IJSRSET162329 | Received: 11 May 2016 | Accepted: 18 May 2016 | May-June 2016 [(2)3: 172-175] © 2016 IJSRSET | Volume 2 | Issue 3 | Print ISSN : 2395-1990 | Online ISSN : 2394-4099 Themed Section: Engineering and Technology 172 A Comparison of Welding Techniques of Aluminium Alloys A Literature Review Ajay Kumar, Mohammad Shahal Milton Department of Mechanical Engineering, LRIET, Solan, Himachal Pradesh, India ABSTRACT Welding of aluminum alloys is an important issue because of their increasing applications in industries. The most widely used joining methods for aluminium alloys are Tungsten Inert Gas (TIG), Metal Inert Gas (MIG), Variable Polarity Plasma Arc (VPPA) and Friction stir welding (FSW). However, the high conductivity, high reflectivity, high reactivity and high coefficient of thermal expansion make welding of aluminium alloys difficult. In this paper, the research and progress of a variety of welding techniques for joining Al alloys are reviewed. The aim of the paper is to review the recent progress in the welding of aluminium alloys to provide a basis for follow-up research. Keywords: Aluminium alloys, welding techniques, TIG, MIG, FSW. I. INTRODUCTION Aluminium alloys are of particular interest in the design of lightweight fortification structures in applications such as aerospace, defense, locomotive, automotive and in energy sectors. The outstanding properties of aluminium such as low density, high specific strength, high specific energy absorption capability, good corrosion resistance and good thermal conductivity, formability, machinability, their non-magnetic nature and low cost are the reasons for their wide application. As a part of the fabrication process, welding is one of the most important manufacturing technologies used in the aluminum alloy industry. The most widely used joining methods for aluminium alloys are Tungsten Inert Gas (TIG), Metal Inert Gas (MIG), Variable Polarity Plasma Arc (VPPA) and Electron Beam (EB) welding. These processes allow us to obtain optimum mechanical properties with minimum distortion due to the high heat intensities provided by these sources. However, the high conductivity, high reflectivity, high reactivity and high coefficient of thermal expansion make welding of aluminium alloys difficult. The high heat input associated with high thermal conductivity and high coefficient of expansion could lead to severe distortion of parts during welding. Careful control of welding parameters is a must to get a sound weld in aluminum alloys. Compared to the above mentioned fusion welding processes that are routinely used for joining structural aluminium alloys, Friction Stir Welding process is an emerging solid state joining process in which the material that is being welded does not melt and recast. Therefore, when alloys are friction stir welded, phase transformations that occur during the cooling of the weld are of a solid state type. Due to the absence of parent metal melting, the new FS welding process is observed to offer several advantages over fusion welding. Compared to fusion welding processes, there is little or no porosity or other defects related to fusion. In fact, the industrial interest of this study is to evaluate the possible benefits of FSW compared to TIG, MIG considering the lower heat input of the solid-state joining process and the high stability of hardening particles. Weldability of some aluminium alloys is an issue with the fusion welding processes. The 2000 series, 4000 series, 5000 series, 6000 series and 7000 series of aluminium alloys have different weldabilities. The fusion welding of aluminum alloys offered a great challenge for designers. The difficulties associated to welded joints are mainly related to the presence of an oxide layer, high thermal conductivity, solidification shrinkage, high solubility of hydrogen and other gases into molten state. Many researchers have compared fusion welding and solid state welding processes for aluminium alloys and