Finite Element Analysis of the Interfacial Debonding of the Galvannealed Coating Layer with High Tensile Strength Steel Substrates

For energy saving, it is planned to use galvannealed high strength steels for the car body materials. However, the influences of the high strength steel substrate on the fracture behavior of the coating layer and interfacial debonding behavior have not been revealed yet. In the present work, numerical analysis using a finite element method was carried out. It was revealed that (i) the higher the tensile strength of the substrate, the shorter becomes the crack spacing of the coating layer and (ii) the less interfacial debonding takes place in high strength substrate steels due to the short crack spacing, as long as the coating layer- and interfacial bonding-strengths of high strength substrate samples are the same as those of low strength ones.