Influence of Inhibition Layer on Adhesion of a Galvanized High Al Dual Phase Steel

The morphology of inhibition layer and adhesion of Zn coating about a 600MPa grade high Al dual phase steel were studied by grow discharge spectrometry (GDS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the inhibition layer is mainly composed of Fe 2 Al 5-x Zn x particles with a size of 0.5~1μm, and the adhesion is directly related to the density of the inhibition layer, the denser the inhibition layer, the better the adhesion. It is found: for the samples with good adhesion that besides the Fe 2 Al 5-x Znx particles, there are also some small spherical Al-Mn oxides particles in sizes from 30 to 100nm uniformly distributed in the inhibition layer; for the samples with bad adhesion, the steel substrate is not fully covered by Fe 2 Al 5-x Zn x particles and large amount manganese oxides are detected at the non-covered positions.