Chromium and Chromium Alloys

Various alloying additions have been discovered which render unalloyed chromium much less susceptible to low-temperature embrittlement as well as to nitridation in air at elevated temperatures. These include additions of the Group IIIA metals, magnesia, and carbides based on the Groups IVA and VA metals. Of these additions, only the carbides contribute significantly to the hot strengthening of chromium. The combination of selected carbides and solid-solution-strengthening elements such as tungsten, molybdenum, and/or tantalum, has resulted in experimental alloys which retain useful strengths at temperatures through 1316 C (2400 F). These high strengths are achieved at some sacrifice in the low-temperature ductility of chromium. Also, despite the improvements afforded in the oxidation and nitridation resistance of chromium through alloying, no alloys are available which are capable of service in long-time exposures in air above 982 C (1800 F) without suffering some property degradation.