| 摘要 |
PURPOSE:To produce a steel having excellent hydrogen attack resistance characteristic by processing Mo or Mo-Cr-contained low alloy steel in the austenitic range at much reduction and holding at tempering temp. of <=Ar3 transformation point after natural-cooling. CONSTITUTION:The Mo-contained low alloy steel or Cr-Mo-contained low alloy steel is processed in the austenitic range of comparatively low temp. such as <=1,250 deg.C and desirably <=1,000 deg.C, and at >=50% reduction ratio by rolling, etc. The above steel is suitable to contain 0.05-0.35wt% C, 0.01-1.0% Si, 0.1-1.5% Mn, 0.01-2.0% Mo, and if necessary, 0.01-4.9% Cr, <=0.05% Al and/or <=0.05% Ti and further if necessary, one kind or more among <=0.5% V, <=0.2% Nb, <=0.003% B. After completing the process at >=Ar3 transformation point, by the natural cooling or controlling velocity, it is tempered at <=Ar1 transformation point and held at it is for a specific time. In this way, a thermochemically stable carbide is formed in large quantity and steel having excellent hydrogen attack resistance characteristic is obtd.
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