The chemical composition of ductile iron mainly includes the five common elements of carbon, silicon, manganese, sulfur and phosphorus. For some castings with special requirements on organization and performance, a small amount of alloying elements are also included. Unlike ordinary gray cast iron, ductile iron must also contain trace amounts of residual spheroidal elements in order to ensure graphite spheroidization. We manufacture a wide range of castings for Japanese and European trucks, such as spring bracket, spring shackle, spring pin and spring bushing.
1, Carbon and carbon equivalent selection principle: carbon is the basic element of ductile iron, high carbon helps graphitization. However, high carbon content will cause graphite floating. Therefore, the upper limit of carbon equivalent in ductile iron is based on the principle of no graphite floating.
2, Silicon selection principle: Silicon is a strong graphitizing element. In ductile iron, silicon can not only effectively reduce the tendency of white mouth and increase the amount of ferrite, but also has the role of refining eutectic clusters and improving the roundness of graphite spheres.
3, Manganese selection principle: As the sulfur content in ductile iron is already very low, do not need too much manganese to neutralize sulfur, the role of manganese in ductile iron is mainly in increasing the stability of pearlite.
4, Phosphorus selection principles: phosphorus is a harmful element, it is extremely low solubility in cast iron. In general, the lower the content of phosphorus in ductile iron, the better.
5, Sulfur selection principle: Sulfur is an anti-spherical element, it has a strong affinity with magnesium, rare earth and other spheroidal elements, the presence of sulfur will consume a lot of spheroidal elements in the ferrofluid, the formation of magnesium and rare earth sulfides, causing slag, porosity and other casting defects.
6, Spheroidal elements selection principle: in the premise of ensuring the spheroidal qualified, the residual amount of magnesium and rare earth should be as low as possible. Magnesium and rare earth residues are too high, will increase the tendency of the white mouth of the iron liquid, and will affect the mechanical properties of the castings due to their segregation at the grain boundaries.
Post time: Jul-04-2023
