Fatigue behavior and FEM modeling of thin-coated components

Physical vapor deposition (PVD) surface coatings make it possible to increase the surface hardness of treated components. Despite the good wear resistance of such coatings, the fatigue behavior of the bulk material may be affected by changes in the residual stress field and microhardness. The two-fold aim of this paper is to characterize the fatigue behavior of thin-coated components and to develop a model for fatigue life prediction. The fatigue behavior characterization was carried out by means of four-point bending tests, while the microstructure of the bulk and coating materials was evaluated by means of SEM analysis, microhardness and residual stress measurements. Equipment with which to carry out the four-point bending tests was specially designed for the purpose. Numerical FEM models of the specimens used in the experimental tests were developed with the aim of giving the designer a useful tool with which to predict the fatigue behavior of thin-coated components. Experimental tests carried out on duplex stainless steel coated with CrN PVD coating (5 μm thickness) validate the numerical model.