Effect of pipe diameter on fillet formation during brazing of aluminum pipe and sheet

Abstract

Effect of curvature of convex and concave planes on the fillet size formed after brazing of aluminum was investigated in relation to the brazing method. The fillet size was measured by throat thickness and vertical fillet leg length on the inside (concave plane) and outside (convex plane) of an aluminum pipe braze specimen. Fillet size estimated by the Laplace's equation was larger on the inside than that on the outside. In vacuum brazing inside fillet was larger than outside one under limmited test conditions, while in dip brazing inside fillet was always larger than outside one, which agreed well with the prediction of the Laplace's equation. The discrepancy between the calculation and experimental results in vacuum brazing was attributed to the poor flowabilty of molten filler metal.