INVESTIGATION ON CAST IRON HAVING REFINED GRAPHITE PRODUCED BY MELTING CAST IRON COVERING WITH SLAG CONTAINING TiO₂ (IX)

Investigation on the Net Structure and the Estimation of Micro-Hardness of S-H Cast Iron

Abstract

The fracture surface as well as the polished surface of S-H cast iron shows a net structure having a boundary line of light gray color. The microstructure proved that the boundary-line portion was a group of austenite dendrite and that the mesh of net (meshy portion) was consisted of eutectic graphite structure.
Both the micro-hardnesses of boundary-line and meshy portions were estimated. The results proved that the hardness of boundary-line portion was about 1.5-2.7 times of meshy portion.
The authors presumed that one of the major reasons of the greater wear-resistance of S-H cast iron was based upon the following characteristics:
1. The existence of a unique net structure of S-H cast iron.
2. The presence of a boundary-line portion of greater hardness in the matrix of eutectic graphite structure of lower hardness.
3. The fine and uniform distribution of fine TiC particles in S-H cast iron casting.