Effect of intermetallics on susceptibility of Mg alloy welds to liquation cracking

ABSTRACT

The circular-patch welding test was used to study the liquation and liquation cracking of AZ-series Mg alloys. A heat treatment was carried out on the as-received AZ91 alloy to dissolve the γ(Mg₁₇Al₁₂) particles before welding. The circular-patch welding test was then conducted on the heat-treated, as-received AZ91 alloy using AZ61 and AZ91 filler wires. The results showed that the susceptibility of AZ91 alloy to liquation and liquation cracking was significantly reduced by the dissolution of massive γ(Mg₁₇Al₁₂) particles via a heat treatment before welding as the liquation mechanism was changed. Both constitutional liquation and incipient melting occurred in the partially melted zone of the as-received AZ91 welds, while only incipient melting occurred in the heat-treated AZ91 welds.

KEYWORDS:

• Magnesium alloys
• intermetallic compounds
• liquation cracking
• heat treatment

Acknowledgements

The authors appreciate the suggestions from Professor Sindo Kou, University of Wisconsin–Madison, USA. This work was supported by the Natural Science Foundation of China (grant number 51704013) and the Beijing Municipal Education Commission Fund (grant number KM201810005016). We thank Sara Maccagnano-Zacher, PhD, from Edanz Group, for editing the English text of this manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Natural Science Foundation of China [grant number 51704013]; the Beijing Municipal Education Commission [grant number KM201810005016].