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

Conclusions

• 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.