Effect of heating temperature on microstructure and properties of magnesium cast iron

Abstract

1. Heating at temperatures below Ac1S leads to spheroidization and intensive dissociation of cementite in pearlite with formation of a structure that is mainly ferritic, which promotes some equalization of the microdistribution of silicon. 2. Heating in the intercritical range leads to formation of a special type of microstructure in the metallic matrix in which the austenite formed in ferrite is lamellar or acicular. With rapid cooling this type of structure is fixed at room temperature. Various decomposition products may be present in prior austenite sections. 3. The formation of the special microstructure in the intercritical range is accompanied by the formation of exceedingly fine silicon in the metallic matrix and thus a reduction of its embrittling effect. 4. Heat treatment in the intercritical range ensures a good combination of mechanical properties in magnesium cast iron.