M. Mazar Atabaki, Tehran University, Tehran, Iran
This work investigates the effects of variation parameters on the joints quality. Brazing is a convenient method for joining of copper–beryllium alloys to copper-beryllium alloys or pure copper components with a thickness less than 0.2mm. This joining process provides the possibility of brazing and heat treatment operation simultaneously. In this research copper-beryllium foil were brazed to copper-beryllium or pure copper components by Ag based filler metals. These fillers reached to appropriation dimension with rolling. Original components were joined with scheme of lap joint by using furnace brazing method in argon or a vacuum atmosphere according to ASTM and ASME standards. The quality of joints was optimized by changing filler, flux, and temperature and operation time. Mechanical property and strength of joints were measured by micro hardness, tensile and fatigue testing. The results showed that the temperature of heat treatment and brazing have the most significant effect on hardness aging of components. The formation of oxide film was limited only in presence of a vacuum less than 10 -5 torr. The results showed that the shorter time cycle lead to increase in tensile and fatigue strength of lap joints. In this study microscopic examination of joints interfaces show that a uniform structure made by both solid and inter metallic compounds.
Keywords: Brazing; Copper Beryllium alloy; Spreading factor; Vacuum furnace; Precipitation; Aging
