The influence of the microstructure morphology of two phase Ti-6Al-4V alloy on the mechanical properties of diffusion bonded joints

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2018-05, Vol.726, p.251-258
• Main Authors: Yakushina, E., Reshetov, A., Semenova, I., Polyakova, V., Rosochowski, A., Valiev, R.
• Format: Article
• Language: English
• Subjects: Bonded joints; Bonding strength; Coarsening; Creep; Creep strength; Deformation; Diffusion; Diffusion bonding; Diffusion welding; Grain structure; Joint strength; Mechanical properties; Microstructure; Morphology; Recrystallisation; Shear strength; Shear tests; Titanium alloy; Titanium alloys; Titanium base alloys; Vacuum furnaces
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2018.04.052

The influence of ultra fine grained (UFG) and coarse grained (CG) microstructure of the titanium alloy Ti-6Al-4V on the strength of a diffusion bonded (DB) joint was studied using a laboratory DB fixture and a new shear test rig. The DB process was carried out at 725 °C and 825 °C during 2 and 4 h in a vacuum furnace. Coarsening of grain structure resulting from different DB cycles was quantified. The chain pores were observed at 725 °C for both microstructure conditions bonded during 2 h. The increase of bonding time up to 4 h leads to subsequent elimination of the pores. The UFG samples bonded at 725 °C showed a higher level of the shear strength than CG samples for both bonding times. The CG material demonstrated the highest shear strength after 4 h of DB bonding at 825 °C. The increase of the creep deformation of UFG samples when compared to the CG condition was observed as a result of DB at of 725 °C during 4 h.