| 摘要 |
PURPOSE:To satisfy the standard strength of shape steel without changing the material of steel, in the production of many kinds of shape steel, by controlling the cooling rate of the thin part in the process and after rolling. CONSTITUTION:The strength level of rolled steel is approximately decided by chemical componental value, pearlite ratio and ferrite grain size. The control of the rolling process for the purpose of the same is indispensable. At the time of producing shape steel having 12 to 40m flange thickness by a bloom having specified chemical components, the rolling of the bloom is started at 1100 to 1300 deg.C. The process in which rolling is executed by the recuperating stage between passes in reverse rolling is repeated one or more times, the rolling average temp. of the flange is regulated to <=950 deg.C and the total draft is regulated to >=20%. The outside face of the flange is cooled at 0.5 to 10 deg.C/sec cooling rate in accordance with the thickness of the flange. In this way, the carbon equivalent can be aggregated to two kinds of 0.21 to 0.25% and 0.29 to 0.37%. |
