Influence of the bi-material interface on the crack propagation through a thin protective layer

Abstract

Finite element parametric analysis is performed on a cracked bi-material bar subjected to pure bending in order to investigate the fatigue behaviour of a short crack in the thin protective layer laser-cladded on a steel substrate. Elastic properties of the surface layer are chosen with regard to real combinations of materials when bronze, nickel or cobalt alloys are applied as the surface layers to improve the properties of the basic steel substrate and the influence of their mismatch is analysed. Classical linear elastic fracture mechanics theory is applied, and several conclusions are stated that shall help to select a suitable material of the protective layer. The conclusions can be applied analogically to any other bi-material combination.Finite element parametric analysis is performed on a cracked bi-material bar subjected to pure bending in order to investigate the fatigue behaviour of a short crack in the thin protective layer laser-cladded on a steel substrate. Elastic properties of the surface layer are chosen with regard to real combinations of materials when bronze, nickel or cobalt alloys are applied as the surface layers to improve the properties of the basic steel substrate and the influence of their mismatch is analysed. Classical linear elastic fracture mechanics theory is applied, and several conclusions are stated that shall help to select a suitable material of the protective layer. The conclusions can be applied analogically to any other bi-material combination.