가변 극성 알루미늄 아크 용접의 초고속 카메라 음극점 현상 관찰 (Cathode Spot Phenomena Observation by High Speed Camera in Variable Polarity Aluminum Arc Welding)

서지정보

· 발행기관 : 대한용접접합학회
· 수록지 정보 : 대한용접접합학회지 / 36권 / 1호 / 103 ~ 107페이지
· 저자명 : 조정호, 정훈철, 박경배, 이준경

초록

Variable polarity GTAW is applied to aluminum alloys for the purpose of low heat input and thermal deformation.
Reverse polarity plays a role of removing oxide film then enhances the arc weldability of aluminum.
However, it is newly known that reverse polarity also increases heat input efficiency in arc welding. The authors explained the phenomenon by adopting combination of cathode spot random walk and quantum tunneling effect. In this research, stationary variable polarity GTA is observed through high speed camera to figure out the characteristics of cathode spots of aluminum surface in reverse polarity and prove heat input increase effect. As result, anode spot is not observed during straight polarity in variable polarity arc unlike straight polarity DC arc because the oxide layer is removed then the electrons are widely absorbed.
Cathode spots are observed on the aluminum surface during reverse polarity duration in variable polarity arc. Several spots are generated in simultaneously and their locations are quickly changed, which is even faster than frame rate of high speed camera. Occasionally one big cathode spot is generated then arc plasma is concentrated on the spot. As result, spatters and metal vapor are observed in the vicinity of the spot because of the concentrated arc plasma on very small area, which is not observed in straight polarity arc in DC or variable polarity.

영어초록

Variable polarity GTAW is applied to aluminum alloys for the purpose of low heat input and thermal deformation.
Reverse polarity plays a role of removing oxide film then enhances the arc weldability of aluminum.
However, it is newly known that reverse polarity also increases heat input efficiency in arc welding. The authors explained the phenomenon by adopting combination of cathode spot random walk and quantum tunneling effect. In this research, stationary variable polarity GTA is observed through high speed camera to figure out the characteristics of cathode spots of aluminum surface in reverse polarity and prove heat input increase effect. As result, anode spot is not observed during straight polarity in variable polarity arc unlike straight polarity DC arc because the oxide layer is removed then the electrons are widely absorbed.
Cathode spots are observed on the aluminum surface during reverse polarity duration in variable polarity arc. Several spots are generated in simultaneously and their locations are quickly changed, which is even faster than frame rate of high speed camera. Occasionally one big cathode spot is generated then arc plasma is concentrated on the spot. As result, spatters and metal vapor are observed in the vicinity of the spot because of the concentrated arc plasma on very small area, which is not observed in straight polarity arc in DC or variable polarity.

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