Classification of AE signals for monitoring martensite formation from welding

Welding of high-carbon and some high-hardenable alloy steels often can cause martensite formation, which may lead to cold cracks. Acoustic emission is one of the most promising techniques for monitoring martensite formation, since it can be implemented in real time with a remote sensor, and is highly sensitive and nondestructive. In this paper, martensitic transformation occurring during welding of AISI 4340 steel is identified from signals from porosity and sound welds using pattern recognition analysis of the acoustic emission signals generated