This material specification covers castings made of high temperature resistant iron as used in automotive and allied industries, including the mechanical properties from separately cast Y-block test samples and compositional requirements in the product castings. Any specific requirements for the whole or a critical section of a casting shall be identified on the engineering drawing.
Material Description. Grades of nodular iron and one (1) of compacted graphite iron are addressed. High temperature nodular iron is alloyed with additional silicon, molybdenum and sometimes other elements to provide improved properties at elevated temperatures. Nodular iron is produced by treating molten iron of appropriate base metal composition with magnesium. The higher silicon and molybdenum level gives the iron better resistance to scaling and better dimensional stability while improving resistance to creep and elevated temperature strength.
Compacted graphite iron production is similar to nodular iron with the addition of rare earth elements, but it also requires another alloying element such as titanium to minimize the formation of spheroidal graphite. The graphite structure and resulting properties of the iron are an intermediate between gray and ductile irons.
Symbols. Not applicable.
Applicability. High temperature resistant cast iron is used for those applications which require a higher resistance to heat, resistance to scaling and dimensional stability at elevated temperatures. Exhaust manifolds and turbo charger housings are the typical applications for this iron.