Numerical Analysis of the Heating Characteristics of Magnetic Oscillation Arc and the Fluid Flow in Molten Pool in Narrow Gap Gas Tungsten Arc Welding

Xiaoxia Jian,Xing Yang,Hebao Wu,Weihua Wang,Jingqian Li

doi:10.3390/ma13245799

Abstract

Magnetic oscillation arc (MOA) technology was developed to avoid insufficient fusion defects appearing at the sidewalls in narrow gap gas tungsten arc welding (NG-GTAW). In this work, a unified model was developed to simulate the process of MOA assisted NG-GTAW. The model included the MOA, welding pool, workpiece and the coupling interaction between them. The heating characteristic of the MOA and the flow of liquid metal were simulated, and the mechanism of forming a uniform welding bead under MOA was investigated. It was found that if the magnetic flux density increased to 9 mT, the MOA could point to the sidewall directly; the maximum heat flux at the bottom declined by almost half and at the side, it increased by more than ten times. Additionally, the heat flux was no longer concentrated but dispersed along the narrow groove face. Under the effect of MOA, there were mainly two flow vortexes in the molten pool, which could further increase the heat distribution between the bottom, sidewall and corner, and was beneficial for the formation of a good-shape weld. The model was validated by experimental data.

Highlights

Narrow gap welding is an important joining technology for thick plate structures and is widely used in ship and pipeline manufacturing, the nuclear power industry and so on [1]
Compared with traditional arc welding, in the narrow gap welding process, the gap of the groove is decreased, which can lead to advantages of lower heat input, less filler metal and higher efficiency
Dong studied the theoretical foundation of process design for narrow gap gas tungsten arc welding and pointed out that the heat efficiency of the welding arc was different during weaving [7]

Summary

Introduction

Narrow gap welding is an important joining technology for thick plate structures and is widely used in ship and pipeline manufacturing, the nuclear power industry and so on [1]. Compared with traditional arc welding, in the narrow gap welding process, the gap of the groove is decreased, which can lead to advantages of lower heat input, less filler metal and higher efficiency. Some narrow gap welding methods have been developed to solve this problem, such as rotating arc [3], swing arc [4] and tandem arc welding [5], and so on. Dong studied the theoretical foundation of process design for narrow gap gas tungsten arc welding and pointed out that the heat efficiency of the welding arc was different during weaving [7]

Objectives

Results

Conclusion