STEEL PLATE WITH EXCELLENT DURABILITY FOR BAND-SHAPED DIE-CUTTING BLADE, AND BAND-SHAPED DIE-CUTTING BLADE

摘要

A steel plate for band-shaped die-cutting blades which has excellent bendability and durability, the steel plate comprising: a base part located beyond a depth of 200 µm from each surface of the steel plate, the base part having a chemical composition that contains 0.40-0.80 mass% C and 0.10-0.50 mass% Nb and having a metallographic structure which comprises bainite or tempered martensite and in which a spherical carbide constituted of cementite is present in the bainite or tempered martensite in an amount of 1.0 vol.% or more and a Nb-containing carbide having an equivalent-circle diameter of 0.5 µm or larger is present at a density of 10.0 or more grains per 900 µm2, the base part having a hardness regulated to 300-450 HV; and surface layer parts which each include a decarburized surface layer that is constituted only of a ferrite phase and has a thickness of 5 µm or larger and in which the 15-µm-thick surface layer regions each contain a Nb-containing carbide with an equivalent-circle diameter of 0.5 µm or larger at a density of 0-5.0 grains per 900 µm2.