An ultra supercritical boiler tubing alloy characterized by a microstructure stabilized and strengthened for 375 bar/700.degree. C. steam, in weight percent, service and alloyed to resist coal ash/flue gas corrosion for 200,000 hours consisting of 10 to 24 cobalt, 22.6 to 30 chromium, 2.4 to 6 molybdenum, 0 to 9 iron, 0.2 to 3.2 aluminum, 0.2 to 2.8 titanium, 0.1 to 2.5 niobium, 0 to 2 manganese, 0 to 1 silicon, 0.01 to 0.3 zirconium, 0.001 to 0.01 boron, 0.005 to 0.3 carbon, 0 to 4 tungsten, 0 to 1 tantalum and balance nickel and incidental impurities.

Uma liga ultra supercritical da tubulação da caldeira caracterizada por um microstructure estabilizou-se e strengthened para 375 bar/700.degree. C. cozinhe, em por cento do peso, serviço e alloyed para resistir a corrosão do gás de carvão ash/flue por 200.000 horas que consistem em 10 a 24 cobalt, 22.6 a 30 cromo, 2.4 a 6 molibdênio, 0 a 9 ferro, 0.2 a 3.2 alumínio, 0.2 a 2.8 titânio, 0.1 a 2.5 niobium, 0 a 2 manganês, 0 a 1 silicones, 0.01 a 0.3 zirconium, 0.001 a 0.01 boro, 0.005 a 0.3 carbono, tungstênio 0 a 4, 0 a 1 niquelar do tantalum e do contrapeso e impurezas incidentais.