For aluminium alloy brazing, the choice of filler metals is not as broad as for brazing other non-ferrous metals. The ALUSALD 12 alloy is the most widely used, though it requires skilled brazing. The addition of silicon reduces the melting temperature of the filler metal, which would otherwise be the same temperature as the base metal, making brazing impossible. These types of alloys can also be used in TIG welding.
These alloys can be used for brazing pure aluminium and its alloys, which must not, however, contain more than 1% magnesium, 1.5% manganese and 1.25% silicon.
Due to the difficulties connected with aluminium brazing, ALUSALD 2 and ALUSALD 22 alloys are increasingly used and are composed of aluminium and zinc in different ratios. These alloys, having a lower melting point than the operating temperature of the base metal, reduce process risks, especially in maintenance and aluminium-copper brazing.
|Name||ISO17672||ISO3677||Temp. Fusion °C|
|ALUSALD 12||88||12||-||Al 112||-||c.a. 575 - 585°C|
|ALUSALD 2||2||-||98||-||S-Zn92Al2||c.a. 376 - 385°C|
|ALUSALD 22||22||-||78||-||S-Zn78Al22||c.a. 426 - 482°C|