Simple understanding of QT450-10 and ferritic ductile iron

- Oct 19, 2018 -

Ductile iron, in its specific type, is QT450-10 ductile iron and ferritic ductile iron. Therefore, it is necessary to familiarize and understand to correctly understand the two specific types of ductile iron, knowing that they are specifically What and what basic knowledge and content are included.


One of the types of ductile iron: QT450-10 ductile iron

QT450-10 ductile iron, which is a ferritic ductile iron with high toughness and ductility. In the low temperature state, its toughness will change to brittleness, but the low temperature impact performance is better, and it has certain resistance to temperature and corrosion. In terms of use, this kind of ductile iron is widely used in agricultural machinery to make such parts as plows, ploughs, differential cases, etc., and it can be used in general machinery to make valve bodies, high and low pressure cylinders and the like. Device.


The chemical composition and proportion of QT450-10 ductile iron are:

Carbon C: 3.7-4%

Silicon Si: 2.15 - 2.93%

Manganese Mn: 0.46-0.66%

Sulfur S: 0.01—0.016%

Phosphorus P: 0.027-0.035%

Magnesium Mg: 0.027-0.05%

Rare earth Re: 0.026-0.043%

Carbon equivalent: 4.3-4.6%


The mechanical properties of QT450-10 ductile iron are:

Tensile strength: ≥450MPa

Conditional yield strength: ≥310MPa

Elongation: ≥10%

Hardness: 160-210HB


The metallographic structure of QT450-10 ductile iron, which is:

Heat treatment specification: as-cast or normalized

Metallographic structure: in the as-cast state, it is graphite + ferrite (matrix structure) + pearlite; in normalizing, it is graphite + more pearlite + ferrite, which can obtain higher comprehensive mechanical properties. In particular, the plasticity and toughness are improved.


No. 2 of ductile iron: ferritic ductile iron

Ferritic ductile iron, which is a ductile iron with a matrix of ferrite, referred to as ductile iron, has a certain strength, good impact toughness and plasticity, and can be obtained by annealing in an as-cast state.


In ferritic ductile iron, each element has a certain influence, which is:

Carbon: Conducive to graphitization and spheroidization to ensure the toughness of the material.

Silicon: It can promote graphitization and help to improve the toughness of materials. The final silicon content is generally controlled below 2.7%.

Manganese: It can hinder the decomposition of cementite and pearlite, and its content should be controlled below 0.4%.

Phosphorus: A brittle phase is formed in cast iron. However, it is possible to avoid the generation of phosphorus eutectic by metal casting into a hemp port and annealing at high temperature.

Sulfur: To control its content, because its content is too high, it will make the spheroidization unstable and produce excessive sulfide inclusions, which will affect the toughness of the material.