NOVEL PROCESSING OF BRAZING ALUMINUM TO ALUMINUM AND TO AUSTENITIC STAINLESS-STEEL

A new method of brazing aluminium to austenitic stainless steel involving squeeze casting has been established and has been named 'cast brazing'. Without melt flow control, strengths exceeding 40 MN m-2 were achieved for the aluminium/stainless steel joint. The presence of a porous sintered layer on the bond face of the stainless steel increased the strength of the joint to approximately 70 MN m-2. By controlling the flow of aluminium braze during casting, the formation of an intermetallic reaction layer at the interface was effectively suppressed and the strength of the brazed interface was increased to a value exceeding the strength of the aluminium. On brazing aluminium to aluminium with a preliminary nickel coating on the surfaces to be joined, interfacial strengths exceeding 50 MN m-2 were attained. Before fracture, this type of joint exhibited an elongation of up to 10%.