Regularities of porosity formation in electron beam welding of aluminium alloys under lower gravity
Heading:
| 1Lobanov, LM, 1Milenin, OS, 1Ternovyi, Ye.G, 1Piskun, NV, 1Hlushak, SO, 1Statkevich, II, 1Radchenko, LM 1E.O. Paton Electric Welding Institute of the National Academy of Sciences of Ukraine, Kyiv, Ukraine |
| Space Sci. & Technol. 2023, 29 ;(3):57-66 |
| https://doi.org/10.15407/knit2023.03.057 |
| Publication Language: Ukrainian |
Abstract: The use of welding processes in open space is necessary for the manufacture, assembly, and repair of large-sized structures of space stations both in the near-Earth orbit and during the exploration of the Moon, where it is planned the creation of long-term lunar bases (LLB), as well as other objects that ensure the activities and work of expeditions. These can be subassembly operations in creating pressure-tight buildings for residential and industrial use, as well as for storing energy resources, pipelines of space complexes, or repair for ensuring the long-term operation of existing systems.
Electron beam welding (EBW) is an optimal and more technological process for these works in comparison with other welding methods. Deep vacuum and low temperatures, which are the natural environment under space conditions, encourage the use of electron beam technologies, including welding. The efficiency of this process is 85¾90 %, which is the maximum one in comparison with other welding methods. EBW under Earth gravity allows gaining the mechanical and chemical properties, as well as vacuum tightness of welded joints at the level of the parent metal.
Performing EBW in conditions of ultrahigh vacuum, low gravity, and low temperatures is complicated, therefore, the quality of welded joints may decrease. The obtained results of the experiments conducted under conditions of low gravity and low temperatures in space, as well as in the flying laboratory, showed an increased number of pores in the welds. First of all, this phenomenon was detected in the welding of samples made of aluminum alloys. They are widely used in creating space structures, which does not exclude the possibility of their application in the manufacture of welded structures on the Moon’s surface.
The aim of this work is the studying the regularities of porosity formation in the metal of the welded joints made of aluminum alloys in EBW under low gravity by qualitative analysis of the main factors that determine the increased susceptibility to the formation of discontinuities of this type.
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| Keywords: ablation pressure, aluminum alloys, balance of forces, collapse, discontinuities, electron beam welding, experimental results, gas bubble trajectory, gas bubbles, hydrodynamics, hydrostatic balance, keyhole, porosity formation, reduced gravity, Reynolds numbers, ultra-high vacuum, welded joints |
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https://doi.org/10.1007/978-3-030-21894-2_59
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https://doi.org/10.15407/knit2017.04.027
2. Bondarev A. A. (1972). The influence of technological factors on the properties and density of welds of aluminum alloys made by electron beam welding. Automatic welding, № 5, 24¾26 [in Ukrainian].
3. Bondarev A. A., Lapchynskyj V. F., Lozovskaia A. V., Ternovoj E. H. (2000). Investigation of the structure and distribution of elements in welded joints made by an electron beam on 1201 and AMg6 alloys under weightless conditions. Space: Technology, Materials Science, Constructions. Collection of scientific papers under. edited by Academician B. E. Paton. Kyiv: PWI them. E.O. Paton NAS of Ukraine, 247¾252 [in Russian].
4. Bondarev A.A. Rabkin D.M. Evaporation of volatile elements during electron beam welding of aluminum alloys. Automatic welding. 1974. No. 3. 13-16 [in Russian].
5. Paton B. E., Lapchinsky V. F. (1998). Welding and related technologies in space. Peculiarities and Prospects. Kyiv. Naukova dumka. 182 P. [in Russian].
6. Paton B. E., Kubasov V. N. (1970). Eksperyment po svarke metallov v kosmose[Tekst]. Experiment on welding metals in space. Automatic welding, № 5, 7¾12 [in Russian].
7. Rabkyn D. M., Lapchynskyj V. F., Ternovoj E. H., Lozovskaia A.V., Mnyshenko S.V., Bondarev A.A., Dzykovych Y. Ya. (2000). Investigation of the properties and structure of welded joints from alloy 1201, made by an electron beam at various levels of gravity and low temperatures. Space: Technology, Materials Science, Constructions. Collection of scientific papers under. edited by Academician B. E. Paton. Kyiv: PWI them. E.O. Paton National Academy of Sciences of Ukraine, 236¾243 [in Russian].
8 Ternovoj E. H., Bondarev A. A., Lapchynskyj V .F., Havrysh S. S., Afanas'ev Y. V., Fylymonov V .Y. (1976). Investigation of some issues of weldability of aluminum alloys in weightlessness. Space research in Ukraine, № 9, 5¾11 [in Russian].
9. Ternovoj E. H., Bondarev A. A., Lapchynskyj V. F, Lozovskaia A. V. (2000). Influence of gravitational forces, dissolved hydrogen and initial temperature on the properties and density of welded joints in electron-beam welding of light structural alloys. Space: Technology, Materials Science, Constructions. Collection of scientific papers under. edited by Academician B.E. Paton. Kyiv: PWI them. E. O. Paton NAS of Ukraine, 243¾246 [in Russian].
10. Ternovyi Y. G., Lobanov L. М. (2019). Features of electron-beam welding of thick-walled shells made of aluminium alloys. 7 - the International conference "Space technologies: present and future". Abstracts reports. Dnipro. 93 [in Russian].
11. Ternovyi Y. G., Paton B. E., Lobanov L. М., Asnis Y. А., Zubchenko Yu. V., Statkevych І. І. Complex of equipment for electron-beam welding in Moon surface conditions. (2019). 7 - the International conference "Space technologies: present and future". Abstracts reports. Dnipro, 113 [in Ukrainian].
12. Alexopoulou V.E., Papazoglou E.L., Karmiris-Obratański P., Markopoulos A.P. (2022). 3D finite element modeling of selective laser melting for conduction, transition and keyhole modes. Journal of Manufacturing Processes, Vol. 75, P. 877-894.
https://doi.org/10.1016/j.jmapro.2022.01.054
13. Blackburn J. E. (2011). Understanding porosity formation and prevention when welding titanium alloys with 1 μm wavelength laser beams. A thesis for the degree of Doctor of Engineering. Faculty of Engineering and Physical Sciences. School of Mechanical, Aerospace and Civil Engineering. The University of Manchester.
14. Clift R., Grace J. R., Weber M. E. (2013). Bubbles, drops and particles. New York. Dover Publication Inc. 400 p.
15. Duley W. W. (1999). Heat transfer and modelling in laser welding. Laser Welding. New York: Wiley & Sons. 264 p.
16. Forsman T. (2000). Laser Welding of Aluminium Alloys. Doctoral Thesis. Department of Materials and Manufacturing Engineering Division of Manufacturing Systems Engineering. Lulea University of Technology.
17. Iida T., Guthrie R. I. L. (1993). The Physical Properties of Liquid Metals. Oxford: Clarendon Press, 288 p.
18. Jingsheng W., Renzhi H., Xin C., Shengyong P. (2018). Modeling fluid dynamics of vapor plume in transient keyhole during vacuum electron beam welding. Vacuum, 15, Vol. 157, P. 277-290.
https://doi.org/10.1016/j.vacuum.2018.08.059
19. Klein T., Vicanek M., Kroos J., Decker I., Simon G. (1994). Oscillations of the keyhole in penetration laser beam welding. J. Phys. D: Appt. Phys, 27, 2023¾2030.
https://doi.org/10.1088/0022-3727/27/10/006
20. Kroos J., Gratzke U., Simon G. (1993). Towards a self-consistent model of the keyhole in penetration laser beam welding. J. Phys. D: Appl. Phys., 26, 474¾480.
https://doi.org/10.1088/0022-3727/26/3/021
21. Milenin A., Velikoivanenko E., Rozynka G., Pivtorak N. (2019). Residual Strength and Reliability of Corroded Pipelines-Monte-Carlo Approach for Consideration of Spatially Nonuniform Material Properties. Structural Integrity, 8, 321¾326.
https://doi.org/10.1007/978-3-030-21894-2_59
22. Paton, B.E., Lobanov, L.M., Asnis, Yu.A., Ternovoj, E.G., Zubchenko, Yu.V. (2017). Equipment and technology for electron-beam welding in space. Space Materials and Technologies. 23(4). 27-32
https://doi.org/10.15407/knit2017.04.027