For arc welding Aluminum alloy 6061-T6 two welding alloys are used: 5356 and 4043. Their counterparts in accordance with GOST 4784 and GOST 7871 - SvAMg5 and SvAK5. Each has advantages and disadvantages depending on their usage conditions.
Strength or ease of welding?
As the aluminum alloy, comprising 5 % magnesium, alloy 5356 usually more durable and plastic, than an alloy 4043. However, the alloy 4043, which contains 5 % silicon, It has better flowability, better resistance to cracking, greater ease of welding, a lower tendency to form a dark welding deposit and the weld gives more aesthetic appearance.
Heat-affected zone of the weld
The question arises: if the alloy 5356 stronger, then can it not always be applied? Answer: no. although the alloy 5356 and stronger, than 4043, they are both stronger, than the weakest portion of the so-called "heat affected zone" butt weld alloy 6061-T6. This breaks the weld in this zone - is not at the weld - and the strength of this zone does not depend on the used welding alloy.
Another situation arises for fillet welds. These welds are more likely to work on a shift, rather than the tensile, as the butt joints. Fillet welds are almost always destroyed by the weld metal, and then can go rafting 5356, which has a shear strength almost a half times higher, than an alloy 4043.
Stress corrosion cracking
In the same time, alloy 4043 It is less prone to cracking, than an alloy 5356. If the weldment is thermally treated after welding, it is necessary to apply the alloy 4043, since the alloy after heat treatment 5356 It may be prone to stress corrosion cracking. Similarly, if the weldment is operated at a temperature above 65 ° C, be applied Alloy 4043 avoid stress corrosion cracking.
However, if the product will be exposed after welding anodizing, it is best to apply the alloy 5356. The high content of silicon alloy 4043 It will cause dark weld, that will make it visible and unattractive. Alloy 5356 proanodiruetsya in silver.
A source: F. Armao, www.thefabricator.with