The effect of process parameters on residual stresses within an Inconel 718 part produced by the direct laser deposition process

The residual stress fields generated within a laser deposition metal component or added feature have the potential to significantly affect its properties and performance. Stresses play a major role in determining the initial levels of distortion, in both the added part and the initial substrate material, and affect both short-time properties, such as ductility, and long-time properties, such as creep and corrosion resistance. Their control is therefore essential for the production quality demanded in high performance aerospace components. In this work, a series of geometrically simple components was additively manufactured from Inconel 718 powder using a coaxial diode laser deposition system under a range of process parameters. The residual surface stresses arising were measured using x-ray diffraction techniques and the variations in them with surface position and process parameters are shown. The formation of these stresses and their relationship to Direct Laser Deposition process parameters are discussed.