一方向性凝固した白鋳鉄の凝固組織と凝固条件との関係

抄録

  This paper is one of the serial investingations on the structure of white cast iron. This paper focuses on the relationship between the structure and the solidification conditions of eutectic and neary eutectic Fe-C-3.0%Cr and Fe-C-3.0%Cr-3.0%Mo alloy solidified unidirectionally under controlled conditions. Round castings of the alloys, 8.5mm diameter and 30mm length were melted and solidified unidirectionally by downward motion at constant speeds in a vertical furnace. The solidification rates were controlld within the range of 101.3 to 3.0 mm/hr.
  As the solidification rate decreased, the ledeburitic eutectic structure of F-C-Cr alloy, which were almost rod-like, became coarse and chrysanthemum-shaped. This structure change was also observed by adding Ni and V to this alloy. The formation of chrysanthemum-shaped eutectic structue was also affected by the temperature gradient in the liquid ahead of the solid-liquid interface. As for Fe-C-Cr-Mo alloy, the change into chrysanthemum-shaped eutectic structure was hardly observed. The chrysanthemum-shaped eutectic structure was closely related to the shape of the primary austenite.