Joining steel tubes employing Fe-Si-B metallic glasses as filling material

Bonding of seamless, low carbon, steel tubes were performed by means of a transient liquid phase bonding (TLPB) process employing a Fe-Si-B glassy metal as filling material. The butt joints were performed by induction heating under a moderate pressure and argon flux. Thermal cycles consisting of a fast heating followed by an isothermal stage and ending with a controlled cooling down to room temperature were applied. The isothermal stages performed for a time t at temperature T (TW < T < TT with TW and TT the melting temperature of the glassy metal and the tube materials respectively). The microstructures of the joint zones were analyzed employing optical and scanning electronic microscopy, energy dispersive X-ray and electron probe microanalysis. The diffusion of the elements during the process was studied. The bonding process was modeled in order to determine the Si distribution for different length of the isothermal stage. The results from modeling are compared to the experimental data and the bonding process is discussed. C 2005 Springer Science + Business Media, Inc.