QQ-B-654A

Abstract

This specification covers silver-containing brazing alloys for the brazing of ferrous and nonferrous base metals. <b><u>Intended Use:</u></b> BCuP-5 classification of brazing alloy is of the copper-phosphorous alloy type. It is intended for joining copper and copper-base alloys. It is not intended for joining ferrous or nickel base alloys. BAg-4, -5, -7, -8a, -9, -10, -13a, -18, -20, -22, and -23 classification of brazing alloy are of the silver alloy type with no cadmium added. They are intended for joining most ferrous and nonferrous metals, except aluminum and magnesium. BAg-5, -9, -10, and -20 classification of brazing alloy are of the silver-copper-zinc alloy type. They are used for brazing copper and copper alloys and have good wetting and flow characteristics. BAg-4, -13a, and -22 classification of brazing alloy contain nickel which improves the wetting of tungsten carbide and are used for carbide tip brazing. In addition, BAg-13a has no zinc additions made to it; its use is advantageous when zinc volatilization is objectionable in furnace brazing operations. BAg-7 and -18 classification of brazing alloy contain tin. BAg-7 has good wetting properties for nickel and nickel base alloys. BAg-18, with a higher tin content, has good wetting properties for stainless steel, nickel, and nickel base alloys and carbon steel. BAg-8a classification of brazing alloy contains lithium which promotes wetting of difficult-to-braze metals and alloys. This brazing alloy is used to braze precipitation-hardening and other stainless steels in the 1400&#176;F and 1600&#176;F range. BAg-23 classification of brazing alloy is a silver-manganese alloy with no other elements intentionally added. It is used in brazing stainless steel, cobalt base alloys, nickel-chromium, iron alloys and complex carbides, particularly where high service temperatures are encountered. Grades IV, V, VI, VII, and VIII classification of brazing alloy are of the cadmium-containing silver alloy type. They are currently intended for joining the metals in 6.1.2. Their use was previously preferred because of their low brazing temperature range and satisfactory service performance. However, poisonous fumes are produced on heating these brazing alloys which makes their use objectionable for brazing operations. They will be deleted from QQ-B-654 when substitute brazing alloys have been evaluated for satisfactory service performance. <br>