International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 3, Number 1, January - June (2012), © IAEME 48 STUDIES ON THE EFFECTS OF OXIDATION AND ITS REPRESSION IN MAG WELDING PROCESS A. Chennakesava Reddy Department of Mechanical Engineering JNTUH College of Engineering and Technology Hyderabad - 500085 Andhra Pradesh, India e-mail: dr_acreddy#yahoo.com ABSTRACT This article highlights repression of oxidation tendency of CO 2 in MAG welding. The results conclude that deoxidizers (Mn, Si and Al) used in the electrodes have suppressed the oxidation of alloying elements in both the electrode and base metal. The resistance to hot cracking has been improved due to the reduction of S and P. Keywords: MAG welding, oxidation, repression INTRODUCTION Metal active gas (MAG) welding is a variation of the standard metal inert gas (MIG) welding process. In MAG welding process the active gas is carbon dioxide (CO 2 ) which acts as a shielding gas. MAG welding overcomes the restriction of using small lengths of electrodes as in manual metal - arc welding and sub dues the inability of the submerged are welding process to weld in various positions [1]. The effects of shielding of CO 2 to carbon and low alloy steels have been examined by several investigators. Under welding conditions, CO 2 decomposes into carbon monoxide and oxygen and becomes oxidising in the arc. The molecular oxygen further changes to atomic form in the weld zone. The atomic oxygen being very active may react with the base metal and other alloying elements as well as with the elements of electrode. Such reactions in the weld bead produce oxides and pin/blow holes that subsequently affect the mechanical properties of weld joints. According to Jilong and Apps, the use of CO 2 shielding produces an aggressive and violent arc [2]. Reddy et al [3] have concluded that the effect CO 2 shielding was equivalent to that of a gas mixture of 90 % argon and 10 % oxygen. INTERNATIONAL JOURNAL OF ADVANCED RESEARCH IN ENGINEERING AND TECHNOLOGY (IJARET) ISSN 0976 - 6480 (Print) ISSN 0976 - 6499 (Online) Volume 3, Issue 1, January- June (2012), pp. 48-54 © IAEME: www.iaeme.com/ijaret.html Journal Impact Factor (2011): 0.7315 (Calculated by GISI) www.jifactor.com \ IJARET © I A E M E