CORROSION RESISTING STEEL FOR INTERNAL CYLINDER FOR COAL- FIRED THERMAL POWER PLANT SMOKESTACK, EXCELLENT IN CORROSION RESISTANCE IN WELD ZONE, AND SMOKESTACK

摘要

PROBLEM TO BE SOLVED: To produce a high alloy steel excellent in corrosion resistance in a weld zone under a coal-fired thermal power plant smokestack environment and a high efficiency smokestack using the same. SOLUTION: The high alloy steel is composed of an alloy which has a composition consisting of, by weight, <=0.02% C, 21-27% Cr, 18-27% Ni, 0.1-0.3% N, 0.3-2.0% Cu, further at least either of Mo and W in amounts within the range satisfying Mo+1/2×W=3 to 5%, and the balance essentially Fe and satisfying the inequality Ni-0.6Cr+1.5(Mo+1/2×W)+7.5Cu+122N>=45.