7Malin V Y. State of the art of narrow gap welding[ J ]. Weld- ing Journal, 1983, 62(6) : 22 -30.
8Kang Y H, Na S J. Characteristics of welding and alx: signal in narrow groove gas metal arc welding using electromagnetic arc oscillation[J]. Welding Journal, 2003, 82 (S5) : 93 - 99.
