3 Inoculant Alloy Composition
3 Inoculant Alloy Composition
3 Inoculant Alloy Composition
Ferrosilicon alloys for use, as inoculants for cast irons must contain small amounts of one or more elements in order to obtain the required effects in the iron. Generally, inoculants may contain controlled amounts of several alloying elements in order to improve their effects but the most important elements in commercial inoculants are:
Primary elements Calcium Barium Strontium Aluminium Beneficial elements Zirconium Cerium (Rare Earths) Strontium Sulphur Oxygen
Strontium differs from the other elements in that it is only fully effective in the absence of calcium and aluminium, whereas the other alloys can benefit from being in combination. No FeSi-based inoculant will be effective without balanced additions of one or more of these elements. The figure below shows a schematic example of inoculation effect as a function of total reactive element content in the inoculant (i.e. Ca, Ba, Sr, etc.), and shows that optimum effect is obtained at concentrations above 0.5 per cent.
Inoculation effect (e.g. nodule count or chill reduction) as a function of total reactive element content in a ferrosilicon inoculant.
Copyright Elkem AS
Web www.foundry.elkem.com Org. no. NO 911 382 008 MVA Revision No. 2.5 16.02.2011
1. Contents of strontium, calcium or barium between 0.6 to 1.5 per cent normally give the required level of inoculation in cast irons under most foundry conditions. 2. When the strontium content or the sum of calcium plus barium content falls below about 0.5 per cent the inoculating effect will be significantly reduced and carbides or chill may occur. 3. Alloy contents above about 1.5 per cent may give improved inoculation under some conditions but may also give a greater tendency to produce slag or dross. 4. Grey irons with sulphur contents below about 0.05 per cent may only respond to certain specialised inoculants (e.g. strontium plus zirconium containing). 5. Inoculants alloyed with strontium are extremely effective for treating most grey irons but may be less effective in ductile irons containing high levels of rare earths as part of their nodularizing treatment. For more detailed information on inoculant composition please refer to Elkem Brochures: "Cast Iron Inoculation", Alinoc inoculant Barinoc inoculant Foundrisil inoculant Reseed inoculant SMZ inoculant Superseed inoculant Superseed Extra inoculant Ultraseed inoculant Zircinoc inoculant