Effects of carbon content of carbon steel on its dissolution into a molten aluminum alloy

Hot dip aluminizing of carbon steels with different carbon concentration ranging 0.2-1.1 wt.% was carried out in a molten Al-9.08 wt.% Si-0.98 wt.% Fe alloy at 660 °C. The steel specimens lost weight as a result of dissolution into the melt, and an intermetallic layer was formed on the surface of them. The specimens showed varied dissolution rates depending on carbon concentration. The specimen with the highest carbon content exhibited the slowest dissolution rate. The thickness of the intermetallic layer increased with dipping time following a parabolic relationship. The growth rate of the layer decreased with increase of the carbon content. A diffusion mechanism to control the dissolution of the carbon steel into the molten aluminum alloy was suggested, and the effect of carbon content on the dissolution of the steel substrate into the melt was discussed in connection with the proposed diffusion mechanism and microstructural observations.