Theoretical prediction of residual stresses induced by cold spray with experimental validation

Abstract

Purpose-This study aims to develop a simple analytical model for predicting the throughthickness distribution of residual stresses in a cold spray deposit-substrate assembly. Design/methodology/approach-Layer by layer build up of residual stresses induced by both the peening dominant and thermal mismatch dominant cold spray processes, taking into account the force and moment equilibrium requirements. The proposed model has been validated with the neutron diffraction measurements, taken from the published literature for different combinations of deposit-substrate assemblies comprising Cu, Mg, Ti, Al and Al alloys.Findings-Through a parametric study, the influence of geometrical variables (number of layers, substrate height and individual layer height) on the through-thickness residual stress distribution and magnitude are elucidated. Both the number of deposited layers and substrate height affect residual stress magnitude, whereas the individual layer height has little effect. A good agreement has been achieved between the experimentally measured stress distributions and predictions by the proposed model. Originality/value-The proposed model provides a more thorough explanation of residual stress development mechanisms by the cold spray process along with mathematical representation. Comparing to existing analytical and finite element methods, it provides a quicker estimation of the residual stress distribution and magnitude. This paper provides comparisons and contrast of the two different residual stress mechanisms: the peening dominant and the thermal mismatch dominant. The proposed model allows parametric studies of geometric variables, and can potentially contribute to cold spray process optimisation aiming at residual stress control.

Effect of Post-Deposition Solution Treatment and Ageing on Improving Interfacial Adhesion Strength of Cold Sprayed Ti6Al4V Coatings

“…For example, adhesive-free methods based on [13,[15][16][17] require a much thicker coating (~5 mm) and post-deposition machining to get desired dimensions. Coatings with such a high thickness induce high residual stresses and may cause interfacial cracks or delamination [11,20,27,28]. Moreover, post-deposition machining of the test specimens itself can be a challenge, especially for the CS deposited Ti alloys which is generally very hard and brittle.…”

Evaluation of residual stresses induced by cold spraying of Ti-6Al-4V on Ti-6Al-4V substrates

“…Residual stresses induced by the CS process have been investigated by many researchers for various combinations of deposit-substrate materials comprising Cu, Mg, Ti, Al and Al alloys [11]. Based on previous studies [10][11][12][13][14], residual stresses induced by CS processes can be classified into the peening dominant and thermal mismatch dominant mechanisms. However, there are limited literature on residual stresses induced by cold spraying of titanium and its alloys.…”

Post-Process Treatments on Supersonic Cold Sprayed Coatings: A Review

“…It has been reported by Boruah et al [22] that cold sprayed Ti6Al4V deposits generally started to delaminate after reaching a certain thickness due to the fact that tensile residual stresses were at the top and bottom of the specimen, and compressive stresses were near the interface. Residual stress induced by the cold spray process has been investigated by researchers for various materials from both numerical and experimental aspects [47,[67][68][69][70]. Shot peening is a mechanical surface treatment in which peening media with sufficient hardness and velocity impact with the work piece surface to cause a surface plastic deformation [71], thus producing a cold-worked material with a high stress in compression.…”