The residual stress state in thermal sprayed coatings plays an important role when adhesion and cohesion reliability is involved. In HVOF, in addition to the usual quenching and thermal mismatch stresses, one also observes peening stresses associated with particle impact at high velocitites (600-800 m/s). The peening effect induces compressive stresses due to strain hardening of the substrate and deposited layers. Competition among tensile stresses (due to quenching) and compressive stresses (due to peening) is present during spraying. Peening effect occurs between subsequent layers and among the layer itself.

In this study, the dynamic evolution of residual stresses is studied by insitu curvature sensing. The particle state, materials (strain-hardening characteristic) and the feedrate are varied to evaluate their effect on the induction of peening and quenching stresses. Residual stress results by curvature are compared to X-ray diffraction and through thickness neutron diffraction measurements. Special attention is given to the residual stress state generated in the substrate-coating interface and its potential effect on the fatigue failure.