Inhibition of intermetallic formation during diffusion bonding of high-carbon steel

Diffusion bonding of high-carbon steel was carried
out in vacuum brazing furnace at temperature 900–
1,050 °C for 0.5 h under uniaxial load using Ni foil interlayer.
Microstructure of assemblies was studied along with
effect of diffusion of chemical species in reaction zone and
mechanical properties. Microstructure of substrate was
changed from martensite to austenite at bonding temperature
and subsequently to ferrite–pearlite during cooling to ambient
temperature. Diffusion zone did not exhibit formation of
any intermetallic compounds. Bond strength was governed
by degree of solid solution hardening and contact area of
mating surfaces depending on joining parameters. In this
respect, maximum ultimate strength of ~532 MPa was
obtained along with shear strength of ~792 MPa for the
joint processed at 1,050 °C, which was higher than literature
reports on martensitic steel.