| 摘要 |
The steel castings for low temperatue are manufactured by fuse- mixing Fe with 0.08-0.12 wt.% C, 0.2-0.4 wt.% Si, 1.0-1.6 wt.% Mn, 0.04 wt.% or less P and S, 0.1 wt.% or less Al, 0.01 wt.% or less Ca, 0.01-0.20 wt.% Nb, 0.2-2.0 wt.% Ni and below 0.0001 wt.% B to make 0.42 carbon equivalent in an air or vacuum atmosphere, heating the solidified steel casting at the rate of 45-50 deg.C/ hr to 920-950 deg.C, one-normalizing or double- normalizing, tempering at 610-630 deg.C again, and cooling in an air atmosphere. The castings has an excellent strength and toughness.
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