Comparison between brazing properties of stainless steel to various aluminium alloys

Brazing of Stainless Steel to Various Aluminum Alloys in Air

“…Though it is not easy to observe from this photograph, no marks of the brazing filler metal to have adhered on the stainless steel surface was observed, despite that the discoloration at several parts was seen on the surface of stainless steel. On the contrary, on the surface of the aluminum alloy, the traces of the reaction between the brazing filler metal and the base metal, and those of the absorption of the brazing filler metal into the base metal are observed (6) . Table 5 shows the results of EDX analysis on the brazing filler metal layer of the SUS304/A1050 joint formed at the brazing temperature of 888 K for 30 s. It also shows the results on the surface of the A2024 side of SUS304/A2024 assembly which was failed to join at the brazing temperature of 888 K for 30 s. In the result of the SUS304/A1050 joint, Si and Zn are detected besides the constituent elements which had diffused from both of the aluminum alloy side and the stainless steel side into the joint interface layer.…”

“…At the brazing temperature of 868 K, the brazing joints of A1050, A2024 and A6061 to stainless steel were formed. When the brazing temperature was raised step by step to 898 K, though the good joint was obtained at every temperature for A1050, the temperature range to form the brazed joint was not simple for other aluminum alloys (6) . During the brazing process in air, the lack of flux is always concerned.…”

“…The Zn originated from the flux is detected in the reacted layer. The formation of the thick intermetallic compound phase causing the brittleness of the interface was at least not recognized (6) .…”

“…Some part of Cr in the stainless steel may become the oxide. But, the intermetallic compound phase formed on the stainless steel side interface has only several µm thickness, and it is thought that the possibility for it to enbrittle the brazing interface is very small (6) . Though the strength test for the brazed joint is waited for, the above microstructure observation and the elemental analysis results are considered to show that the sufficiently strong brazed joint of the aluminum alloys to the stainless steel can be formed when the stainless steel surface is wetted before brazing to the aluminum alloys.…”

“…The behavior of constituents of aluminum alloys, stainless steel and the flux at the brazing interface was examined. The final aim of this research is to find the suitable brazing conditions between the aluminum alloys and the stainless steel in air (6) .…”