Gas Metal Arc Welding Using Novel CaO-Added Mg Alloy Filler Wire

Minjung Kang,Youngnam Ahn,Cheolhee Kim

doi:10.3390/met6070155

Abstract

Novel “ECO Mg” alloys, i.e., CaO-added Mg alloys, which exhibit oxidation resistance during melting and casting processes, even without the use of beryllium or toxic protection gases such as SF6, have recently been introduced. Research on ECO Mg alloys is still continuing, and their application as welding filler metals was investigated in this study. Mechanical and metallurgical aspects of the weldments were analysed after welding, and welding behaviours such as fume generation and droplet transfer were observed during welding. The tensile strength of welds was slightly increased by adding CaO to the filler metal, which resulted from the decreased grain size in the weld metal. When welding Mg alloys, fumes have been unavoidable so far because of the low boiling temperature of Mg. Fume reduction was successfully demonstrated with a wire composed of the novel ECO Mg filler. In addition, stable droplet transfer was observed and spatter suppression could be expected by using CaO-added Mg filler wire.

Highlights

Weight reduction is becoming an increasingly important issue in the automotive industry, to adhere to global CO2 emission and fuel consumption regulations
The the AZ31-B filler wire could result in fume suppression, and this is more clearly confirmed during the welding, wire was melted a droplet formed at the end and of thethis wire
AZ31 filler wire were compared with generation, the conventional fillertransfer wire

Summary

Introduction

Weight reduction is becoming an increasingly important issue in the automotive industry, to adhere to global CO2 emission and fuel consumption regulations. Previous studies have reported that Mg oxidation and ignition could be controlled and minimized in various ECO Mg alloys during melting [1,2,3,4], and improved mechanical properties and metallurgical characteristics have been reported [5,6,7]. Numerous research studies for fusion welding processes that are more familiar and flexible have been recently published to optimize the fusion welding processes These include gas tungsten arc welding [12,13], gas metal arc welding (GMAW) [14], and laser welding [15,16]. As the source of deposited metal in welds, ECO Mg filler wire dissolved in the weld metal can improve mechanical and metallurgical characteristics as confirmed in autogenous laser welding of ECO Mg alloy [19]. Various mechanical and metallurgical characteristics of welds are explained, and welding phenomena such as fume generation and droplet transfer monitored during GMAW will be discussed

Experimental Setup

Welding

Metals

Fume and Droplet Transfer

High-speed images during the cold-metal-transfer mode welding:

Conclusions