1994 Volume 80 Issue 3 Pages 225-230
We investigated on the shear adhesion strength of galvannealed steel (GA). High adhesion strength of GA with less than 7 mass% Fe, 11 mass% Fe or more was obtained.
A structure of GA coating/substrate interface on adhesion strength was aimed. The observations were carried out by transmission electron microscope (TEM) and scanning electron microscope (SEM). Γ phase remarkably grew at the coating/substrate interface of GA with over 11 mass% Fe. The ledge with pitch of approximately 100nm was formed at Γ/αFe interface. It seems that Γ phase grows by lateral growth mechanism. On the other hand, epitaxy between αFe and Γ phase was not found out. From the above mentioned results, it was proposed as a model that interface adhesion strength of GA was varied with geometrical shape of the interface.