%0 Journal Article
%T Experimental Investigation of the Corrosion Behavior of Friction Stir Welded AZ61A Magnesium Alloy Welds under Salt Spray Corrosion Test and Galvanic Corrosion Test Using Response Surface Methodology
%A A. Dhanapal
%A S. Rajendra Boopathy
%A V. Balasubramanian
%A K. Chidambaram
%A A. R. Thoheer Zaman
%J International Journal of Metals
%D 2013
%R 10.1155/2013/317143
%X Extruded Mg alloy plates of 6£żmm thick of AZ61A grade were butt welded using advanced welding process and friction stir welding (FSW) processes. The specimens were exposed to salt spray conditions and immersion conditions to characterize their corrosion rates on the effect of pH value, chloride ion concentration, and corrosion time. In addition, an attempt was made to develop an empirical relationship to predict the corrosion rate of FSW welds in salt spray corrosion test and galvanic corrosion test using design of experiments. The corrosion morphology and the pit morphology were analyzed by optical microscopy, and the corrosion products were examined using scanning electron microscope and X-ray diffraction analysis. From this research work, it is found that, in both corrosion tests, the corrosion rate decreases with the increase in pH value, the decrease in chloride ion concentration, and a higher corrosion time. The results show the usage of the magnesium alloy for best environments and suitable applications from the aforementioned conditions. Also, it is found that AZ61A magnesium alloy welds possess low-corrosion rate and higher-corrosion resistance in the galvanic corrosion test than in the salt spray corrosion test. 1. Introduction Magnesium alloys have received extensive recognition due to their excellent physical properties, including light weight, high strength/weight ratio, high thermal conductivity, and good electromagnetic shielding characteristics; thus, become promising candidates to replace steel and aluminum alloys in many structural and mechanical applications due to their attractive mechanical and metallurgical properties [1, 2]. The joining of magnesium components made from this alloy is, however, still limited. Unfortunately, conventional fusion welding of magnesium alloys often produces porosity and hot cracks in the welded joint. This deteriorates both the mechanical properties and corrosion resistance [3, 4]. Hence, it will be of extreme benefit if a solid state joining process, that is, one which avoids bulk melting of the base materials, hot cracking, and porosity, can be developed and carried out for the joining of magnesium alloys. FSW is a solid state welding process without emission of ration or dangerous fumes, and it avoids the formation of solidification defects like hot cracking and porosity. Moreover, it significantly improved the weld properties and had been extensively applied in the joining of magnesium alloys [5]. The application of Mg alloy in the structural members is still limited due to its conventional fusion
%U http://www.hindawi.com/journals/ijmet/2013/317143/