A high-chromium ferritic steel excellent in high-temperature ductility and strength

摘要

A high Cr ferritic steel of this invention is excellent in ductility and strength at elevated temperatures and consists of by weight, 0.02 to 0.15% C, up to 0.5 Si, 0.1 to 1.5% Mn, up to 0.025% P, up to 0.015% S, up to 0.005% O, 8 to 14% Cr, 0.1 to 0.3% V, 0.01 to 0.2% Nb, 0.01 to 0.1% N, up to 0.05% Al, 0.001 to 0.02% B, 0.05 to 3.0% Cu, 1.0 to 5.0% Co, one or both of 0.01 to 1.2% Mo and 0.8 to 3.5% W, and the balance being Fe and incidental impurities, wherein the relationship between the Cu and Co content is defined so as to satisfy the following formula (1). $The\; steel\; may\; further\; contain\; 0.1\; to\; 1.5\%\; Ni\; by\; weight,\; wherein\; the\; proportion\; of\; Ni,\; Cu\; and\; Co\; content\; is\; defined\; so\; as\; to\; satisfy\; the\; following\; formula\; (2).$ If\; Cu,\; Co\; and\; optionally\; Ni\; are\; contained\; in\; the\; steel\; in\; well-balanced\; proportions,\; the\; high\; creep\; rupture\; ductility\; and\; strength\; of\; the\; steel\; can\; be\; sustained\; at\; high\; temperatures\; and\; for\; long\; periods\; of\; time.\mathop{\mathrm{image}}$$