Cast iron & Ductile iron foundry practice

CAST IRON METALLURGY

Cast Iron:

Classification of Cast Iron:

Carbon Equivalent:

DUCTILE IRON (SPHEROIDAL GRAPHITE IRON):

Elements such as copper or tin may be added toincrease tensile and yield strength whilesimultaneously reducing ductility.Improved corrosion resistance can be achieved byreplacing 15% to 30% of the iron in the alloy withvarying amounts of nickel, copper, or chromium

desulphurization methods:

Fusite methodFlour spur(CaF2) methodCalcium carbide methodDesulfurization of steel by injection of active agents

Magnesium treatment:

In order to prevent formation of low-melting iron sulphide manganese (Mn) is added to steel to a content not less than 0.2%.

(FeS) + [Mn] = (MnS) + Fe The melting temperature of manganese sulphide is relatively high - about 2930°F (1610°C) therefore the steels containing manganese may be deformed in hot state

MnS inclusions are: Brittle (less ductile than steel);They may have sharp edges;They are located between the steel grains.

Graphite Morphology: