  Effects of steel alloying elements on the formation of the surface oxide
layer of hot-dip galvanized press hardened steel after austenitization
annealing were examined with various advanced microscopy and spectroscopy
techniques. The main oxides on top of the original thin Al2O3 layer,
originating from the primary galvanizing process, are identified as ZnO and
(Mn,Zn)Mn2O4 spinel. For some of the investigated steel alloys, a non-uniform,
several nanometer thick Cr enriched, additional film was found at the Al2O3
layer. At a sufficiently high concentration, Cr can act as a substitute for Al
during annealing, strengthening and regenerating the original Al2O3 layer with
Cr2O3. Further analysis with secondary ion mass spectrometry allowed a reliable
distinction between ZnO and Zn(OH)2.
