Detection of solidification cracking of Al-7mass%Si alloy by using acoustic emission and visualization methods

Detection of AE signals of solidification cracking of Al-7mass%Si alloy was attempted with in situ microscopic observation on the surface of casting using high speed camera. During solidification, it was found that AE signal from the casting with crack was higher than AE signal from the casting without crack. As a result of observation of casting using high speed camera, it was found that a rise of AE signal corresponded to initiation of solidification cracking. This stage was the stage of eutectic solidification. Thus, AE signals of solidification cracking should be generated during eutectic solidification. However, AE signals from the casting without cracking were also detected during solidification. This means that AE signals other than solidification cracking should be generated during solidification. Therefore, AE signals detected during eutectic solidification is not necessarily AE signals of solidification cracking. In order to detect AE signals of solidification cracking, it is necessary to separate AE signals of solidification cracking and other than solidification cracking.