion of deposited Ti-6Al-4V walls was measured automatically using a laser scanner, which was attached to the robotic arm itself. Finally, suitable recommendations are discussed to optimize the inter-layer cooling time to produce parts with desired mechanical properties.Mechanical Engineerin