Use of pre-oxidation to improve reactive wetting of high manganese alloyed steel during hot-dip galvanizing

Nanoscale analysis of the influence of pre-oxidation on oxide formation and wetting behavior of hot-dip galvanized high strength steel

“…These Mn based oxides were found to hinder the growth of a continuous Zn layer on the steel surface during galvanizing [21]. http However, there are some approaches to improve the wettability of high Mn steel with Zn: Blumenau et al [22] suggest an additional pre-oxidation step in order to create a Mn/Fe mixed oxide on the steel surface. The Fe in the mixed oxide should then chemically be reduced during the annealing process by an extremely dry atmosphere and form an Fe 2 Al 5 inhibition layer with the dissolved Al from the liquid Zn bath on top of the MnO, allowing the growth of the Zn layer.…”

“…The aim of our present work is the validation of the existing pre-oxidation approach [22] on a comparable high Mn steel and the verification and improvement of the existing model. We use Auger electron spectroscopy as the main analytical tool because it combines the excellent lateral resolution of scanning electron microscopy (SEM) with the superb determination of chemical compounds known from X-ray photoelectron spectroscopy (XPS).…”

“…We use Auger electron spectroscopy as the main analytical tool because it combines the excellent lateral resolution of scanning electron microscopy (SEM) with the superb determination of chemical compounds known from X-ray photoelectron spectroscopy (XPS). Our experience has shown that chemical analyses of surfaces using coarse methods such as XPS, X-ray diffraction (XRD), glow discharge optical emission spectroscopy (GDOES), energy dispersive X-ray spectroscopy (EDX) and even transmission electron microscopy (TEM) combined with electron energy loss spectroscopy (EELS) may yield misleading results, because these techniques have a high volume interaction [22][23][24]26,27]. If the analyzed surface or interface is not homogeneous, the data obtained from different areas mix and interfere.…”

Direct In-Situ Investigation of Selective Surface Oxidation During Recrystallization Annealing of a Binary Model Alloy

“…By protecting the analyzer via differential pumping from too high pressures, the sample may be exposed to pressures up to several millibars or even higher while still reasonable signal intensities are obtainable. Here we show first results of the application of APPS for the investigation of the high temperature reactions occurring on the surface of a Fe-Mn model alloy during a thermal annealing process that is typical for the so called recrystallization annealing (see [5][6][7][8][9]). The re-crystallization annealing step serves to control the final grain structure and thereby the final mechanical properties of the steel.…”

“…[5,8]). By adjusting the annealing atmosphere, increasing the partial water pressure or lowering the hydrogen partial pressure, respectively, the external (surface) oxidation can be suppressed and intense work is carried out to optimize these conditions [5,9]. As pointed out above, not much information, however, is obtainable for the processes during the high temperature annealing itself.…”