| 摘要 |
<p>PURPOSE:To manufacture Cr-Mo steel having remarkable softening resistance in tempering with a little addition of Nb, by quenching the low carbon steel containing Si, Mn, P, S, Cr, Mo, Al, N, Sn, Sb, As and Nb, after said steel has been heated into specially determined temperature range for tempering. CONSTITUTION:The steel consisting of C; 0.08-0.17wt%, Si<=0.50wt%, P<= 0.010wt%, S<=0.010wt%, Cr; 1.80-3.50wt%, Mo; 0.80-1.20wt% acid-soluble Al<=0.025wt%, N; 0.0030-0.0120wt%, Sn<=0.010wt%, Sb<=0.010wt%. As<= 0.010wt% and Nb; 0.010-0.050wt%, and if necessary, at least either one of Cu<=0.20wt% or Ni<=0.30wt%, and a residue consisting substantially of Fe, is heat treated by the following method. That is, the steel is heated and quenched at about[580(%C)<0.5>+800] deg.C and below 1,300 deg.C, or the steel heated in said temperature range is hot-worked and then quenched from the temperature above Ar3 transformation point.</p> |
