| 摘要 |
PURPOSE:To improve the surface roughening resistance of a work roll for cold rolling, by heat treatment under specific conditions of the work roll made of high carbon steel contg. Cr, or Mo and V in addition, in order to uniform the distribution of precipitated carbide. CONSTITUTION:Steel material contg. 0.6-1.0% C, 2.0-5.0% Cr, in addition small quantities of Mo, V is hot forged to manufacture a work roll for cold rolling. The work roll is heated at an austenitizing temp. 950-1,150 deg.C as as to form complete solid solution of carbide, then cooled rapidly in order to inhibit the pearlite transformation and to prevent the crystallization of coarse carbide. Transformation is performed at a temp. not higher than 550 deg.C in order to obtain uniformly distributed fine carbide. Then the work roll is tempered at a temp. 600-750 deg.C so as to crystallize hard carbide such as fine carbide of Cr or Mo uniformly distributed in dentritic and interdenstritic part of dentrite structure by tempering at a temp. 600- 750 deg.C. Hereby the hardness of the surface of the roll is uniformly increased, the surface roughening resistance is improved, and the life time of the roll is extended. |
