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Metallurgical aspects of joining commercially pure titanium to Ti-6Al-4V alloy in a T-joint configuration by laser beam welding

  • Fedor Fomin
  • Martin Froend
  • Volker Ventzke
  • Pedro Alvarez
  • Stefan Bauer
  • Nikolai Kashaev
Open Access
ORIGINAL ARTICLE
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Abstract

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.

Graphical abstract

Keywords

Laser beam welding Titanium alloys T-joint Microstructure EBSD 

Notes

Acknowledgements

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.

Funding information

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).

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Copyright information

© The Author(s) 2018
corrected publication [August/2018]

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.

Authors and Affiliations

  1. 1.Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Materials MechanicsGeesthachtGermany
  2. 2.Institute of Product and Process InnovationLeuphana University of LüneburgLüneburgGermany
  3. 3.Department of Joining ProcessesIK4-LORTEK, Technological CentreOrdiziaSpain
  4. 4.Department of Future Industrial SystemAirbus Operations GmbHBremenGermany

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