Influence of pH value, chloride ion concentration and immersion time on corrosion rate of friction stir welded AZ61A magnesium alloy weldments

Magnesium alloys have gained considerable interest as a structural material for automotive and aerospace applications due to its low-density, high specific strength and good castability. As a consequence, this light alloys have a promising future. The limitation of low corrosion resistance restricts their practical applications. The corrosion behavior of friction stir welded AZ61A magnesium alloy welds was investigated by Immersion technique. Extruded Mg alloy plates of 6 mm thick of AZ61A grade were butt welded using friction stir welding (FSW) process. The present paper reveals the effect of pH, chloride ion concentration and immersion time on corrosion rate of friction stir welded AZ61A magnesium alloy welds in NaCl solution. The corrosion rate was evaluated from weight loss measurements. Furthermore, an attempt was made to develop an empirical relationship to predict the effect of pH value, chloride ion concentration and immersion time on corrosion rate of AZ61A magnesium alloy welds. The corrosion morphology observation was carried out by optical microscopy and the corrosion products were analyzed by SEM and XRD analysis. (C) 2012 Elsevier B. V. All rights reserved.