M aterial and technique of S i-M o heatresistant verm icular iron exhaust m anifold

摘要

S i-M o verm icular iron is an ideal m aterial for exhaust m anifold that w orks in high temperature and therm alcycle conditions because its properties oftherm alfatigue resistance and therm aldistortion resistance are significantly better than that of gray cast iron and nodular iron.This paper explains that the verm icularity of S i-M o verm icular iron is better to be controlled approxim ately to 50% for the applications of exhaust m anifold castings, and generalizes the successfulexperience ofverm icularizing technique thatuses sandw ich (pourover)process com bining w ith cored-w ire injection in trough process together,and uses rare earths-m agnesium -silicon as verm icularizing alloy in D isa high speed m olding line and autom atic plug rod airpressure pouring furnace. In addition, this paper also describes the m ethod to solve the shrinkage hole and porosity defects in the exhaustm anifold production.