MIG and TIG Joining of AA1070 Aluminium Sheets with Different Surface Preparations.

Elisa Fracchia,Róbert Bidulský,Marco Actis Grande,Jana Bidulská

doi:10.3390/ma15020412

Elisa Fracchia, Róbert Bidulský + Show 2 more

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https://doi.org/10.3390/ma15020412

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Abstract

In this work, AA1070 aluminium alloy sheets are joined using TIG and MIG welding after three different edge preparations. Shearing, water jet and plasma-cut processes were used to cut sheets, subsequently welded using ER5356 and ER4043 filler metals for TIG and MIG, respectively. Mechanical properties of the obtained sheets were assessed through tensile tests obtaining a relation between sheet preparation and welding tightness. Micro-hardness measures were performed to evaluate the effects of both welding and cutting processes on the micro-hardness of the alloy, highlighting that TIG welding gives rise to inhomogeneous micro-hardness behaviour. After tensile tests, surface fractures were observed employing scanning electron microscopy to highlight the relation between tensile properties and edge preparations. Fractures show severe oxidation in the water jet cut specimens, ductile fractures and gas porosities.

Highlights

The applications of aluminium alloys are mainly related to their excellent mechanical properties, corrosion resistance and lightweight [1]
Filler metal ER5356 was used in the form of a rod to perform tungsten inert gas (TIG) welding, while filler metal ER4043 in the form of wire was adopted in metal inert gas (MIG) welding
The present work studied the effect of the different cutting processes on welded joints’ microstructures and mechanical properties

Summary

Introduction

The applications of aluminium alloys are mainly related to their excellent mechanical properties, corrosion resistance and lightweight [1]. Al alloys have a low melting point and high thermal conductivity [2]. These properties induce manufacturers to use aluminium alloys for many different purposes. Aluminium alloys are weldable by arc welding, resistance welding and friction stir welding processes [3]. Tungsten inert gas (TIG) or metal inert gas (MIG) are commonly used. Various parameters affect the welding of aluminium alloys, such as the thermal cycle, the specific welding process, the metal’s thickness, the metal’s thermal conductivity and the possible preheating before starting welding. Various precautions, such as proper edge preparation and careful choice of filler metal, are crucial to realize a metallurgical joint free of defects

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