JFE TECHNICAL REPORT

No.20 March 2015 - Special Issue on “Steel Plates” and “Welding and Joining”

Application of Narrow Gap Welding Process with “J-STARTM Welding” to Shipbuilding and Construction


SUMI Hiroyuki      KATAOKA Tokihiko      KITANI Yasushi

Abstract

The “J-STARTM Welding” is performed with an electrode negative polarity in CO2 gas shielded arc welding using rare earth metal added wire. In the “J-STARTM Welding,” a conical arc plasma is formed from the wire tip and the droplets that transfer to molten pool become fine and continuous, which called “spray transfer.” As a result, reduction of spatter and deep penetration can be obtained. In the narrow gap welding of thick steel plate, it is necessary that spatter doesn’t accumulate on the welding nozzle and the groove sidewall, and the bottom corner and sidewall of the groove are melted stably. Therefore, narrow gap welding utilizing the benefits of the “J-STARTM Welding” was examined, and a new narrow gap welding process by 2-pass one-layer technique using an electrode with curved tip was developed. It was confirmed that the good joint of 100 mm plate in thickness for which the developed narrow gap welding process is applied can be produced with a very few welding processes of 31 passes and 16 layers.

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