| 摘要 |
PROBLEM TO BE SOLVED: To provide a roll outer layer material for hot rolling and a composite roll for the hot rolling, superior in fatigue resistance of a roll surface later, and hardly causing a fatigue flaw and chipping-off.SOLUTION: The roll outer layer material is provided which contains fine carbide having an equivalent circle diameter of 3-30 μm in an amount of 500-2,500 pieces/mm, and coarse carbide having an equivalent circle diameter of 50 μm or more being present in an amount of 20 pieces/mmor less. The roll outer layer material is preferably a cast iron-based roll outer material which is composed of a composition containing (by mass%) C:2.4-2.9%, Si:0.2-1.0%, Mn:0.2-1.0%, Cr:4.0-7.5%, Mo:4.0-6.5%, V:5.3-7.0%, Nb:0.5-3.0%, and satisfying 1.5≤(Cr+Mo)/V≤2.4 (here, Cr, Mo, V: the content (mass%) of respective elements), and further preferably containing one kind or more of Al:0.001-0.05% or REM:0.001-0.03%, and the balance comprising Fe and an inevitable impurity. The composite roll for the hot rolling is also provided which has the outer layer material. |
