Effect of Inter-layer Cooling Time on Distortion and Mechanical Properties in Metal Additive Manufacturing (AM)

Abstract

Laser Metal Deposition with wire (LMD-w) is one of the novel Direct Energy Deposition (DED) processes that is gaining attention in aerospace industry due to the potential cost and lead time reductions for large-scale components. However, improving process parameters (for example, laser power, wire feed rate, robotic travel speed, inter-layer cooling time, etc.) is still under development. These parameters affect thermal gradients that cause residual stresses that in-turn influence distortion. These parameters also affect mechanical properties. Inter-layer cooling time, specifically, is one of the main factors for total production time, and it is used to help mitigate distortion. Therefore, this paper investigated the effects of different inter-layer cooling times on both distortion and mechanical properties. Distortion of deposited Ti-6Al-4V walls was measured automatically using a laser scanner. Finally, suitable recommendations are discussed to optimize the inter-layer cooling time to fabricate components with desired mechanical properties.