| 摘要 |
PURPOSE:To produce steel products for structural purposes, etc., having the assigned quench hardness by setting the contents of C, Mn and Cr of the steel products having the prescribed compsn. in accordance with the relation between the distances from a hardening end and the Jominy hardness thereof. CONSTITUTION:The ingot of steel consisting, by weight %, of 0.13-0.26% C, 0.15-0.5% Si, 0.6-0.9% Mn, 0.85-1.20% Cr, 0.01-0.07% Al, 0.006-0.020% N, <=0.035% P, <=0.035% S, and the balance Fe and inevitable impurities is produced. The upper and lower limits of the content of C are controlled to the higher value of the values determined by formula I or formula II where the hardnesses at the distances 1.5mm, 5mm, 7mm, 9mm from the hardening end in the Jominy end hardening test are respectively designated as 1.5, 5, 7, 9 Hrc. The upper and lower limits of 1.6Mn(%)+Cr(%) are controlled to the range where the values determined by formulas III, IV, V overlap. The steel products with which the hardenability of the prescribed hardness is assured are produced by the above-mentioned method.
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