Transient liquid phase diffusion bonding with two-step heating process

This paper describes a novel transient liquid phase(TLP) diffusion bonding model recently developed for bonding T91 steel pipes.The method is based on imposing a short-time high heating temperature before the isothermal solidification of the liquid layer.The method reliably produces bond which tensile strengths as high as those of the parent material.Consequently,bonding strength is increased possibly due to the higher metal-to-metal contact along the non-planar bond lines as compared to the planar bond lines associated with conventional TLP diffusion bonding.The testing results showed that the solidified bond should consist of a primary solid solution with a composition similar to that of the parent metal and free from precipitates.Bonding parameter of new process are at 1 270 ℃ for 0.5 min and 1 230 ℃ for 3 min.Conventional bonding parameter is 1 250 ℃ for 3 min.