Copper-Zinc Dezincification
Copper-zinc dezincification is selective corrosion of brass where zinc is leached out, leaving a porous, copper-rich residue. This leads to loss of mechanical integrity.
Physicochemical mechanism of action
Copper-zinc dezincification is a chemical reaction between brass (an alloy ratio of copper and zinc) and a corrosive medium, such as air or water. During the corrosion process, zinc is preferentially leached from the alloy because it is more reactive than copper. This results in zinc being dissolved, for example by chloride ions (e.g., sulfuric acid), and a copper-rich residual structure remains.
Metallurgical relevance & welding risks
Dezincification can lead to a significant change in the weld structure. The porous, copper-rich residual structure is less mechanically stable and loses its toughness and strength. This increases the susceptibility to cracking and hot cracking. Furthermore, dezincification damage can significantly reduce the service life of components.
Workshop practice & instructions
To avoid copper-zinc dezincification, brass components should be thoroughly cleaned and dried before welding. When selecting the welding process, make sure it is suitable for brass and does not cause additional corrosion. Proper cooling after welding can also help prevent or limit dezincification.