Conclusion: Welding brass onto aluminum requires a few special considerations due to their different melting points, but it can be done successfully with proper preparation and technique! Be sure that all surfaces are clean before beginning work; this will help ensure strong bonding between pieces once completed.
Thankfully, Super Alloy 1 makes easy work of aluminum repair, enabling this one multi-metal solder to repair not only brass and aluminum, but a host of other metals–individually or in any combination: bronze, steel, copper, pot metal, stainless, white metal, or zamak in any combination, at 350°F.
Both aluminum and steel are very weldable metals. There are no problems whatsoever in welding steel to steel, and aluminum to aluminum.
Steel And Aluminum Should Not Be Welded To Each Other Directly. It is never a good idea to try to weld aluminum and steel together directly. Steel and aluminum alloys have very distinct metallurgical and physical properties, and cannot be joined directly. Firstly, steel has a much higher melting point than aluminum.
Stress cracking can occur when an aluminum weld cools and excessive shrinkage stresses are present during solidification. This could be due to a concave bead profile, a too slow travel speed, a highly restrained joint, or depression in the end of the weld (crater crack).
It's not a good idea to directly arc weld disparate metals directly to aluminum. Welding a metal such as magnesium, titanium, copper or steel directly to aluminum is very difficult to do. This is because, when aluminum is melted by the high heat of arc welding, brittle “intermetallic” compounds will form.
A good way to reduce corrosion is to use an isolating coating or paint on the aluminum and the steel to isolate them electrically. Insulating washers are also effective in isolating the two dissimilar materials and creating a relatively safe surface area.
The first is to use an aluminium coating on the steel. This can be achieved by dipping the steel into molten aluminium (hot dip aluminising). Once coated, the aluminium can be arc welded to the aluminium coating.
Insulating The Two Metals From Each Other
If left unprotected, underground copper or brass lines can be rotted out by galvanic corrosion. To insulate these metals, PVC or plastic irrigation tubing can be used. Paints, coatings, oils, and greases can also be used.
Soldering aluminum is not like soldering copper; it's not enough to just heat up and melt the solder. Even with the right flux and solder combination, you won't achieve soldering if the aluminum isn't hot enough to accept the solder alloy.
Soldering aluminum is not as easy or straightforward as soldering copper or other metals. This is because aluminum has a high affinity for oxygen which makes it difficult to form a good solder joint. However, with the right tools and techniques, it is possible to solder aluminum using a soldering iron.
The aluminum will corrode more because it is more anodic than brass, and will also corrode where it contact the brass since brass is more cathodic. In this case there should be a barrier between the brass and aluminum, with the selection of a bolt that is compatible to both materials.
Melting Temperatures of Common Metals
These are the melting temperatures of common metal types: Aluminum: 660°C (1220°F) Brass: 930°C (1710°F)
When it comes to stainless steel (301, 304 and 310) and brass, they are only two metals apart, which means they can be safely connected together with minimal risk of galvanic corrosion.
The aluminum will also corrode where its exposed surface contacts the brass plate because brass is more cathodic. A Plating Compatibility Chart is provided below that may be used to aid with fastener selection based on galvanic reaction.
Minimizing Galvanic Corrosion
Contact between dissimilar metals should always be avoided. If contact cannot be avoided, the adjacent surfaces should be painted with bituminous paint or zinc chromate primers or paints. Taping or gasketing with non-absorptive materials is also effective.
Modern engineers found a more effective solution to Lady Liberty's problem. They used PTFE (Teflon is the most common PTFE) polymer resin tape to isolate the different metals. This new type of barrier proved to be nearly impervious to corrosion.
Material thickness: Most reputable MIG machines can be used to weld aluminium down to 3mm thickness. To successfully weld materials thinner than 3mm, it may be neccessary to use specialist MIG or TIG welders with pulse capability. (Note: to TIG weld aluminium, you will need an "AC/DC" machine such as the 202T).
The right Welder is essential if you're going to work with aluminum. For aluminum, a TIG – tungsten inert gas – welding machine is a better choice than a MIG machine. While MIG machines can be used, TIG machines are preferred by most professionals taking on complex aluminum welding tasks.
The author notes that four of the most difficult metals to weld are aluminum, cast iron, brass, and stainless steel.
Welding metal type Non-ferrous metals (copper, aluminum, titanium, etc.) welding medium carbon steel, high carbon steel, alloy steel and other materials are difficult to weld.
It is possible to weld dissimilar metals. However, there are many factors that must be considered to ensure the formation of a joint with adequate strength for the intended application.