Effects of alloying elements on surface oxides of hot–dip galvanized press hardened steel
Wolfgang Gaderbauer, Martin Arndt, Tia Truglas, Thomas Steck, Nico Klingner, David Stifter, Josef Faderl, Heiko Groiß
Abstract
The 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, were identified as ZnO and (Mn,Zn)Mn2O4 spinel. For some of the investigated steel alloys, an additional non–uniform, several nanometer thick Cr enriched 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.