Braze Pressure Welding (BPW)-A New Method for High Quality Pressure Welding

Braze Pressure Welding (BPW) with high frequency induction heating has been invented as the new joining method for welding general steel pipes for on-site piping without the danger of fire and the dispersion in the joint properties due to welder's skill. In the BPW, a brazing filler is interlaid between the mating surfaces to be joined. The filler melts by heating up to joining temperature, then the welding pressure discharges it from the joining interface. At the same time, the base metals are pressure-welded to each other, and that the discharged liquid filler forms fillets around the joining area. The fillets have the effects both on relaxing the stress concentration at the joint and on increasing the joining area, which contributes to the strengthening of joint. Experimentally it was revealed that the BPW joints had superior properties to brazed or pressure-welded joints by microscopy, EDS analysis, and tensile test of joints. The effect of the fillet on relaxing the stress concentration at the joint area was also confirmed by finite element analysis.