Investigation of Influence Factors on Residual Stress Determination within Coated Surfaces in Consideration of the Differential and Integral Method

Abstract

Abstract. To improve the surface behavior of metal structures, like wear-and heat resistance or hardness, often thermally sprayed ceramic coatings are applied. A modern technology to realize dense layers is the High Velocity Oxygen Fuel (HVOF) technique. The deposition process and necessary pretreatments can cause high residual stresses within the coating and the substrate. While tensile stresses in the brittle coating may cause cracks, compressive stress states can even improve the materials behavior. To guarantee high product quality, it is necessary to know exactly the occurring residual stresses in the metal-ceramic hybrid system. A very common measurement technique is the incremental hole drilling (IHD) method. To determine the residual stresses out of IHD measurements the differential method (DM) or integral method (IM) can be used. To investigate the influence of interfacial layers, nonlinear stresses, cracking, anisotropy, variation of coating thickness and calculation formalisms several FEM models have been build, while case sensitive calibration was used for the coated systems.

Numerical calculation of temperature and surface topology during a laser ablation process for ceramic coatings

“…In order to determine these stresses it is possible to drill a hole into the component and measure the occurring deformations with strain gauges. These strains can then be recalculated to get the governing depth dependent residual stress [2]. This procedure is called incremental hole drilling and the cut-out is usually imposed stepwise by a mechanical drill.…”

Evaluation of Residual Stress Determinations Conducted with Laser Ablation and Optical Displacement Measurement

“…1). For this determination a mechanical IHD operation was conducted, where an integral method (IM) evaluation scheme with a case sensitive calibration was applied [1]. Further numerical studies showed, that the high values after 200 µm depth might be mainly related to a plastification process due to the stress intensification around the hole.…”