Effect of grain orientation on the corrosion resistance of FSSW joints made in AZ31B

ABSTRACT

Localised corrosion at the weld periphery of AZ31B friction stir spot welds has been associated with microstructural evolution during the welding process. Several attempts have been made to correlate these changes to the corrosion resistance of a joint; however, the influence of grain reorientation arising from the welding process has been overlooked. Here, the role of grain reorientation during FSSW was investigated using a combination of microcapillary polarisation and analytical microscopy. The influence of changes in grain orientation was shown to have a direct effect on the magnitude of the galvanic couple formed between the stir zone and the base metal.

GRAPHICAL ABSTRACT

KEYWORDS:

• Magnesium
• friction stir spot welding
• grain orientation
• EBSD
• microcapillary polarisation

Disclosure statement

No potential conflict of interest was reported by the authors.

Acknowledgment

The authors acknowledge the help of Chris Butcher with EBSD data collection.

ORCID

Yuri Savguira http://orcid.org/0000-0003-1624-3771

Steven J. Thorpe http://orcid.org/0000-0001-8263-2498

Additional information

Funding

The authors acknowledge the financial support from the Natural Science and Engineering Research Council of Canada (NSERC). The EM research described in this paper was performed at the Canadian Centre for Electron Microscopy at McMaster University, which is supported by NSERC and other government agencies.