多合金系白鋳鉄の機械的性質並びに熱間摩耗特性に及ぼす炭素及びニッケルの影響

抄録

  Multi-component white cast irons containing Cr, Mo, W and V have been widely popularized as roll materials for hot rolling mills because of their excellent wear resistance. In this research, effects of C and Ni contents on mechanical properties and hot wear resistance were investigated using Fe-5%Cr-5%Mo-5%V-5%W-Ni-C (mass%) cast alloys. MC and M₂C carbides crystalized in all specimens, and M₇C₃ carbides appeared in high C and high Ni cast irons. Martensitic matrix was obtained in some specimens with C=1.5mass% and Ni less than 5mass%, and those with 2.0～3.0mass%C and Ni less than 2.5mass%. The addition of 1mass%Ni to cast irons with around 2mass%C improved the hardenability. The increase in Co content led to a transformation of soft pearlite. Martensitic matrix showed over 600HV in micro-hardness, and the variation of macro-hardness was closely related to that of micro-hardness. Tensile strength and compressive 0.2% proof strength were high in cast irons with high hardness. 1.5mass%C-0mass%Ni cast iron showed minimum wear loss or highest wear resistance, and 1.5mass%C-10mass%Ni cast iron showed the largest fracture toughness.