Residual stresses and crystallographic texture in hard-chromium electroplated coatings

Abstract The X-ray diffraction method was used to study the structural and mechanical state of etectrodeposited chromium coatings. Experiments were performed on layers of various thicknesses, plated on different types of substrates, and the evolution of the stress state as a function of depth was studied. The dependence of the texture on the thickness of the coatings and the substrate material was also studied. The effects of the texture on the values of the X-ray elastic constants (XEC) were taken into account using the orientation distribution function (ODF) or the crystallites group method. The elastic behaviour of the diffracting domains was studied in 3 ways: using the anisotropic self-consistent Kroner-Eshelby model, assuming Reuss' hypothesis, and considering the isotropic case. Final values of residual stresses are compared and a simple method of evaluation is proposed. The chromium deposits were plated by direct current. They are very cracked and exhibit a fibre texture with a 〈111〉 axis. The residual stresses are tensile with values about 800 MPa at the surface, decreasing with depth according to the thickness of the layer, and increasing again at the coating-substrate interface.