Effect of Heat Input on Porosity Defects in a Fiber Laser Welded Socket-Joint Made of Powder Metallurgy Molybdenum Alloy
Abstract
:1. Introduction
2. Materials and Methods
3. Results and Discussion
3.1. Morphologies of Welded Joints
3.2. Porosity Defects
3.3. Analysis on Porosity Formation
3.3.1. Inherent Characteristic of Powder Metallurgy Materials
3.3.2. Overflowing of Bubbles in the Molten Pool
3.3.3. Formation of Pores with Double Curvature Contour
4. Conclusions
- (1)
- Laser welding of an NS-Mo alloy under a low heat input resulted in less spatters, and a smooth weld surface. In contrast, a large amount of spatter was observed for samples prepared with a high heat input.
- (2)
- When the welding heat input decreased from 3600 J/cm to 250 J/cm, the porosity ratio of the NS-Mo joints declined from 10.7% to 2.1%.
- (3)
- Notable irregularly-shaped porosities formed under a high welding heat input were mainly related to the instability of the keyhole, while the spherical defects formed at a low welding heat input were due to the fact that bubbles released from the powder metallurgy BM did not have enough time to escape.
Author Contributions
Funding
Conflicts of Interest
References
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Sample Number | Heat Input (J/cm) | Laser Power (W) | Welding Speed (m/min) | Defocusing Distance (mm) |
---|---|---|---|---|
Joint 1 | 250 | 2500 | 6 | 1 |
Joint 2 | 3600 | 1200 | 0.2 | 1 |
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Xie, M.-X.; Li, Y.-X.; Shang, X.-T.; Wang, X.-W.; Pei, J.-Y. Effect of Heat Input on Porosity Defects in a Fiber Laser Welded Socket-Joint Made of Powder Metallurgy Molybdenum Alloy. Materials 2019, 12, 1433. https://doi.org/10.3390/ma12091433
Xie M-X, Li Y-X, Shang X-T, Wang X-W, Pei J-Y. Effect of Heat Input on Porosity Defects in a Fiber Laser Welded Socket-Joint Made of Powder Metallurgy Molybdenum Alloy. Materials. 2019; 12(9):1433. https://doi.org/10.3390/ma12091433
Chicago/Turabian StyleXie, Miao-Xia, Yan-Xin Li, Xiang-Tao Shang, Xue-Wu Wang, and Jun-Yu Pei. 2019. "Effect of Heat Input on Porosity Defects in a Fiber Laser Welded Socket-Joint Made of Powder Metallurgy Molybdenum Alloy" Materials 12, no. 9: 1433. https://doi.org/10.3390/ma12091433