What should you pay attention to when welding stainless steel and copper?
The most abundant metal in stainless steel is iron. Both iron and copper have limited solid solution in the solid state, but show infinite solid solution in t
The most abundant metal in stainless steel is iron. Both iron and copper have limited solid solution in the solid state, but show infinite solid solution in the liquid state, and no intermetallic compounds will be generated. The atomic radii, lattice constants and lattice types of iron and copper at high temperatures are very similar, so this is beneficial to welding between iron and copper. However, in general, iron and copper are two different metals with considerable differences in physical and chemical properties, so there are still many difficulties during welding.
There are four main welding processes that can usually be used when welding copper and stainless steel. The first is manual arc welding, which requires a DC welding machine and uses a copper electrode to weld first. The copper alloy usually needs to be pre-welded before welding. hot. The second type is gas welding, which is brazing. Silver wire with a silver content of more than 35% is usually used for welding processing. It is mainly suitable for thin or small parts. However, this method has a higher silver content, so the cost will be higher. , the alternative is to use MG130 welding wire, which is relatively cheaper, but the disadvantage is that there are too many fakes of this kind of welding wire in the market.
The third type is argon arc welding, which uses silver welding wire or low silver copper welding wire for welding processing, and uses a DC argon arc welding machine. The fourth type is low-temperature brazing, which uses low-temperature brazing material for welding processing. This is suitable for scenarios where strength requirements are low and the equipment operating temperature is not high.
Arc welding is a relatively common stainless steel welding process. When welding stainless steel and copper, taking advantage of the infinite solid solution characteristics of iron and copper, nickel or nickel-based alloys are used as filler materials, and the welding quality will be better. Yes, if you use pure copper wire, it will easily cause cracks and embrittlement. Because copper metal dissipates heat much faster than stainless steel, when welding stainless steel and copper, the arc should be biased toward the copper side.
Liquid copper or copper alloy has a strong penetration effect on the crystallization boundary of stainless steel in the near-seam area, and penetration cracks will form under the action of tension. Single-phase austenitic stainless steel is very easy to form hot cracks, while duplex austenitic stainless steel is very easy to form hot cracks. Relatively difficult to form penetration cracks.