| 摘要 |
PURPOSE:To obtain high carbon steel rod having high yield stress and superior straightness, by applying pearlitic transformation and controlled cooling to steel rod under specified conditions, and aging it forcedly to provide a specified tensile stress thereto, at uniform rate cooling of hot rolled steel rod. CONSTITUTION:When steel rod after hot rolling is cooled by uniform rate, if denoting critical temp. in contact with pearlitic transformation starting line of CCT curve of the steel rod as TC, pearlitic transformation is started in TC-TC+40 deg.C range. Further, the rod is cooled regulatedly to suppress max. temp. during transformation to TC+80 deg.C up to room temp. to carry out controlled aging. Or the rod is aged forcedly in the midway of cooling after pearlitic transformation, and tensile stress less than rupture stress and higher than yield stress is applied to the steel rod during the forced aging or cooling up to room temp. after end of forced aging. In this way, high carbon steel rod having superior straightness and high yield stress is obtd. stably.
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