Research on AZ80 + 0.4%Ce (wt %) Ultra-Thin-Walled Tubes of Magnesium Alloys: The Forming Process, Microstructure Evolution and Mechanical Properties
Abstract
:1. Introduction
2. Materials and Methods
2.1. Strengthening Mechanism
2.2. Materials and Molds
2.3. Experimental Procedures
3. Results and Discussion
3.1. Microstructure Evolution
3.1.1. Φ10 mm × 10 mm Original Extruded Bar
3.1.2. Microstructure Evolution at the Same Temperature with Different Passes
3.1.3. Microstructure Evolution at the Same Pass with Different Temperatures
3.2. Mechanical Properties
4. Conclusions
- (1)
- The molds were designed and thin-walled tubes of AZ80 + 0.4%Ce magnesium alloy with an inside diameter of 6.0 mm and a wall thickness of 0.6 mm were fabricated by hot multi-pass variable wall thickness back extrusion, which can be split into two processes: hot backward extrusion and four-pass hot extension with variable diameters. The success of AZ80 + 0.4%Ce can provide a reference for other magnesium alloys to fabricate ultra-thin walled tubes for electronic components and medical devices.
- (2)
- According to the microstructure analysis, the grain size decreased from 46.3 μm to 8.9 μm with four-pass extension at a deformation temperature of 350 °C and a punch speed of 0.1 mm/s, while there was excessive grain growth at 390 °C and non-uniformity of grain sizes and phases at 310 °C.
- (3)
- Twinning occurred when the deformation temperature was below 310 °C, and disappeared gradually with the increase in accumulated strain. Twinning, precipitation of second phases, twinning dynamic recrystallization (TDRX), and work hardening were combined to change the hardness of tubes at 240 °C and 270 °C. The formation of twins hindered the slip of dislocations and refined grains at the same time. When the temperature reaches 350 °C and higher, the competitive mechanism between work hardening and DRX softening dominates plastic deformation. The hardness reached 93HV after the third extension without annealing at 350 °C and would be higher after heat treatment.
5. Patents
Author Contributions
Funding
Conflicts of Interest
References
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Al | Zn | Ce | Mn | Si | Cu | Fe | Ni | Mg |
---|---|---|---|---|---|---|---|---|
8.90 | 0.53 | 0.40 | 0.20 | ≦0.01 | ≦0.01 | ≦0.005 | ≦0.005 | balance |
Pass | Inner Diameter/mm | Outer Diameter/mm | Wall Thickness Reduction/mm | Cumulative Area Reduction Percentage/% |
---|---|---|---|---|
0 | 6.0 | 10.0 | ||
1 | 6.0 | 9.0 | 0.5 | 43.8 |
2 | 6.0 | 8.4 | 0.3 | 64.0 |
3 | 6.0 | 7.8 | 0.3 | 79.8 |
4 | 6.0 | 7.2 | 0.3 | 91.0 |
Points | Mg | Al | Mn | Ce |
---|---|---|---|---|
f | 8.34 | 45.34 | 36.44 | 9.88 |
g | 47.97 | 40.94 | 9.35 | 0.15 |
h | 55.24 | 34.99 | 9.69 | 0.08 |
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Share and Cite
Yan, Z.; Fang, M.; Lian, Z.; Zhang, Z.; Zhu, J.; Zhang, G.; Wang, Y. Research on AZ80 + 0.4%Ce (wt %) Ultra-Thin-Walled Tubes of Magnesium Alloys: The Forming Process, Microstructure Evolution and Mechanical Properties. Metals 2019, 9, 563. https://doi.org/10.3390/met9050563
Yan Z, Fang M, Lian Z, Zhang Z, Zhu J, Zhang G, Wang Y. Research on AZ80 + 0.4%Ce (wt %) Ultra-Thin-Walled Tubes of Magnesium Alloys: The Forming Process, Microstructure Evolution and Mechanical Properties. Metals. 2019; 9(5):563. https://doi.org/10.3390/met9050563
Chicago/Turabian StyleYan, Zhaoming, Min Fang, Zhendong Lian, Zhimin Zhang, Jiaxuan Zhu, Guanshi Zhang, and Yiding Wang. 2019. "Research on AZ80 + 0.4%Ce (wt %) Ultra-Thin-Walled Tubes of Magnesium Alloys: The Forming Process, Microstructure Evolution and Mechanical Properties" Metals 9, no. 5: 563. https://doi.org/10.3390/met9050563