Numerical analysis of residual stresses induced by cold spray fabricating cBN-reinforced Ni matrix composites

Abstract

Metal particles used as cold spraying feedstock undergo severe plastic deformation during application. During this process, residual stresses are generated. The presence of porous metal particles and ceramic particles further complicates the deformation process. Numerical models have been proposed to describe the formation process for residual stresses induced by cold spray fabricating cBN-reinforced Ni matrix composites on a 42CrMo substrate. The feedstocks to be sprayed are mixtures of porous Ni particles and Ni-coated cBN particles. The analysis of residual stresses for the cBN-reinforced Ni matrix composites was accomplished by depositing cBN particles on the cold-spayed porous Ni particles and multi-layered Ni coatings. Firstly, local residual stresses are generated near the large number of closed pores inside the cold-sprayed porous Ni particles. Simultaneously, the residual stresses at the bottom of the multi-layered Ni coatings are changed from a compressive stress state to a tensile one as the number of cold-sprayed Ni layer increases. Finally, the deposited cBN particles aggravate the transformation of residual stresses during the cold spraying fabrication of multi-layered cBN-reinforced Ni matrix composites. The concentrated compressive stresses are generated when the cBN particles are deposited on the Ni particles. Understanding these phenomena may provide a guideline for tailoring the residual stresses for cold-sprayed cBN-reinforced Ni matrix composites and thereby improve service performance.