High-integrity diffusion bonding of laser powder bed fused, forged, and rolled Ti–6Al–4V alloys

Abstract

Diffusion bonding of additively manufactured Ti–6Al–4V components with complex geometries to conventionally processed frames is a cost-effective approach for reducing the buy-to-fly ratio while minimizing deformation. This is the first study to investigate the diffusion bonding between laser powder bed fusion (LPBF)-manufactured and conventionally processed Ti–6Al–4V alloys at various temperatures, durations, and pressures. Herein, the diffusion bonding of forged, rolled, and LPBF-manufactured Ti–6Al–4V alloys were examined under specific bonding conditions: 900 °C for bonding durations of 1 and 2 h and pressures of 2 and 4 MPa. Extended bonding durations led to β phase coarsening and thickened, elongated α′ laths in LPBFed materials, negatively impacting their mechanical properties. Optimal bonding was achieved at 900 °C for 2 h under 4 MPa, with bonding ratios exceeding 97%. Although LPBFed materials exhibited higher porosity than conventional alloys, which slightly reduced the bonding strength, microhardness and tensile testing revealed comparable bonding strengths. However, the LPBFed samples exhibited smaller elongation owing to the surface porosity. These findings suggest that diffusion bonding between LPBFed and conventional Ti–6Al–4V alloys can maintain mechanical integrity while reducing material waste, which presents a viable solution for aerospace component manufacturing.

Keywords

• Ti–6Al–4V
• Diffusion bonding
• Laser powder bed fusion
• Microstructure
• Mechanical properties