The production of high-density hollow cast-iron bars by vertically continuous casting

Hollow cast-iron bars with an outer diameter of 60–300 mm, a wall thickness of 7–40 mm and a length of 10 m or longer were produced massively by vertically continuous casting. The whole casting processes were analogous to the casting processes of solid bars by horizontal continuous casting. The metallographic microstructure, the distribution of chemical composition along their radius direction and the mechanical properties of the hollow bars were investigated. The results show that the hollow cast-iron bars are compact and few shrinkage cavities and shrinkage porosities exist in them. Their graphite grains or their eutectic colonies are very fine and their mechanical properties are superior to that of bars produced by sand casting. Their chemical composition is distributed uniformly along their radius direction and no segregation was observed.