Residual stress in HVOF thermally sprayed thick deposits

yDue to the nature of the high velocity oxy-fuel thermal spray process, residual stress build up in thick deposits is a significant and a limiting problem. The residual stress-state that evolves in a deposit is largely dependent on the thermal conditions to which the system has been subjected, and is a combination of quenching stresses, which arise during deposition, and cooling stresses, post-deposition. It follows that precise control of these phenomena is essential, if a thick deposit is to be thermally sprayed. This paper applies an analytical technique to calculate residual stress in thermally sprayed deposits based on geometric properties. Residual stress results for WC-Co (tungsten carbide-cobalt) samples are compared to experimental results (X-ray diffraction and hole-drilling method). A change in deposit stress-state from tensile to compressive stress with deposit thickness is analysed in terms of quenching and cooling stresses. (C) 2003 Elsevier B.V. All rights reserved.