Journal of Welding and Joining

The Korean Welding and Joining Society (대한용접접합학회)
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Fundamental Study on the Weld Defects and Its Real-time Monitoring Method

레이저 용접시 용접결함의 실시간 모니터링법 개발에 관한 연구

  • 김종도 (한국해양대학교 기관시스템공학부)
  • Published : 2002.02.01
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Abstract

This study was undertaken to obtain the fundamental knowledges on the weld deflects and it's realtime monitoring method. The paper describes the results of high speed photography, acoustic emission (AE) detection and plasma light emission (LE) measurements during $CO_2$ laser welding of STS 304 stainless steel and A5083 aluminum alloy in different welding condition. The characteristic frequencies of plasma and keyhole fluctuations at different welding speed and shield gases were measured and compared with the results of Fourier analyses of temporal AE and LE spectra, and they had considerably good agreement with keyhole and plasma fluctuation. Namely, the low frequency peaks of AE and LE shifted to higher frequency range with the welding speed increase, and leer the argon shield gas it was higher than that in helium and nitrogen gases. The low frequencies dominating in fluctuation spectra of LE probably reflect keyhole opening instability. It is possible to monitor the weld bead deflects by analyzing the acoustic and/or plasma light emission signals.

Keywords

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