On the evolution of substrate's residual stress during cold spray process: A parametric study

A comprehensive study was undertaken to determine the effects of carrier gas temperature, pressure, and nozzle speed on the residual stresses induced by cold spray coating of aluminum 7075 powder onto AZ31B-H24 magnesium substrate. Embedded Fiber Bragg Grating sensors and thermocouples were employed for simultaneous in-situ measurements of strain and temperature during cold spray process. A statistical model was then developed based on the significance and interactions of the cold spray parameters on the residual stress field. This model demonstrated that the induced temperature is the most significant parameter to the final formation of residual stress. It is also shown that the peening effect plus the temperature resulted from the cold spray yields to the dynamic recrystallization of the substrate near the surface, and generates nano-size grains at the interface. This research validates that the final size of the refined grains and the level of induced residual stress depend heavily on the process' thermal energy. (C) 2017 Elsevier Ltd. All rights reserved.