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The automotive industry is increasingly looking at stronger and lightweight materials for use in engine production in order to meet forthcoming emissions regulations and increased market competition. In particular, there has been an increasing demand over recent years for thin-wall (<3mm) ductile iron castings to provide components with high strength-to-weight ratios. Reducing the weight of ductile iron castings by producing thin-wall parts is an important method for saving energy and materials, and hence reducing emissions. In production, however, the high cooling rate of thin-section ductile iron results in metallurgical problems of carbide formation, microporosity, and misruns, which adversely affect the machinability and mechanical properties. The production of thin-wall iron castings is presently limited by a lack of metallurgical processing guidelines. The technical challenge is associated both with precise metallurgical process control to produce a carbide-free structure, and with the establishment of good mold filling ability through appropriate casting techniques. The energy requirement for melting iron is much lower than for other alloys, as confirmed by recent energy audits in several Canadian foundries using the Mobile Foundry Laboratory. Therefore, developing and perfecting thin-wall iron casting technology will not only result in weight reduction of the components presently made of iron, but will also provide a viable alternative material for some components that is cheaper and results in less CO 2 emissions from the utilities point of view. The transfer of thin-wall iron casting technology to Canadian automotive parts producers will increase their competitiveness and technical capability to respond to increasing demands for lightweight materials that will lead to lower vehicle weights and reduced emissions.The objective of this research is to develop and advance thin-wall iron casting technology to produce strong, lightweight iron castings at lower cost for automotive applications. In preliminary work done at MTL-CANMET, carbide-free thin-wall (down to 1mm) ductile iron castings with good strength properties were produced by optimizing the chemical composition, post inoculation procedures, and melt pre-conditioning, along with precise control of the melting process and the use of high purity charge materials. Carbide formation was decreased by the use of moldable insulating materials, certain molding systems/binders, and a finer sand grain size. This research has resulted in 7 presentations and 5 publications in refereed journals, and has led to a task-shared project on thin-wall ductile iron castings with Rio Tinto where the mold filling characteristics will be examined using vacuum assisted casting methods.The effect of microstructure achieved under various molten metal processing conditions and melt chemistries on the mechanical properties was investigated. Microstructure evaluation was done (close to the fracture end of test samples) to characterize the graphite count, shape, size, and distribu...

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