Super plastic forming brazing process for Inconel 718 superalloy components

A new method, combining superplastic forming (SPF) and the brazing process, has been proposed for the production of complex-shaped Inconel 718 components. The SPF/brazing process has been used as a substitute for superplastic forming with concurrent diffusion welding process in which welding pressure cannot be applied effectively. The SPF/brazing process can also shorten the total working time and save energy during fabrication. Using this method, an Inconel 718(1) superalloy sheet was superplastically formed and concurrently brazed with a nickel-based filler metal, MBF-20(2). The working parameters were as follows: superplastic forming was done at 985 degrees C under an argon pressure of 2.45 MPa and the temperature increased to 1040 degrees C for 10 minutes for brazing. The effect of pressure on the brazement during the SPF/brazing process was simulated on a single lap shear test specimen. The results show that the joint strength in creased from 784.2 +/- 10.4 MPa to 868.4 +/- 12.5 MPa as the pressure applied increased from 0 to 2.45 MPa.