The metals which are very ductile can be cold-welded. This technique is very useful to join aluminum, especially grades like the 7XX series which are otherwise unweldable. The brass alloy in 70/30, zinc, copper, nickel, silver, silver alloys, and gold, as wires. Cold welding can join metals such as stainless steel, after applying great pressure. Carbon-containing metals can not be cold-welded.