Residual Stress Evaluation in Vitreous Enameled Steel Sheets by Digital Images Analysis of Microstructures

Composite vitreous-enameled steel sheet have become more attractive for structural applications. In this chapter, an investigation on the residual stresses, introduced during the manufacturing of these materials, is reported. The local structure evidences the presence of bubbles in the coating and the interface domain between the substrate and the external layer made of a complex material system where the ceramic and the metal constituents are mixed. This particular local structure can affect the distribution and entity of the residual stresses. Digital images of cross-section micrographs have been processed and used to discretize the material microstructure into a mesh suitable for finite element analysis. The residual stresses have been evaluated on coatings manufactured with different technologies and, in particular, the effect of the presence of bubbles on the stresses has been highlighted.