CastScan: High energy tomography for continuous casting of metals

The goal of CastScan is the development of a real-time, non-invasive solidification sensor for the metal casting industry. In metal casting processes, there always exists a solidification front, or liquid-solid interface, the shape and stability of which determines the production rate and quality and has a significant economic impact. Current technologies for monitoring the shape and position of the solidification front have their limitations. We have built a tomographic imager, which we have used to determine the shape of the liquid-solid interface in solidifying aluminum. The operating principle of the sensor is based on the density change between liquid and solid which ranges from 4% to 12% for most metals. For high energy x-rays, the absorption is essentially dependent only on the density of the material. The system includes a 6 MeV compact linac and a 128 element detector array. Typical spatial resolutions are ∼1.6 mm with a density precision of ∼2%