In discussions of sustainable or "green" design, the topic of weight reduction is often the first consideration. Immediately, engineers of structural components turn to materials with low density such as aluminum and magnesium. However, when strength and stiffness are taken into consideration, a low-density material does not always result in a lower mass component or assembly. Further, in the search to propel devices using less fuel energy, engineers can often lose sight of the total life-cycle energy of the material/process combination they have chosen in their design. High strength steels have made great advances, allowing their designs to compete with "lightweight" metals. The steel manufacturers have done a good job communicating "new steel" to the design community. However, the design community is largely unfamiliar with the light weight and low energy properties of Austempered Ductile Iron (ADI). The lure of low specific gravity can lock design engineers into an improper material/process combination early in the design process to the exclusion of other, more efficient material/process combinations. This paper will familiarize the reader with the concept of embodied energy and some of the environmental advantages of converting from a conventional material/process combination to an ADI casting solution.
