Vacuum brazing of 304 stainless steel plate-fin structure and simulation of its tensile strength

The impacts of the vacuum brazing conditions, including the filler metal thickness, pressure, and heating/cooling modes, on the tensile strength of the 304 stainless steel plate-fin structure, were experimentally studied and analytically simulated in finite element method. Both the measured and calculated results show that the filler metal thickness strongly affects the tensile strength of the plate-fin structure. For instance, as the filler metal thickness increases in the three ranges: below 105 μm, 105 μm to 140 μm, and beyond 140 μm, the tensile strength first increases, then, remains unchanged, and finally, decreases, respectively. Besides, a thickness increase leads to the increases in the fillet area and load, which in turn, enhance the tensile strength, generate more brittle phases in the fillet, and reduce the bonding strength at the junctions.