Title: Studies on the corrosion characteristics of friction stir welded AZ61A magnesium alloy welds under immersion tests and potentiodynamic polarisation tests: a comparative evaluation

Authors: A. Dhanapal; S. Rajendra Boopathy; V. Balasubramanian; K. Chidambaram; A.R. Thoheer Zaman

Addresses: Department of Mechanical Engineering, Sri Ramanujar Engineering College, Chennai – 600 048, Tamil Nadu, India ' Department of Mechanical Engineering, College of Engineering, Guindy, Anna University, Chennai – 600 025, Tamil Nadu, India ' Department of Manufacturing Engineering, Center for Materials Joining and Research (CEMAJOR), Annamalai University, Annamalainagar, Chidambaram – 608 002, Tamil Nadu, India ' Sri Ramanujar Engineering College, Vandalur, Chennai – 600 048, Tamil Nadu, India ' Department of Mechanical Engineering, Sri Ramanujar Engineering College, Vandalur, Chennai – 600 048, Tamil Nadu, India

Abstract: Extruded Mg alloy plates of 6 mm thick of AZ61A grade were butt welded using friction stir welding (FSW) process. The experimental techniques used in this investigation include immersion studies and potentiodynamic polarisation tests. The specimens were exposed to immersion and polarisation environments in order to evaluate their corrosion rates. Additionally, an attempt was made to develop an empirical relationship to predict the corrosion rate of the FSW joints in immersion tests and polarisation tests using response surface methodology. The developed relationship can be effectively used to predict the corrosion rate of friction stir welded AZ61A magnesium alloy at 95% confidence level for both the test conditions. This research work proves a better corrosion resistance of AZ61A magnesium alloy welds at the alkaline solution than the acidic and the neutral solutions, moreover, low corrosion rate was found at low concentrated solution and higher exposure time respectively.

Keywords: magnesium alloys; friction stir welding; FSW; response surface methodology; RSM; partially protective surface film; pit morphology; corrosion rates; magnesium alloy welds; immersion tests; potentiodynamic polarisation tests; butt welding.

DOI: 10.1504/IJCMSSE.2013.056951

International Journal of Computational Materials Science and Surface Engineering, 2013 Vol.5 No.3, pp.262 - 287

Received: 09 Nov 2012
Accepted: 24 Apr 2013

Published online: 21 Jun 2014 *

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