Effect of pressure pulsation on bond interface characteristics of 409 ferritic stainless steel diffusion bonds

In present study, impulse pressure assisted diffusion bonding (IPADB) technique was applied for diffusion bonding of 409 ferritic stainless steel plates. The effect of diffusion bonding process parameters i.e. maximum pulse pressure and pressure pulses on bond interface characteristics and mechanical properties was investigated. The bonds were analyzed by field emission scanning electron microscope (FESEM) and using these micrographs interface bonding ratio was measured, which is defined as the ratio of void free interface length to the total interface length. The pressure pulsation improved the interface bonding ratio by reducing the voids at the interface. At 40 MPa maximum pulse pressure and 18 pressure pulses, 43.7% improvement in interface bonding ratio of the diffusion bonds was observed with respect to those developed at same constant pressure. Hardness and tensile shear tests were performed on the diffusion bonds. A maximum shear load of 37 kN was obtained for the diffusion bonds developed at 40 MPa maximum pulse pressure and 18 pressure pulses, having the fracture from the base metal during tensile shear testing. The fracture surface of the diffusion bonds was also studied by FESEM.