Internal Stresses, Texture, and Anisotropy in High-Contraction ElectroplatedChromium Coatings

摘要

Internal residual stresses in refractory coatings of the bore cause cracking,flaking, peeling, and failure of the coatings and substrate. Strong fiber texture, perfect in-plane azimuthal symmetry, low single-crystal anisotropy, and high-surface tensile residual stresses were observed in high-contraction chromium on steel. The conventional d-square of sin(psi) method fails in the evaluation of residual stress if the existence of texture is not taken into account. Elastic moduli were evaluated from single-crystal elastic constants. Two methods were developed to extract residual stresses in textured chromium coatings: (1) A new matlab matrix inversion method using a single family of reflections. The method allows calculation of residual stress and unstrained lattice parameter in textured cubic materials. (2) A Hill-Neerfeld model assuming elastic isotropy. This is a d-square of sin(psi) method adapted to multiple families of reflections.