Thick-wire swing arc narrow gap GMA welding assisted by pre-embedding cold wires

Abstract

To raise narrow gap GMA welding efficiency while ensuring weld formation, the present work presents a thick wire swing arc narrow gap GMA welding process assisted by cold wires. This process employs the thick wire and the pre-embedded cold wires to jointly increase the welding efficiency, while improving the groove sidewall penetration by the swing arc. Two types of thick wires, being conventional single-strand welding wire (SWW) and cable-type welding wire (CWW), are respectively used as main wire. After solving the series arc problem during CWW arc-igniting, the effects of the pre-embedded wire layer number on narrow gap weld formation and welding efficiency are investigated for the thick wire welding. Experimental results show that the weld thickness and the sidewall penetration do not obviously change with increasing the number of the cold wires, while the weld layer height significantly grows. Additionally, the SWW weld formation looks more sound. Compared to the thin-wire welding, the thick wire welding without the cold wire raises the deposition rate by about 38% and 58% as respectively using SWW and CWW. When pre-embedding two layers of cold wires, the increased percentage of the deposition rate further rises respectively to about 81% and 112%. These thus demonstrate the effectiveness of the developed process in addition to the higher efficiency of the CWW welding.

Microstructure and Hardness Characteristics of Swing-Arc SAW Hardfacing Layers

“…Its positive and negative terminals are, respectively, connected to the swing-arc torch and base metal. The welding torch [17], including the hollow-shaft motor, bending conductive rod, and straight contact tip, adopts a conductive rod of bending angle β of 10 • to circularly swing the arc at an angular velocity of ω relative to the torch central line OO 2 , the swing trace of which is indicated by the arc-shape line MO 1 D in Figure 1b. Accordingly, arc swing parameters contain swing angle α, swing radius r, and side-dwell time t, respectively, at the left and right limiting points M and D of the swing.…”