Diffusion bonding of grey cast iron to ARMCO iron and a carbon steel

The microstructure transformations produced during the diffusion bonding of grey cast iron to pure iron (ARMCO iron) and to a hypoeutectic steel (0.55% C) have been studied. The indirect determination of the carbon concentration profiles has produced a diffusion equation that relates the microstructure of the bond interface to the bonding temperature and time. A new tensile test specimen is described; this specimen has a variable circular section which allows the determination of true tensile strength of dissimilar diffusion bonds. Metallographic and fractographic studies have shown that the optimum bonding conditions for both types of joint are a bonding temperature at 980° C, for 5 min at a bonding pressure of 4.5 MPa.