Filler metal for aluminum brazing sheet for heat exchangers and method of manufacturing same

• Main Authors: HASEGAWA YOSHIHARU, KASHIMA EIICHI, YAMASHITA NAOKI, SAKAI KEIICHI, HIRAO KOJI, TANI SHINICHI, NISHIKAWA HIROSHI, ITOH YASUNAGA
• Format: Patent
• Language: English
• Published: 20.03.2003
• Edition: 7
• Subjects: ALLOYS; CASTING; CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES; CHEMISTRY; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; FERROUS OR NON-FERROUS ALLOYS; MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR; METALLURGY; PERFORMING OPERATIONS; POWDER METALLURGY; SOLDERING OR UNSOLDERING; TRANSPORTING; TREATMENT OF ALLOYS OR NON-FERROUS METALS; WELDING; WORKING BY LASER BEAM

An object of the present invention is to provide a filler metal for an aluminum brazing sheet for heat exchangers capable of preventing or controlling occurrence of a melting hole during heating for brazing, and a method of manufacturing the same. In an Al-Si alloy filler metal which is clad on the aluminum brazing sheet and melted during heating for brazing, the maximum particle diameter of a coarse Si particle crystallized in the eutectic structure of the filler metal is 20 mum or less. Provided that an average value and a standard deviation in a normal distribution of the particle diameter of the coarse Si particle in the filler metal are respectively mu and sigma, (mu+3sigma) is preferably 10 mum or less. This brazing sheet is obtained by a method of adding a specific amount of Na, Sr, or Sb to the filler metal, a method of limiting the amount of impurities in the filler metal within a specific range, a method of specifying a cooling rate during the casting of the filler metal, or the like.