Difference Between Ductile Iron And Gray Cast Iron

The core difference between ductile iron and gray cast iron lies in the different graphite morphology, which leads to significant differences in mechanical properties and application scenarios. Graphite in gray cast iron is flake like, while graphite in ductile iron is spherical. ‌‌

Graphite morphology: Grey cast iron carbon exists in the form of flake graphite, which is prone to stress concentration at the tip and severely fractures the matrix; Ductile iron forms graphite into spherical shapes by adding spheroidizing agents such as magnesium and rare earth elements, with minimal effect on matrix fragmentation.

Mechanical properties: Grey cast iron has low strength and plasticity, high brittleness, but excellent shock absorption, wear resistance, and casting performance; Ductile iron has high strength and good toughness, with a tensile strength of up to 400-600 MPa. Its comprehensive performance is close to that of steel and can withstand complex loads.

Process characteristics: Grey cast iron has good machinability and generally does not undergo heat treatment strengthening; Ductile iron can significantly improve its wear resistance and strength through heat treatment, such as isothermal quenching. ‌‌‌