THERMAL FRACTURE ENDURANCE OF CAST IRONS WITH APPLICATION STUDY OF PIG-IRON INGOT MOLDS

Pig iron ingot molds manufactured with flake, compacted graphite cast iron, and spheroidal graphite cast iron were installed on a pig iron casting machine and subjected to thermal cycling for studying thermal fracture endurance of the three cast irons. The effects of graphite morphology on the fracture mechanism were analyzed by examining the fracture patterns, microstructures, and microcracks in the failed molds. The determining factors of thermal fracture endurance were elucidated with thermal fracture resistance indices. Compacted graphite cast iron exhibited better thermal fracture endurance than flake and spheroidal graphite cast irons because of its higher strength-to-thermal stress ratio.