Radioactively labelled particle tracking in steel castings

It is well established that non-metallic inclusions are detrimental to the mechanical properties of metals. However, the movement of such inclusions during filling and solidification of a casting is difficult to determine experimentally. This paper describes the development of a technique by which the movement of inclusions can be tracked. Alumina particles of size 355-425 μm were radioactively labelled using a cyclotron and placed on a steel mesh at the entry of a ceramic shell mould. A low carbon steel was cast into the moulds and, after the casting had solidified, the position of the radioactive particle was determined using a y-ray positron camera. The co-ordinates of the particle within the casting were obtained to an accuracy of ± 2-3 mm. This technique has been shown to be a valuable tool for any application where the presence of inclusions is critical.