Numerical modelling and experimental investigation of diffusion brazing SS304/BNi₂/SS304 joint

The kinetics of dissolution and isothermal solidification at the bonding temperature during diffusion brazing SS304/BNi-2/SS304 has been studied through a combination of analytical modelling and experimental investigations. The modelling Is based on the diffusion theory and the consideration of transient motion of liquid/solid Interface. A set of coupled finite differential equations has been programmed to track the motion of liquid/solid interface during the isothermal solidification of liquid filler. Four parameters can be mathematically determined from the analytical modelling including the evolution of solute concentration profile, the maximum diffusion distance, and the maximum liquid thickness as well as the time to complete the isothermal solidification. These analyses are helpful to understanding the joining mechanism during diffusion brazing. The temperature dependent diffusion coefficient used in the modelling Is derived together with the experimental data from brazing the wedge shaped joint specimen of SS304/BNI-2/SS304. The effects of bonding temperature and Initial joint thickness on the joining process have also been investigated.