Changing oxide layer structures with respect to the dew point prior to hot-dip galvanizing of δ-TRIP steel

Low-carbon, low-alloy δ-TRIP steel is a research topic of interest because it meets the lightweight requirements of automotive steel. To bolster its use as automotive steel, the present study focused on the galvanizing process of δ-TRIP steel. Samples were submitted to simulated annealing prior to hot-dip galvanization. The surface morphology of five groups of samples marked with different dew points were detected using scanning electron microscopy (SEM). The element distribution in the oxide layers of four groups of samples were detected using glow discharge optical emission spectroscopy (GDOES), and oxide layer structures of two representative groups of samples were analyzed using transmission electron microscopy (TEM) techniques. The results showed that the dew point affected the oxide layer structure of δ-TRIP steel. Increasing the dew point led to an extraordinary oxide layer of pure overflowing Fe platelets in the δ-TRIP steel. The present study is expected to prompt further developments in galvanized δ-TRIP steels.