Microstructure and Erosion-Corrosion Behavior of Hot-Dipping Al-Mn Alloy Coatings on Low Carbon Steel

Abstract

Low carbon steel was coated by hot-dipping into a molten bath containing Al-2 wt.%Mn. The phase composition, morphology and the erosion-corrosion behavior of the aluminide layer were characterized by XRD, OM, SEM and erosion-corrosion tester, respectively. The results show that the coatings are mainly composed of Al, FeAl3, Fe2Al5 and MnAl6 phase. The coatings consist of two-layer structure, i.e., toplayer Al-Mn alloy layer and tongue-like intermetallic compound. The thickness of the coating layer is about 800 μm and all the coating layers show good adhesion to the steel substrate. Compared with the pure Al coatings, the Al-Mn alloy coatings exhibit lower wear rate irrespective of the rotation speed. The hot-dipped Al-Mn coatings possess considerable erosion-corrosion resistance.