PRODUCTION OF HIGH-CARBON STEEL OR HIGH-CARBON ALLOY STEEL SHEET HAVING FINE SPHEROIDAL CARBIDE

摘要

PURPOSE:To save energy consumption and improve productivity by subjecting a high-carbon steel to hot rolling at =Ar3, to cooling at specific cooling velocity, to coiling at specific temp., to specific cold working, and then to heating and holding at specific temp. CONSTITUTION:A high-carbon steel or high-carbon alloy steel is hot-rolled in a temp. region of =Ar3, cooled at =30 deg.C/S cooling rate, and coiled in the temp. range between 500 deg.C and Ms. Subsequently, the hot rolled sheet is cold- rolled at =10% draft, and the resulting sheet is heated up to a temp. between the recrystallization temp. and the A1 point and held at the above temp. for 30-600sec, or, after the above hot rolling, the hot rolled sheet is coiled in a temp. range of (Ms+Mf)/2 while being cooled at =30 deg.C/S cooling rate and is then cold-rolled at =10% draft, followed by holding in a similar manner as above. By this method, spheroidizing treatment can be carried out in a short time.