Study of metallurgical and mechanical properties of CSEF P92 steel diffusion bonds developed using pressure pulsation

Abstract

For developing a diffusion bond with excellent mechanical properties, highly polished surface is required. These polishing requirements makes the process slow and less productive. So, in present investigation, creep strength enhenced ferritic (CSEF) P92 steel specimens were diffusion bonded with high surface roughness using impulse pressure assisted diffusion bonding technique. These pressure pulses create plastic deformation, break the oxide layer and reduce the voids at the interface. Sound joints were obtained at 1000 °C bonding temperature, 10 min pulsation time, 10 s pulse duration under 20 MPa maximum pulse pressure for 60 min bonding time. The integrity of the developed joints was examined by metallurgical and mechanical characteristics in as-bonded and post diffusion bond heat treated (760 °C/2 h) conditions. It was found that diffusion bond was free from voids and the bond line appeared like a grain boundary. A maximum tensile strength of the diffusion bonds was found as 1439 MPa in as-bonded condition having failure from base metal far away from the bond interface. V-notch Charpy impact toughness of the diffusion bond was found to be improved after post diffusion bond heat treatment.