Impulse pressuring diffusion bonding of titanium alloy to stainless steel

Impulse pressuring diffusion bonding between a titanium alloy TA17 and an austenitic stainless steel 0Cr18Ni9Ti has been carried out in vacuum. Relationships between the bonding parameters and the tensile strength of the joints were investigated, and the optimum bond parameters were obtained: bonding temperature T = 825 °C, maximum impulse pressure Pmax = 50 MPa, minimum impulse pressure Pmin = 8 MPa, number of impulses N = 30, impulse frequency f = 0.5 Hz. The maximum tensile strength of the joint was 321 MPa and the effective bonding time was only 180 s. The reaction products and the interface structure of the joints were investigated by optical microscopy, scanning electron microscopy (SEM), electron probe microanalysis (EPMA), and X-ray diffraction (XRD). The study revealed the existence of FeTi, Fe2Ti, σ phase and β-Ti in the reaction zone. Brittle Fe–Ti intermetallic phases lower the strength and ductility of the impulse pressuring diffusion bonded couples significantly. This technique provides a reliable and efficient bonding method of titanium alloy and stainless steel.