Effect of surface finish and sheet thickness on isostatic diffusion bonding of superplastic Ti-6Al-4V

Abstract

The aim of the present work was to determine the process conditions of pressure, temperature, and time required to produce high quality isostatic diffusion bonds in Ti-6Al-4Vfor two surface finishes. In addition, the conditions to produce a sound bond between two sheets or plates of Ti-6Al-4V having different thicknesses were investigated. An assessment of the quality of bonds produced was made on the basis of metallographic examination, lap shear strength measurements, and SEM examination of the shear fracture surfaces. Sound bonds were produced in the as received and pickled 1.6 mm thick sheet in under 1 h with an applied pressure of 2.1 MPa at both 940 and 920°C and for the P60 ground surface finish at 940°C, but the time increased to 1.5 h at 920°C for the coarser surface finish. Variations in sheet thickness from 1.6 to 10 mm were found to have no effect on the bonding time. These results were compared with the predictions of a model of isostatic diffusion bonding.