The best metals for welding depend on the project design and budget, the skill and experience of the welder, and the welding process to be used. Almost any metal can be welded, but some are easier than others for creating a high-quality, defect-free weld.
Some types of metal require special equipment, such as a vacuum or gas chamber, limits on heat exposure, or pre- and post-welding heat treatment. Some perform better with different types of welding, whether stick, TIG, or MIG. Choosing the right electrode and filler material for the base metal and following prescribed welding procedures is essential. Each specific situation depends on the base metal’s chemical makeup.
Low Carbon Steel
Also known as mild steel, low carbon steel contains a very small percentage of carbon (less than 0.3%) and up to about 0.4% manganese (AISI 1018 steel). This commonly used steel is very ductile, due to its low carbon content. High ductility means high weldability because it reduces the chance of brittleness in the heat affected zone (HAZ), which can lead to hydrogen cracking. Low carbon steel can be welded using almost any type of equipment and is one of the best metals for welding.
Stainless steel can be quite weldable, depending on the grade. Ferritic and austenitic stainless steels can be welded fairly easily, but not martensitic stainless types, which tend to crack. Stainless steel tends to warp under high heat, which can affect the shape and strength of the final workpiece. Another issue is that the chromium in stainless will combine with carbon during the welding process, leaving the piece more susceptible to rust without its chromium oxide protective layer. To prevent this problem, don’t heat the workpiece above the recommended temperature, or choose a low-carbon stainless grade.
Creating a defect-free weld in aluminum is different than welding steel, but can be done by following the prescribed guidelines. Choosing the proper grade is important, as some types are much easier than others to weld. Because of aluminum’s high thermal conductivity, heat is transferred away from the weld very quickly. Equipment with a higher welding current may be required to supply the necessary heat. As it cools, aluminum shrinks significantly more than steel, so special care must be taken to prevent craters and cracking. Finally, the natural aluminum oxide coating on the base metal can add contaminants, and should be removed prior to welding to avoid porosity in the weld.
Other Metal Types
Other metals, including magnesium, copper, cast iron, titanium and superalloys such as Inconel, can be welded. These will typically require special equipment and expert skill, making them less weldable for traditional job shops and hobbyists.
Industrial Metal Supply is your one-stop shop in the Southwest for all things metal. Visit our catalog for a wide selection of metal products, including steel, stainless steel, and aluminum, as well as all the machines, supplies, and accessories you need for welding.