Abstract
Cold Spraying (CS) is a thermal spray process capable of producing dense and thick coatings by the spraying of powders under high velocity and relatively low temperature. The high deposition efficiency and the thickness of each pass make possible the use of CS to produce freestanding parts, as an additive manufacturing process (CSAM). Traditionally, CS is performed spraying perpendicularly to the substrate, which ensures maximum deposition efficiency among other benefits. This, however, presents two main disadvantages for CSAM. First, by keeping the spraying angle constant, there is not much control on the final geometry of the part being built, and, second, the resultant part’s properties show anisotropy depending on whether this property is measured along the spraying axe or not. In this work, we present a method (Metal Knitting) that aims to help reduce both disadvantages. Metal Knitting is based on the performance of certain spraying movements that build near squared shapes step-by-step like in a knitting process. The principle of the method and examples are presented in this work, as well as some results on the anisotropy of 316L stainless steel freeform parts obtained by CSAM, measuring the tensile stress, hardness, and evaluating the microstructure in different directions of the material. The effect of annealing on the material properties is also investigated.
