Abstract: Rolling-diffusion bonding experiments were performed on steel Cu steel system using 50 μm thick copper as interlayer.The effect of plastic deformation on bonding strength and interlayer thickness was investigated.Based on experiments, the kinetics of isothermal solidification was systematically studied.And a numerical model of isothermal solidification time was developed.The results show that the isothermal solidification time is obviously reduced due to the effect of plastic deformation.A reasonable isothermal solidification time was obtained when an effective diffusion coefficient was used, indicating the intercrystalline and grain boundary diffusion of Cu in steel play an important role.The evolution of interlayer thickness indicates a good agreement between the calculation results and experimental measurement.