Effect of interface surface profile on the microstructure and tensile properties of hot isostatically diffusion bonded Ti-6Al-4V

Solid-state joining has been performed using Hot Isostatic Pressing/Diffusion Bonding (HIP/DB) for Ti-6Al-4V solid-to-solid and solid-to-powder combinations to investigate the microstructure and tensile properties of the HIP/DB structures with different interface surface profiles. Three combinations were considered in this work; the first was solid-to-solid with interfaces ground with Silicon Carbide (SiC) P1200 grit paper, the second was solid-to-solid with interfaces ground with SiC P2500 grit paper and the third was solid-to-powder Ti-6Al-4V with interfaces chemically etched using Kroll's reagent. HIP/DB was carried out in the (α + β) phase field region using identical HIP parameters. Microstructural characterisation was subsequently performed for the HIP/DB interfaces using scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD) to assess the extent of recrystallisation at the interface. The tensile properties were also evaluated at room temperature (RT). It was found that HIP/DB resulted in increased recrystallisation and intergrain misorientation at high asperity interfaces and RT tensile properties that were comparable to the properties of the extruded Ti-6Al-4V parent material.