Abnormal grain in an aluminum alloy

1. Static and Dynamic Abnormal Grain GrowthEric M. Taleff, The University of Texas at Austin, DMR 0605731 Metals and alloys used in structural applications, such as the frame and body of an automobile, are composed of many small crystals, called grains. The size and shape of these grains strongly affect material strength and other important properties. During elevated-temperature processing of these materials into useful parts, some grains can grow to very large sizes, which diminish strength. These are called abnormal grains. We have discovered that growth of abnormal grains can occur by two categories of processes, static growth and dynamic growth. We have further identified a mechanism by which abnormal grains grow in a deformed material. This new understanding allows us to control and prevent abnormal grain growth under many different conditions. Abnormal grain in an aluminum alloy A schematic illustrating how seeds (red) for abnormal grains form in a deformed grain.

2. Metals Science to Improve Automobile EfficiencyEric M. Taleff, The University of Texas at Austin, DMR 0605731 (a) Abnormal grain growth is a problem critical to the hot forming of vehicle components in light-weight materials. Light-weight components significantly increase vehicle efficiency by reducing vehicle mass. The ability we have developed to predict, control and prevent abnormal grains in hot forming will enable production of improved light-weight vehicle components at lower cost. Industrial Collaborators: General Motors Corp. Furukawa-Sky Aluminum Corp. Nippon Steel Corp. (b) Light-weight aluminum components produced by hot forming: (a) Cadillac STS trunk (courtesy of GM Corp.) and (b) Acura RL subframe component.