Effect of dendrite liquation on the pearlitic-ferritic structure of gray cast iron

Abstract

1. Dendrite inhomogeneity of the pearlitic structure of gray cast iron, developed during secondary heating of castings or slow cooling in the subcritical temperature range, has a thermodynamic character and it leads to a marked reduction in cast iron strength. 2. The stiffest thin-walled parts of a cast article governing its structural strength are characterized by the lowest thermal stability for the pearlite structure and they start to ferritize noticeably at 600°C, which leads to a reduction in their initial strength by 20–25%. 3. In order to improve the strength of iron castings they should be heat treated, including high-temperature austenitizing and a stepped cooling schedule.