Microstructure and mechanical properties of Al-alloyed ductile iron upon casting and austempering

Abstract

In the current study, Al was added to ductile iron (DI) in the range of 0·68–2·70 wt-% and its influence on the mechanical properties and on the microstructure at different section thicknesses was investigated. It was observed that increasing Al addition up to 2·70 wt-% improves the hardness and strength in the as-cast condition. However, this effect was completely reversed after austempering, where the mechanical properties decreased gradually with increasing Al content. In conclusion, Al reduced the strength of DI after austenitising at 900°C. Higher austempering temperatures may be required to achieve the desired properties depending on the Al content of the as-cast DI.