| 摘要 |
Provided are a surface layer material of a hot rolling mill roll and a hot rolling mill composite roll having high wear resistance, heat shock resistance, and surface deterioration resistance at the same time. The surface layer material has a chemical composition containing, by mass%, C: 2.4% or more and 3.5% or less, Si: 1.2% or more and 2.4% or less, Mn: 0.2% or more and 2.0% or less, Cr: 0.8% or more and 2.1% or less, Mo: 0.3% or more and 1.1% or less, Ni: 3.0% or more and 6.0% or less, V: 1.0% or more and 2.2% or less, Nb: 0.1% or more and 0.5% or less, REM: 0.0005% or more and 0.1% or less, Al: 0.003% or more and 0.05% or less, and the balance being Fe and inevitable impurities, in which the contents of C, Cr, V, Nb, REM, and A1 satisfy the relationships Cr+0.2 < C-(0.24xV+O.l3xNb) < 3.0 and 0.01 < REM/Al 5 3.2 (where C, Cr, V, Nb, REM, and A1 respectively represent the contents (mass%) of corresponding chemical elements) . |
