Susceptibility of magnesium alloys to solidification cracking

Abstract

Solidification cracking of Mg welds has been reported frequently, but the crack susceptibility itself has not been studied much. In the present investigation the widely used Mg alloys AZ31, AZ61, AZ91 and ZK61 were selected for the study. The crack susceptibility was predicted based on the maximum │dT/d(f_S)^1/2│ up to (f_S)^1/2 = 0.99 as the crack susceptibility index (T: temperature; f_S: fraction of solid). The predicted crack susceptibility decreased in the order of ZK61 > AZ31 > AZ61 > AZ91. Since no reported data were available for comparison with the prediction, the transverse motion weldability (TMW) test was conducted. The tested crack susceptibility decreased in the order of ZK61 > AZ31 > AZ61 > AZ91, thus verifying the prediction based on the index │dT/d(f_S)^1/2│. The present study demonstrated that the crack susceptibility index and the TMW test can be useful tools for studying solidification cracking of Mg welds.

KEYWORDS:

• Solidification cracking
• Mg alloys
• TMW test
• welding ZK61
• AZ31
• AZ61
• AZ91

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Kun Liu http://orcid.org/0000-0002-9960-4810

Additional information

Funding

This work was supported by the National Science Foundation initially under grant number DMR 1500367 and subsequently under grant number DMR1904503. Kun Liu was supported by the China Scholarship Council [grant number 201706220201] as a visiting graduate student at the University of Wisconsin–Madison.