Fundamental investigation into the effects of in-process heat treatment in cold spray
Cold spray is a technology with great potential for additive manufacturing applications. Due to the high levels of plastic deformation experienced by the powder during the coating process, any deposit will require heat treatment post-spraying to improve ductility and fatigue strength. In extreme cases, the residual stresses from coating can cause delamination or compromise the bond strength when subsequent cold spray layers are deposited. This work details the use of a commercial laser system to perform a surface heat treatment on single lines of cold sprayed Aluminium, to relieve residual stresses. The effect of laser spot size, power, and traverse speed on material hardness and grain size when compared to as-sprayed and fully annealed deposits is quantified, and compared with predicted temperature distributions from FE modelling. The results shown in this work demonstrate the potential for in-process heat treatment to reduce post-processing time and improve coating quality by reducing residual stresses.