What is the function of barium silicate inoculant in cast iron?
Ingestant is widely used in the cast iron industry, but what role does it play in cast iron? Let's take a look at it in detail.
Definition of inoculants:
Incubation treatment refers to adding a small amount of other substances to the liquid metal in the solidification process to promote nucleation, inhibit growth and achieve the purpose of refining grains. Customarily, adding additives to cast iron is called inoculation treatment; Adding additives to nonferrous alloys is called metamorphism. In essence, inoculation mainly affects nucleation and promotes grain dissociation. However, metamorphism changes the growth mechanism of crystals (inhibiting growth), thus affecting the morphology of crystals.
Role of inoculant:
The mechanical properties of gray cast iron depend on its microstructure to a great extent. Gray cast iron without inoculation treatment has unstable microstructure, poor mechanical properties and white holes in the thin wall of the casting. In order to ensure the consistency of casting quality, inoculation treatment is essential [1].
The amount of inoculant used in the inoculation treatment of cast iron has little effect on the chemical composition of cast iron, but great effect on its microstructure, so it can improve the mechanical properties of gray cast iron, and also has obvious influence on its physical properties. Good inoculation has the following effects:
Eliminate or reduce white mouth tendency;
Avoid supercooling structure;
Reduce the sensitivity of the wall thickness of cast iron, so that the difference of the microstructure of the thin and thick section of the casting is small, and the hardness difference is small.
◆ It is beneficial to nucleation of eutectic group and increase the number of eutectic group;
◆ The graphite form in cast iron is mainly fine and uniform distribution of A-type graphite, thus improving the mechanical properties of cast iron.
The fluidity of well-inoculated cast iron is better, the shrinkage of the casting is reduced, the workability is improved and the residual stress is reduced.
Method of use of inoculant
1, inverted inoculation: the inoculant will be added to the bag, and then poured into the molten iron, make it evenly melted, can be poured.
2. The amount added is about 1.0-1.8% by weight of liquid iron.
