Microstructure and Mechanical Properties of the As-Cast and As-Homogenized Mg-Zn-Sn-Mn-Ca Alloy Fabricated by Semicontinuous Casting
Abstract
:1. Introduction
2. Experimental Procedures
2.1. Semicontinuous Casting
2.2. Homogenization Treatment Process
2.3. Microstructure and Mechanical Properties
3. Results and Discussion
3.1. As-Cast Alloy
3.1.1. Microstructure and Texture
3.1.2. Mechanical Properties and Fracture Behaviors
3.2. As-Homogenized Alloy
3.2.1. Microstructure
3.2.2. Mechanical Properties and Fracture Behaviors
4. Conclusions
- (1)
- The average grain size and the second phase size decrease, but the area fraction of the second phase increases gradually from the center to the surface of the ingot.
- (2)
- The mechanical properties of the alloy in axial direction are slightly better than those in the radial direction, but independent on texture.
- (3)
- The sample at 1/2 radius of the ingot along the axial direction exhibits the optimum comprehensive mechanical properties due to the combined effect of relatively small grain size, low second phase fraction, and uniform microstructure.
- (4)
- In one-step homogenization, the morphology of CaMgSn and grain size has no obvious change when homogenized at 460 °C. While at 500 °C and 540 °C, the CaMgSn is dissolved gradually from long strip-like into short rod-like or chain-like with the increase of homogenization time, and the grains grow obviously when the homogenization time exceeds 16 h.
- (5)
- In two-step homogenization, the low-melting-point phase MgZn2 can be dissolved into the matrix for 10 h at low-temperature stage of 340 °C. At high-temperature stage of 520 °C, with the increase of homogenization time, the elongation of the alloy firstly increases and then decreases, while the yield strength always decreases.
- (6)
- The optimum homogenization process of ZTMX3100 alloy is 340 °C × 10 h + 520 °C × 16 h. After the optimum homogenization treatment, the proper size and morphology of CaMgSn phase are conducive to improve the microstructure uniformity and the mechanical properties of the alloy. Besides, the yield strength of the alloy is reduced by 20.7% and the elongation is increased by 56.3%.
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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Analyzed Element | Actual Composition (wt %) | |||
---|---|---|---|---|
Center | 1/2 Radius | Near the Surface | Average | |
Zn | 3.32 | 3.37 | 3.39 | 3.36 |
Sn | 1.06 | 1.05 | 1.08 | 1.06 |
Mn | 0.32 | 0.34 | 0.34 | 0.33 |
Ca | 0.26 | 0.27 | 0.28 | 0.27 |
Mg | Bal. | Bal. | Bal. | Bal. |
Point | Mg | Zn | Sn | Ca | ||||
---|---|---|---|---|---|---|---|---|
wt % | at % | wt % | at % | wt % | at % | wt % | at % | |
D | 64.35 | 85.76 | 2.99 | 1.48 | 25.47 | 6.95 | 7.18 | 5.81 |
E | 76.94 | 91.45 | 4.05 | 1.79 | 14.56 | 3.54 | 4.46 | 3.21 |
F | 43.94 | 67.82 | 56.06 | 32.18 | - | - | - | - |
G | 99.13 | 99.68 | 0.87 | 0.32 | - | - | - | - |
Areas | YS (MPa) | UTS (MPa) | EL (%) |
---|---|---|---|
Along the radial direction | |||
Center | 81.3 ± 2.0 | 210.0 ± 2.0 | 14.0 ± 0.4 |
1/2 radius | 82.0 ± 1.1 | 207.0 ± 0.9 | 15.0 ± 0.7 |
Near the surface | 75.0 ± 0.9 | 199.0 ± 1.3 | 13.5 ± 1.1 |
Along the axial direction | |||
Center | 82.5 ± 0.5 | 212.0 ± 2.4 | 14.9 ± 0.9 |
1/2 radius | 84.5 ± 1.2 | 210.0 ± 0.9 | 16.0 ± 0.8 |
Near the surface | 76.0 ± 1.1 | 202.0 ± 1.5 | 14.2 ± 0.7 |
Homogenization Conditions | YS (MPa) | UTS (MPa) | EL (%) |
---|---|---|---|
One-step homogenization | |||
460 °C × 16 h | 78.0 ± 2.5 | 225.0 ± 0.5 | 17.0 ± 0.4 |
500 °C × 16 h | 72.0 ± 0.8 | 223.0 ± 1.6 | 17.5 ± 0.8 |
540 °C × 16 h | 71.0 ± 0.5 | 230.0 ± 1.0 | 20.0 ± 0.5 |
Two-step homogenization | |||
340 °C × 10 h + 560 °C × 4 h | 69.0 ± 2.8 | 225.0 ± 0.7 | 21.5 ± 0.4 |
340 °C × 10 h + 560 °C × 8 h | 67.0 ± 0.5 | 226.0 ± 1.2 | 21.0 ± 1.3 |
340 °C × 10 h + 560 °C × 16 h | 68.0 ± 0.7 | 224.0 ± 0.8 | 16.3 ± 1.1 |
340 °C × 10 h + 560 °C × 24 h | 32.0 ± 4.2 | 125.0 ± 3.8 | 15.3 ± 2.1 |
340 °C × 10 h + 520 °C × 4 h | 72.0 ± 1.2 | 226.0 ± 0.9 | 18.5 ± 0.7 |
340 °C × 10 h + 520 °C × 8 h | 70.0 ± 0.9 | 223.0 ± 1.5 | 20.5 ± 0.7 |
340 °C × 10 h + 520 °C × 16 h | 67.0 ± 0.7 | 228.0 ± 0.7 | 25.0 ± 0.5 |
340 °C × 10 h + 520 °C × 24 h | 66.0 ± 1.1 | 225.0 ± 1.4 | 22.5 ± 0.9 |
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Lu, X.; Zhao, G.; Zhou, J.; Zhang, C.; Yu, J. Microstructure and Mechanical Properties of the As-Cast and As-Homogenized Mg-Zn-Sn-Mn-Ca Alloy Fabricated by Semicontinuous Casting. Materials 2018, 11, 703. https://doi.org/10.3390/ma11050703
Lu X, Zhao G, Zhou J, Zhang C, Yu J. Microstructure and Mechanical Properties of the As-Cast and As-Homogenized Mg-Zn-Sn-Mn-Ca Alloy Fabricated by Semicontinuous Casting. Materials. 2018; 11(5):703. https://doi.org/10.3390/ma11050703
Chicago/Turabian StyleLu, Xing, Guoqun Zhao, Jixue Zhou, Cunsheng Zhang, and Junquan Yu. 2018. "Microstructure and Mechanical Properties of the As-Cast and As-Homogenized Mg-Zn-Sn-Mn-Ca Alloy Fabricated by Semicontinuous Casting" Materials 11, no. 5: 703. https://doi.org/10.3390/ma11050703
APA StyleLu, X., Zhao, G., Zhou, J., Zhang, C., & Yu, J. (2018). Microstructure and Mechanical Properties of the As-Cast and As-Homogenized Mg-Zn-Sn-Mn-Ca Alloy Fabricated by Semicontinuous Casting. Materials, 11(5), 703. https://doi.org/10.3390/ma11050703