Notch Tensile Behavior of the Mg-Zn-Gd-Zr Alloy
- Ramaiah Institute of Technology (India)
- CEMILAC, Defence R&D Organization (India)
The Mg-Zn-Gd-Zr alloy is one of the important aerospace alloys in the aircraft gearbox applications. The complex geometry of the gearbox introduces several stress concentration points with various intensities. These regions are susceptible to catastrophic failure under mixed loading condition. Therefore, it is important to understand the deformation and failure mode of this alloy for various plastic constraint conditions. In the present work, Mg-4%Zn-1.5%Gd-0.5%Zr alloys were prepared with four different increasing notch root radii (1, 2, 4 and 8 mm). These samples were tested for tensile properties and compared with the smooth condition. In addition, notch sensitivity was determined analytically. The microstructure and fracture samples of the alloy were characterized with the aid of an optical/scanning electron microscope. Tensile test results show that the alloy is notch sensitive and shows notch-strengthening effects. The notch strength ratio increases with the decrease in the notch root radius due to the strong plastic constraint. The predicted and experimental results of the fracture strain with the notch root radius are in qualitative agreement. The void growth rate prediction is qualitatively in agreement with the tensile and fractography results and suggests that the notch geometry has a significant influence on the plastic strain of the alloy. The microstructure of the alloy has equiaxed grains of 74 ± 24 µm with the grain boundary eutectic. The eutectic is composed of Gd-rich Mg phase. The fracture surface has a distinct change from mixed mode to complete cleavage with the increasing notch root radius. The fractography results show that the fracture mode is predominantly intergranular for all the cases.
- OSTI ID:
- 22970747
- Journal Information:
- Journal of Materials Engineering and Performance, Vol. 28, Issue 6; Conference: Draf 2018: International Symposium on Dynamic Response and Failure of Composite Materials, Naples (Italy), 12-15 Jun 2018; Other Information: Copyright (c) 2019 ASM International; Country of input: International Atomic Energy Agency (IAEA); ISSN 1059-9495
- Country of Publication:
- United States
- Language:
- English
Similar Records
Notch fracture in {gamma}-titanium aluminides
In-situ SEM observations of crack nucleation and propagation in a notched tensile specimen of Ni{sub 3}Al with boron