Metallurgical aspects of joining commercially pure titanium to Ti-6Al-4V alloy in a T-joint configuration by laser beam welding
- 257 Downloads
The present paper focuses on the metallurgical and microstructural characterization of the laser beam-welded T-joints between commercially pure titanium (CP-Ti) and Ti-6Al-4V alloy. The weld regions were comprehensively studied and the mechanisms leading to the final morphology within each weld region were described. The link between microstructural features and local mechanical properties was demonstrated. Owing to different constitution, the responses of the two titanium alloys to thermal cycles imposed by laser welding are completely different. A strong interface with no dilution zone between the two alloys was observed. The cooling rate during the welding process is high enough for diffusionless martensitic transformation in the Ti-6Al-4V part of the fusion zone. In contrast, no evidence of martensite was found in the CP-Ti because of low solute content and, consequently, much higher critical cooling rate. Plausible reason for some controversy found in the literature on the resulting transformation products after laser processing of CP-Ti was given. The present findings might have important industrial implications because careful microstructural characterization revealed the real position of the skin fusion line, which is of great importance for fulfillment of the weld quality criteria.
KeywordsLaser beam welding Titanium alloys T-joint Microstructure EBSD
The authors would like to thank Mr. R. Dinse, Mr. F. Dorn, and Mr. S. Riekehr from the Department of “Joining and Assessment” of Helmholtz-Zentrum Geesthacht for their valuable technical support.
This work was carried out within the framework of an EU Project and was funded by the European Union (Clean Sky 2 EU-JTI Platform) under the thematic call JTI-CS2-2014-CFP01-LPA-01-03 “Development of advanced laser based technologies for the manufacturing of titanium HLFC structures/DELASTI” (grant agreement no: 687088).
- 1.Dawes C (1992) Laser welding, a practical guide, 1st ed. Woodhead Publishing Ltd, CambridgeGoogle Scholar
- 3.Boyer R, Welsch G, Collings EW, (ed) (1994) Materials properties handbook: titanium alloys, 1st ed. ASM International, Materials ParkGoogle Scholar
- 13.AMS 4902E (1986) Titanium sheet, strip, and plate, commercially-pure, annealed 40.0 ksi (276 MPa) yield strength. SAE International. doi: https://doi.org/10.4271/AMS4902E
- 14.AMS 4911F (1988) Titanium alloy, sheet, strip, and plate, 6Al - 4V, annealed. SAE International. https://doi.org/10.4271/AMS4911F
- 15.Petzow G (1994) Metallographisches, keramographisches, plastographiches Ätzen. Gebrüder Bornträger, Berlin, StuttgartGoogle Scholar
- 16.Duley WW (1998) Laser welding. John Wiley & Sons, INC., New YorkGoogle Scholar
- 18.Salem AA (2009) Texture separation for α/β titanium alloys. In: Schwartz AJ, Kumar M, Adams BL, Field DP (eds) Electron backscatter diffraction in materials science, 2nd ed. Springer Publishers, New YorkGoogle Scholar
- 19.Banerjee S, Mukhopadhyay P (2007) Phase transformations, examples from titanium and zirconium alloys. Elsevier, OxfordGoogle Scholar
- 21.Pilchak AL, Broderick TF (2013) Evidence of a massive transformation in a Ti-6Al-4V solid-state weld. J Met 65:636–642Google Scholar
- 29.Fomin F, Ventzke V, Dorn F, Levichev N, Kashaev N (2017) Effect of microstructure transformations on fatigue properties of laser beam welded Ti-6Al-4V butt joints subjected to postweld heat treatment. In: Tanski T, Borek W (eds) Study of grain boundary character. InTech, RijekaGoogle Scholar
- 31.Murakami Y (2002) Metal fatigue: effects of small defects and nonmetallic inclusions, 1st edn. Elsevier, OxfordGoogle Scholar
Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits use, duplication, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made.