Gas Brazing AluminiumGas brazing may be used to join aluminium and aluminium alloy. Its application is usually to sheet material, extrusions and some castings. When gas brazing aluminium acetylene is used as the fuel gas and a neutral flame should be used. Consumables for gas welding include the filler rods and fluxes. The most frequently used filler rod for brazing is Al-10 to 13%Si as this has the lowest melting point. It is suitable for most alloy compositions except those high in magnesium. A flux must always be used to remove the tenacious surface oxide to allow 'wetting' to take place. These fluxes are very aggressive and corrosive and must be thoroughly washed off once the job is complete. The main problems encountered during brazing of aluminium are due to poor surface wetting and poor flow of filler. This can be overcome by improving joint fit-up, adequate heating and correct use of flux and filler rod. The main potential safety hazards are fire, explosion, and corrosive fluxes. Fume generation is normally low.
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