Abstract
In situ measurement of solidification process was attempted by detecting acoustic emission (AE) signals through a wave guide in the final freezing zone of casting which solidified at various freezing conditions and had different types of casting defects such as cavities and hot-tearing. AE signals with remarkable peak voltage which are never detected in the early stage of solidification are detected not only at the end of solidification in all the castings but also in the later stage of solidification in the alloy castings having numerous cavities or remarkable hot-tearing. AE signals accompanied with fracture of solidifying castings at the solid-liquid co-existing state is detectable. These facts mean that formation of cavities or hot-tearing in the solidification process is detectable by a non-destructive, AE signal measurement.
