Practical Application of Acoustic Emission Detection for Welding Process (Report 3)

Classification of AE Signal from Hot Cracking and Others Noise Signal

Abstract

In previous work, the detected shapes and frequency spectra of AE signals were distinguished from AE signal of hot cracking and arc noise in the frequency band of DC to 400 kHz. This work was carried out to distinguish the all of these AE signals from hot cracking test during TIC welding for SUS 310S stainless steel with the AE monitoring system added data recorder and analyzed fully the AE signals in the frequency band from 290 Hz to 320 kHz.
The shape of AE signal from hot cracking had a larger amplitude than the sound of friction and the one of arc noise, and its frequency spectra had the A type shape which had 2 or 3 peaks in the frequency band from 290 Hz to 320 kHz. Fracture surface of hot cracking consist of dendritic boundaries and divided into two region of liquidus phase and solidus phase in just welding. The fractographic observation confirmed that the histogram of the A type of AE signal correspond closely to the area of solidus phase region. Therefore, the A type of AE signal generated at hot cracking.
The shape of AE signal generated from friction had smaller amplitude and its frequency spectra consist of same level in a continuous freouencv bands between 290 Hz and 320 kHz.
The shape of AE signal from arc noise was recognized small amplitude like as a sine curve and its frequency spectra had single frequency component at about 150 kHz.
Further the system added data recorder will be successfully applied to classify the AE signal from weld sounds including hot cracking and arc noise by AE signal and frequence spectra and monitored the hot cracking for welding process.