| 摘要 |
PURPOSE: To produce a ferritic heat resistant steel excellent in HAZ softening resistance by specifying a composition consisting of C, Si, Mn, Cr, Mo, W, V, Nb, N, Ti, Zr, and Fe and controlling the composition of a carbide. CONSTITUTION: This steel has a composition which contains, by weight, 0.01-0.30% C, 0.02-0.80% Si, 0.20-1.50% Mn, 0.50-5.00% Cr, 0.01-1.50% Mo, 0.01-3.50% W, 0.02-1.00% V, 0.01-0.50% Nb, and 0.001-0.06% N and contains 0.001-0.8% Ti and 0.001-0.8% Zr independently or in combination and further contains, if necessary, 0.2-5.0% of Co and/or Ni and in which the contents of P, S, and O are limited to <=0.030%, <=0.010%, and <=0.020%, respectively. Further, in this steel, Ti+Zr in the metallic component M in an M23 C6 type carbide is regulated to 5-65. This steel can be obtained by performing the addition of Ti and Zr during 10min just before tapping, subjecting the steel to casting and rolling or forging, temporarily stopping the cooling, after solid solution heat treatment, at 800-930 deg.C, and performing holding for 5-60min. |
