Effect of cryogenic cooling on residual stresses and surface finish of 316L during hybrid manufacturing

The use of additive manufacturing (AM) has increased significantly in recent years, primarily to produce critical and small components with complex geometry that cannot be manufactured through conventional processes. The application of a secondary process, such as machining, improves the surface finish and alters the residual stresses generated during the AM process. The objective of this study was to investigate the effect of different types of cutting fluids on the machined surface roughness and residual stresses of components produced through AM and conventional rolling processes of AISI 316L. A carbide tool was used during the milling process, and three types of cutting fluids were examined: dry machining, flooded cutting fluid, and cryogenic cooling. Residual stresses were evaluated using X-ray diffraction, while surface roughness was determined using an interferometer microscope. The surfaces were also analyzed through scanning electron microscopy (SEM). The best results for surface roughness and residual stress were achieved with the use of cryogenic cooling, with SEM revealing the presence of adhered material particles on the surface. A correlation was established between residual stress and surface kurtosis roughness, represented by the R KU parameter, and the increase in kurtosis could be associated with an inversely proportional increase in the parallel residual stress. This study provides valuable insights into the impact of the cutting fluid type on the quality of the surface and residual stress of machined components produced through AM and conventional rolling processes. Graphical abstract