Cu in CA6NM martensitic stainless steel

Cu has a weaker effect on the formation of austenite. A small amount of Cu addition can not optimize the martensitic microstructure of martensite. In the corrosive medium, Cu can form an enrichment layer under the oxide layer of the steel. thereby preventing the FeO from continuing to penetrate into the interior of the metal. Thus the addition of Cu into super martensitic steel can improve the corrosion resistance of steel in hydrochloric acid and sulfuric acid. And also improve the stress corrosion resistance. However, excessive Cu content can cause embrittlement of copper during hot working.