Inoculation of Cast Iron
FeSi70 is added to molten iron just before pouring as an inoculant to promote graphite nucleation and refine graphite morphology. Silicon in FeSi70 provides nucleation sites for graphite, encouraging the formation of fine flake graphite in gray iron or spherical graphite in ductile iron. This reduces chill depth, prevents the formation of harmful carbides, and improves machinability and tensile strength. For heavy-duty components such as brake discs, cylinder liners, and large gear housings, the result is enhanced toughness and resistance to thermal fatigue.
Alloying for Solid Solution Strengthening
Silicon is a strong ferrite stabilizer and strengthens the iron matrix by solid solution strengthening. In heavy-duty castings subject to high loads or abrasive wear, silicon increases hardness while retaining adequate ductility, and FeSi70 allows precise silicon adjustment without excessively raising carbon content. This improves load-bearing capacity and abrasion resistance in mill rolls, crusher jaws, and hydraulic pump casings.
Control of Eutectic Cell Count
Proper inoculation with FeSi70 increases the number of eutectic cells, leading to a finer microstructure throughout the casting section. This is especially important in heavy-section castings where slow cooling can cause coarse graphite and reduced properties, and it minimizes property variation between the casting surface and center for large mining and construction machinery components.
Prevention of White Iron Formation
In thick-walled heavy-duty castings, slow cooling rates can lead to white iron zones rich in carbides, which are difficult to machine and prone to cracking. FeSi70 inoculation lowers the carbon equivalent locally, suppressing carbide formation and encouraging graphite precipitation, reducing casting defects and machining problems in large engine blocks and heavy press components.
Fluidity Improvement and Pearlite Stabilization
Silicon lowers the melting point slightly and improves fluidity, allowing molten iron to fill complex mold cavities and thin sections without cold shuts or misruns, ensuring sound castings for pump housings, valve bodies, and turbine casings. Silicon also stabilizes pearlite and retards its decomposition during slow cooling, so a predominantly pearlitic matrix improves strength and wear resistance in service, extending the life of track rollers and crushing equipment parts.
Frequently Asked Questions
Q: What is FeSi70 used for in cast iron?
A: Inoculation, alloying, eutectic refinement, carbide suppression, fluidity improvement, and pearlite stabilization.
Q: How does inoculation improve cast iron?
A: It provides graphite nucleation sites, producing fine, uniform graphite with reduced chill.
Q: What is the silicon content of FeSi70?
A: About 70 percent, typically within the 68 to 72 percent range.
Q: Why is white iron formation harmful?
A: Carbide-rich zones are brittle and difficult to machine, causing defects and machining problems.
Q: How does FeSi70 improve fluidity?
A: Silicon lowers the melting point, helping molten metal fill complex molds completely.
Q: What is the effect on pearlite?
A: Silicon stabilizes pearlite, improving strength and wear resistance in service.
For FeSi70 quotations with your required grade and size, contact our sales team.