PRODUCTION OF STEEL FOR USING AT LOW TEMPERATURE

• Main Authors: IKEDA TATSUO, AKUTAGAWA YOICHI, OSHIRO TAKEHIKO
• Format: Patent
• Language: English
• Published: 09.01.1988
• Subjects: ALLOYS; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; TREATMENT OF ALLOYS OR NON-FERROUS METALS

PURPOSE:To produce a steel for using at low temp. having excellent low temp. ductility by executing finish hot-rolling to the low C steel adding the specific composition of B at the specific accumulated rolling reduction ratio and rolling temp. and next controlling to cooling. CONSTITUTION:The steel composing of 0.03-0.15wt% C, 0.05-0.50% Si, <=0.50% Mn, <=0.015% P, <=0.015% S, 0.0005-0.0030% B and remaining part of Fe and inevitable impurities, is heated at <=Ac3 transformation point and <=1,100 deg.C. Next, the finish hot-rolling is executed at >=45% the accumulated rolling reduction ratio and the range of >=Ar3 point and <=850 deg.C of rolling temp. to the steel. In succession, it is cooled at 0.3-30 deg.C/sec average cooling speed. In the steel having the above composition, as necessity requires, it is further composed of one kind or more of among 0.05-0.20% Mo, 0.005-0.030% Ti, 0.005-0.050% Al. In this way, the steel for using at low temp. having fine crystal grains and below about -12 deg.C Charpy impact value transition temp. is obtd.