N. B. Pugacheva and S. M. Zadvorkin

MICROSTRUCTURE, RESIDUAL STRESSES, TEXTURE, AND MECHANICAL PROPERTIES OF A WELDED JOINT IN VT1-0 ALLOY SHEETS

The grain structure, microstrain distribution, crystallographic texture and residual stresses in a CO2 laser welded joint of VT1-0 alloy sheets (technical titanium) are studied by EBSD and X-ray diffraction analysis. The mechanical properties of the welded joint are determined. It is shown that the weld structure is represented by differently directed large laths of the α-phase. The metal in the heat-affected zones is characterized by a mixed structure resulting from the polymorphic β→α transformation in the form of packets of secondary α-phase plates near the weld and polyhedral α-grains near the base metal. Multicomponent textures have been detected in all the zones of the welded joint. This creates prerequisites for decreased anisotropy of strength properties, which is typical of hexagonal crystals. The strength of the welded joint proves to be significantly higher than that of the base metal; namely, the ultimate strength of the joint is 660 MPa, and that of the base material is 500 MPa. The heat-affected zone is the most deformed zone in the welded joint, the share of deformed grains reaches 44%, and residual stresses do not exceed 10% of the yield strength.

Acknowledgment: The research was done under the state assignment for IES UB RAS, theme No. 124020700063-3.

References:

1. Gorynin, I.V. and Chechulin, B.B. Titan v mashinostroenii [Titanium in Manufacturing]. Mashinostroenie Publ., Moscow, 1990, 400 p. (In Russian).
2. Kolachev, B.A., Livanov, V.A., and Bukhanova, A.A. Mekhanicheskie svoystva titana i ego splavov [Mechanical Properties of Titanium and its Alloys]. Metallurgiya Publ., Мoscow, 1974, 544 p. (In Russian).
3. Nikonov, N.V., Chapala, Yu.I., and Gorelik, N.E. Titan. Svoistva, primenenie, proizvodstvo, konechnaya produktsiya i ee primeneniya [Titanium. Properties, Applications, Production, End Products and Their Applications]. Metotekhnika Publ., Moscow, 2019. (In Russian). Available at: https://www. metotech.ru/articles/art_titan_4.pdf
4. Bubnov, V.A. and Knyazev, A.N., Titanium and its alloys in mechanical engineering. Vestnik KGU, 2016, 3, 92–96. (In Russian).
5. Kolachev, B.A., Elagin, V.I., and Livanov, V.A. Metallovedenie i termicheskaya obrabotka tsvetnykh metallov i splavov [Metal Science and Heat Treatment of Non-Ferrous Metals and Alloys]. MISIS Publ., Moscow, 2005, 432 p. (In Russian).
6. Svoystva elementov: spravochnik [Properties of Elements: A Handbook, ed. by G.V. Samsonov. Part 1]. Metallurgiya Publ., Moscow, 1976, 599 p. (In Russian).
7. Zolotorevskii, V.S. Меkhanicheskie svoistva metallov [Mechanical Properties of Metals]. MISIS Publ., Moscow, 1998, 400 p. (In Russian).
8. Shorshorov, M.Kh. Metallovedenie svarki stali i splavov titana [Metal Science of Welding Steel and Titanium Alloys]. Nauka Publ., Moscow, 1965, 336 p. (In Russian).
9. Prokhorov, N.N. Fizicheskie protsessy v metallakh pri svarke: v 2 t. T. 2 [Physical Processes in Metals During Welding. Vol. 2]. Metallurgiya Publ., Moscow, 1976, 600 p. (In Russian).
10. Rykalin, I.I., Uglov, A.A., Zuev, I.V., and Kokora, A.N. Lazernaya i elektronno-luchevaya obrabotka materialov [Laser and Electron-Ray Treatment of Materials: Handbook]. Mashinostroenie Publ., Moscow, 1985, 496 p. (In Russian).
11. Grigoryants, A.G. and Shiganov, I.N. Lazernaya tekhnika i tekhnologiya: v 7 kn. Kn. 5 [Laser Equipment and Technology: in 7 books. Book. 5]. Vysshaya Shkola Publ., Moscow, 1988. 207 p. (In Russian).
12. Orishich, A.M., Cherepanov, A.N., Shapeev, V.P., and Pugacheva, N.B. Nanomodifitsirovanie svarnykh soedinenii pri lazernoi svarke metallov i splavov [Nano-Modification of Welds by Laser Welding Metals and Alloys]. SO RAN Publ., Novosibirsk, 2014, 252 p. (In Russian).
13. Schwarzer, R.A., Field, D.P., Adams, B.L., Kumar, M., and Schwartz, A.J. Present state of electron backscatter diffraction and prospective developments. In: Schwartz, A., Kumar, M., Adams, B., and Field, D., eds. Electron Backscatter Diffraction in Materials Science, Springer, Boston, MA, 2009, ch. 1, pp. 1–20. DOI: 10.1007/978-0-387-88136-2_1
14. Maurice, C. and Fortunier, R. A 3D Hough transform for indexing EBSD and Kossel patterns. Journal of Microscopy, 2008, 230 (3), 520–529. DOI: 10.1111/j.1365-2818.2008.02045.x.
15. Liu, H., Shui, J, Cai, T., Chen, Q., Song, X.G., and Yang, G.J. Microstructural evolution and hardness response in the laser beam welded joints of pure titanium during recrystallization and grain growth. Materials Characterization, 2018, 145, 87–95. DOI: 10.1016/j.matchar.2018.08.036.
16. Liu, H., Nakata, K., Zhang, J.X., Yamamoto, N., and Liao, J., Microstructural evolution of fusion zone in laser beam welds of pure titanium. Materials Characterization, 2012, 65, 1–7. DOI: 10.1016/j.matchar.2011.12.010.
17. Rusakov, A.A. Rentgenografiya metallov [X-ray Diffraction of Metals]. Atomizdat Publ., Moscow, 1977, 480 p. (In Russian).
18. Silnikova, E.F. and Silnikov, M.V. Kristallograficheskaya tekstura i teksturoobrazovanie [Crystallographic Texture and Texture Formation]. Nauka Publ., St. Petersburg, 2011, 60 p. (In Russian).
19. Borodkina, M.M. and Spektr, E.N. Rentgenograficheskii analiz tekstur metallov i splavov [X-Ray Analysis of the Textures of Metals and Alloys]. Metallurgiya Publ., Moscow, 1981, 272 p. (In Russian).
20. Shaskolskaya, M.P. Kristallografiya [Crystallography]. Vysshaya Shkola Publ., Moscow, 1976, 391 p. (In Russian).
21. CRC Handbook of Chemistry and Physics, 90th edition, ed. by D.R. Lide, CRC Press, Boca Raton, FL, 2009–2010, 2804 p.
22. Khorev, A.I. Heat and thermomechanical treatment and textural hardening of weldable titanium alloys. Welding International, 2013, 27 (10), 798–805. DOI: 10.1080/09507116.2013.796630.
23. Wei, H.L., Elmer, J.W., and DebRoy, T. Crystal growth during keyhole mode laser welding. Acta Materialia, 2017, 133, 10–20. DOI: 10.1016/j.actamat.2017.04.074.
24. Zhang, C.J., Guo, C.X., Zhang, S.Z., Feng, H., Chen, C.Y., Zhang, H.Z., and Cao, P. Microstructural manipulation and improved mechanical properties of a near α titanium alloy. Materials Science and Engineering: A, 2020, 771, 138569. DOI: 10.1016/j.msea.2019.138569.
25. Uwanyuze, R.S., Kanyo, J.E., Myrick, S.E., and Schaffӧner, S. A review on alpha case formation and modeling of mass transfer during investment casting of titanium alloys. Journal of Alloys and Compounds, 2021, 865 (5), 158558. DOI: 10.1016/j.jallcom.2020.158558.
26. Jha, J.S., Toppo, S.P., Singh, R, Tewari, A., and Mishra, S.K. Deformation behavior of Ti–6Al–4V microstructures under uniaxial loading: equiaxed vs. transformed-β microstructures. Materials Characterization, 2021, 171, 1107080. DOI: 10.1016/j.matchar.2020.110780.
27. Pugacheva, N.B., Trushina, E.B., and Pugacheva, E.I. Laser welding of Ti–5Al–2.5Sn titanium alloy. Voprosy Materialovedeniya, 2013, 2 (74), 83–92. (In Russian).
28. Pugacheva, N.B., Vichuzhanin, D.I., and Antenorova, N.P. Hardness and character of destruction of welded joints of VT5-1 titanium alloy. Deformatsiya i Razrushenie Materialov, 2014, 3, 33–38. (In Russian).
29. Pugacheva, N.B., Zadvorkin, S.M., and Michurov, N.S. EBSD analysis of laser welded joint of austenitic Cr-Ni steel. Physics of Metals and Metallography, 2022, 123, 791–796. DOI: 10.1134/S0031918X22080087.
30. Chirkin, V.S. Teplofizicheskie svoystva materialov yadernoy tekhniki: spravochnik [Thermophysical Properties of Nuclear Engineering Materials: Handbook]. Atomizdat Publ., Moscow, 1968, 484 p. (In Russian).

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