A chromium-nickel steel for seamless tubes used in the nuclear power industry

The claim concerns steel containing up to 1.5% manganese, up to 0.8% silicon, 17 to 19% chromium, 10 to 11% nickel, up to 0.035% phosphorus, up to 0.02% sulfur, up to 0.05% nitrogen, up to 0.025% cobalt, and up to 0.3% copper, and it is proposed that the steel contain 0.03% to 0.05 wt.% carbon and 0.25 to 0.45 wt.% titanium. Owing to the reduction in the carbide-forming element contents, the occurrence of tiny TiC precipitates, hindering the recrystallization process, decreases substantially. The structure of tubes which are manufactured from the steel by hot forming on a pilger mill train thus improves, and the formation of elongated unrecrystallized grains is restricted. The mechanical properties of the tubes are very good as well. (J.B.)