Weldability Increase of Aluminum by Variable Polarity Arc

Cho, Jungho

doi:2014.32.1.108

J Weld Join > Volume 32(1); 2014 > Article

Research Paper

Journal of Welding and Joining 2014;32(1):108-111.
DOI: https://doi.org/10.5781/JWJ.2014.32.1.108 Published online February 27, 2014.

Weldability Increase of Aluminum by Variable Polarity Arc

Jungho Cho

Correspondence: Jungho Cho,
Email: junghocho@chungbuk.ac.kr

Abstract

Low arc weldability of aluminum alloy is enhanced by applying variable polarity TIG and the result is theoretically investigated to figure out the mechanism. Conventionally, it is well known fact that DCEP (reverse polarity) arc is effective on aluminum welding. The reason is due to oxide layer removal by plasma ion bombardment and therefore it is named as cleaning effect. Another fact of polarity characteristic is that DCEN shows higher heat input efficiency therefore conventional variable polarity arc used to apply DCEP portion as small as possible. However, higher DCEP portion shows bigger weldment in this research and it is explained by adopting a theory of arc concentration on oxide layer with tunneling effect which was not clearly mentioned before in several variable polarity TIG welding research. Disagreement between variable polarity TIG welding result and conventional arc polarity theory is rationally explained for the first time with help of electron emission theory.

Key Words: Variable polarity, Arc, Aluminum, Weldability, Cleaning effect, GTA, TIG, DCEP