| 摘要 |
PURPOSE:To manufacture steel stock having small deformation resistance at cold working time, by heating and hot rolling steel slab contg. a specified quantity of C while specifying the final finishing temp., and cooling, then providing a specified metallographic structure to prevented deteriorations of tensile strength and hardness. CONSTITUTION:Steel slab contg. 0.30-0.60% C is heated to about 900-1,200 deg.C, hot rolled and the final finishing temp. is regulated to 650-800 deg.C. In this way, metallographic structure after cooling is composed of fine ferrite and pearlite of >=No.10 grain size number, further tensile strength and hardness are not decreased in as hot rolled state and deformation resistance during cold working is reduced. It is desirable to control <=0.30% Si, <=0.03-2.00% Mn, <=1.20% Cr, <=0.20% Mo, <=1.00% Ni, <=0.030% P and S, <=0.020-0.100% Al, 0.0020-0.0100% N in steel component.
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