IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) e-ISSN: 2278-1684,p-ISSN: 2320-334X, Volume 13, Issue 3, Ver. I (May- Jun. 2016), PP 94-113 www.iosrjournals.org DOI: 10.9790/1684-13030194113 www.iosrjournals.org 94 | Page Analysis of Hardness in Metal Inert Gas Welding Of Two Dissimilar Metals, Mild Steel & Stainless Steel Sharmistha Singh, Neha Gupta Department of Mechanical Engineering Babu Banarasi Das National Institute of Technology and Management/ A. K. T. U. , Lucknow, India Abstract : The aim of my work is to study the hardness that affects the welding joint of dissimilar metals. Stainless Steel 304 was welded to mild steel using a metal inert gas welding which also known as gas metal arc is welding with the help of filler wire of stainless steel and 0.8 0mm diameter. Argon gas was used as shielding gas in this process. Dissimilar metals welding have great scope in advanced technology nowadays owing to their high hardness, high strength and corrosion resistance properties. The combination of mild steel and austenitic stainless steel has got large number of application in industry such as power plant, nuclear plant, and heat exchanger assembly etc. Due to the fact that low cost of mild steel and corrosion resistance property of stainless steel. All these application requires welding of the two which can perform the desired service requirement of the industry. The difference in the properties such as melting point, thermal conductivity, carbon content difference makes austenitic stainless steel and mild steel difficult to weld and gives rise to various failures in the future service life. The results indicate the optimum value of current and voltage which will be applied to developed weld for maximum hardness of welded mild steel and stainless steel 304 specimens . I. Introduction Welding is a fabrication process used to join materials, usually metals or thermoplastics, together. During welding, the pieces to be joined (the work pieces) are melted at the joining interface and usually a filler material is added to form a pool of molten material (the weld pool) that solidifies to become a strong joint. In contrast, Soldering and Brazing do not involve melting the work piece but rather a lower-melting-point material is melted between the work pieces to bond them together. A. Types of Welding There are many different types of welding processes and in general they can be categorized as: B. Arc Welding A welding power supply is used to create and maintain an electric arc between an electrode and the base material to melt metals at the welding point. In such welding processes the power supply could be AC or DC, the electrode could be consumable or non-consumable and a filler material may or may not be added. The most common types of arc welding are: C. Shielded Metal Arc Welding (SMAW) A process that uses a coated consumable electrode to lay the weld. As the electrode melts, the (flux) coating disintegrates, giving off shielding gases that protect the weld area from atmospheric gases and provides molten slag which covers the filler metal as it travels from the electrode to the weld pool. Once part of the weld pool, the slag floats to the surface and protects the weld from contamination as it solidifies. Once hardened, the slag must be chipped away to reveal the finished weld. Fig 1.1 Figure of Arc Welding D. Gas Metal Arc Welding (GMAW) A process in which a continuous and consumable wire electrode and a shielding gas (usually an argon and carbon dioxide mixture) are fed through a welding gun.