IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308 _______________________________________________________________________________________ Volume: 03 Issue: 04 | Apr-2014, Available @ http://www.ijret.org 751 STUDY OF MECHANICAL PROPERTIES IN MILD STEEL USING METAL INERT GAS WELDING Rakesh Kumar 1 , Satish Kumar 2 1 M.Tech scholar, Department of Mechanical Engineering, HCTM Technical Campus, Kaithal, Haryana, India 2 Assistant Professor, Department of Mechanical Engineering, HCTM Technical Campus, Kaithal, Haryana, India Abstract The aim of the present study is to show the influence of different input parameters such as welding current, arc voltage and root gap on the mechanical properties during the Metal Inert Gas Welding (MIG) of mild steel 1018 grade. The microstructure, hardness and tensile strength of weld specimen are investigated in this study. The selected three input parameters were varied at three levels. On the analogy, nine experiments were performed ba sed on L9 orthogonal array of Taguchi’s methodology, which consist three input parameters. Analysis of variance (ANOVA) was employed to find the levels of significance of input parameters. Root gap has greatest effect on tensile strength followed by welding current and arc voltage. Arc voltage has greatest effect on hardness followed by root gap and welding current. Microstructure of weld metal consists of fine grains of ferrite and pearlite. Keywords: GMAW, MIG, Microstructure, Mild Steel, Welding, Taguchi, ANOVA -----------------------------------------------------------------------***---------------------------------------------------------------------- 1. INTRODUCTION Metal Inert Gas Welding which is also known as Gas Metal Arc Welding (GMAW) uses a consumable metal electrode and an inert gas or an active gas. It is the process in which source of heat is an arc formed between a consumable metal electrode and the work piece. The arc and molten puddle are protected from contamination by the atmosphere with an externally supplied gaseous shield of inert gas or active gas. In this process carbon is used as shielding gas and plate of 12 mm is welded using MIG welding. Hardness testing of metals, ceramics, and composite is useful for a variety of applications for which hardness measurements are unsuitable. Hardness testing gives an allowable range of loads for testing with diamond indenter. The resulting indentation is measured and converted to a hardness value. Taguchi method is a systematic application of design and analysis of experiment for designing purpose and product quality improvements. In this research work tensile strength, hardness and microstructure of specimen 1018 mild steel welded by MIG welding are evaluated. In this paper Taguchi method is used to determine the optimum welding parameter. Taguchi method becomes a powerful tool for improving the productivity in recent year in order to produce high quality products quickly with low cost. A consumable electrode of mild steel with 2mm diameter shielded by carbon dioxide (CO2) gas is used to produce an electric arc with the base metal as shown in Fig. 1. The heat generated by electric arc is used to melt the filler electrode and base metal. As discussed earlier, Taguchi Approach is applied in this process for the analysis. It helps to determine the best level of parameter used to analyze the best performance of the result. Fig-1: MIG welding of Mild Steel 2. LITERATURE REVIEW Suresh Kumar (2002), discuss micro structural development during MIG welding of copper with iron filler. During the experimental work they consider voltage, current and travel speed as welding parameter. They investigate needle shaped morphology of iron matrix typical of martensite and at copper iron interface bended microstructure was observed which varied with travel speed. Haragopal (2011), investigate the mechanical properties of Al-65032 alloy using Taguchi technique and result shows that current is the most influencing parameter for ultimate tensile strength and pressure is most significant parameter for proof stress.