1985 Volume 3 Issue 4 Pages 690-696
The heat source of resistance brazing is electric resistance heating. Therefore the same principles as those for other resistance welding are considered to be applied. However the mechanism of heating and the correlation between the brazing conditions and the strength of brazed joint are less known. It is interesting to investigate the problems of brazing process from the view point of resistance welding process. The authors made small braze area on lap joint specimens similar to resistance spot welding, then tested and analyzed the effects and correlation between elements of resistance brazing condition comparing with those for resistance spot welding. Thus the following fundamental data has been obtained.
The behavior of resistance brazing is very similar to that of resistance spot welding. The correlation between the elements of condition has similar characteristics. The strength of braze increases in proportion to brazing current and brazing time. When the increase rate is saturated, fusion zone similar to nugget of spot weeding is formed. When this phenomenon appears, the strength per a unit area decreases rapidly. And the base metal is heat affected.
Resistance brazing is operated relatively easily, and strength obtained is stable and reliable with optimum schedules.
The voltage drop characteristics at the brazed area observed with an oscillograph is vrey similar to that of resistance spot welding. By analyzing it, it becomes possible to choose appropriate conditions of brazing and control the operation.
The choice of electrode is important. Carbon graphite is of low cost, but has the following shortcoming. The magnitude of current varies remarkably depending on its size, especially decreases exponentially with increase in the thickness.
The surface of material to be brazed and electrode sticks to each other owing to temperature increase before the current duration to obtain the maximum tensile shear load is reached, which. causes a problem in practical operation.
