The effects of aging treatment on the high temperature mechanical behavior of laser-welded Mg-Gd-Y alloy were systematically studied. The microstructure and high temperature tensile properties of as-welded and aging-treated joints were analyzed. The microhardness of the weakest part of the heat affected zone was improved by 41% due to the precipitation of large amount of β′ and the ultimate tensile strengths at room temperature and 300 °C was increased by 11 and 8% by aging treatment. The elevated temperature tensile properties of two types of joints decreased slightly from room temperature to 250 °C, then plummeted at 300 °C. The failure mechanism of aging-treated joints was the originating and propagation of cracks at the interior of Mg24(Gd,Y)5 by the local stress concentration when the temperature was lower than 250 °C, whereas the failure mechanism at 300 °C was the deformation of ultrafine grains and unstable Mg24(Gd,Y)5.
Journal of Materials Engineering and Performance – Springer Journals
Published: May 11, 2021