Characterization of ferritic ductile iron subjected to successive aluminizing and austempering

Abstract

In this study, GJS-500-14 solution-strengthened ferritic ductile iron was subjected to successive hot-dip aluminizing (HDA) and austempering. The combination of these processes resulted in the formation of a thin Al2O3 layer on the iron surface, an intermetallic layer beneath the surface, and an ausferritic microstructure in the interior. Scanning electron microscopy-energy dispersive X-ray spectrometry and X-ray diffraction analyses allowed the qualitative identification of the intermetallics formed due to the aluminizing and their transformation after austempering. Corrosion properties of the final product were also evaluated by potentiodynamic polarization and salt spray corrosion tests, and the surfaces and subsurfaces of the coating layer were examined. The results revealed that this combined process improved the corrosion resistance of ductile iron and enhanced its mechanical properties.