Foundries add ferrosilicon inoculants to iron melts before casting to improve cast iron strength and structure. The recently updated Indian Standard IS 1110:2026 (Sixth Revision) defines and specifies inoculants, making BIS certification important for foundry inoculant suppliers.
The current Indian Standard for them is IS 1110:2026 (Ferrosilicon: Specification, Sixth Revision). The Bureau of Indian Standards published it in October 2026. It was first published in 1957 and revised in 1964, 1981, 1990, and 2023. This revision includes definitions of the inoculants and their grades.
What Is a Ferrosilicon Inoculant and ISI Mark?
The standard also refers to this product as an inoculant. Manufacturers add inoculants to the iron melt before casting to control the solidification process. They help to provide more nucleating sites and minimise undercooling. The ISI Mark is a certification mark issued by the Bureau of Indian Standards (BIS), indicating that a product conforms to the applicable Indian Standard and meets specified quality requirements under a valid BIS licence.
- Base alloy: A master alloy based on ferrosilicon, containing 45.0%- 80.0% silicon by weight.
- Elements added: Special elements (Ba, Sr, Zr, Ce, Ca, Al and Mn) are deliberately added, mostly within the range of 2% to 10%.
- Use: Metal treatment in ferrous metallurgy.
- Manufacture: Produced by induction or reduction melting, with alloying done either in the furnace or in the ladle after tapping.
- Function: Inoculants are added to iron melts before casting to control solidification. They provide more nucleating sites, helping avoid undercooling.
Alloyed Ferrosilicon Inoculant Grades Under IS 1110:2026
The standard covers 10 grades of alloyed ferrosilicon (Table 2). All are designated as per IS 2085.
Table 2: Alloyed ferrosilicon (inoculant) grades, composition in %
|
Grade |
Si |
Ca |
Ba |
Sr |
Zr |
Ce |
Mn |
Al |
|
FeSi47Ba60Al15 |
45–50 |
2.5 |
6.0 |
0.5–1.0 |
– |
– |
– |
1.5 |
|
FeSi65Zr60Mn60Al60 |
60–70 |
2.5 |
3.0 |
– |
6.0 |
– |
6.0 |
6.0 |
|
FeSi75Sr10Zr20Al15 |
70–80 |
2.5 |
3.0 |
0.5–2.0 |
1.0–3.0 |
2.5 |
2.0 |
1.5 |
|
FeSi75Al40 |
70–80 |
2.0 |
– |
– |
– |
– |
– |
3.0–5.0 |
|
FeSi65Zr40Al40 |
60–70 |
2.0 |
– |
– |
3.0–5.0 |
– |
– |
3.0–5.0 |
|
FeSi60Ca200Al30 |
55–65 |
20.0 |
3.0 |
2.0 |
3.0 |
2.0 |
2.0 |
3.0 |
|
FeSi45Ba350Al50 |
40–50 |
8.0 |
35.0 |
– |
4.0 |
– |
4.0 |
5.0 |
|
FeSi70Zr150Mn50Al20 |
65–75 |
5.0 |
– |
– |
15.0 |
– |
5.0 |
2.0 |
|
FeSi57Ca300Al20 |
52–62 |
5.0–30.0 |
3.0 |
– |
3.0 |
2.0 |
5.0 |
2.0 |
|
FeSi67Ca25Zr50Al50 |
62–72 |
0.5–2.5 |
4.0 |
– |
5.0 |
2.0 |
5.0 |
5.0 |
All values are maximum values except where stated otherwise. Iron is the balance. The standard also provides for the following:
Carbon (0.30% max), phosphorus (0.05% max), and sulfur (0.05% max) are the typical residual contents. These should be tested and reported.
Residual titanium (0.40% max) and boron (0.02% max) above these limits must be agreed between supplier and purchaser. The purchaser may request a certificate of analysis at an agreed frequency.
Testing and Quality Requirements for Ferrosilicon Inoculants
The test verifies the composition of chemicals, size of particles, and absence of foreign substances in the ferrosilicon inoculants, as per the relevant standards of IS 1110:2023
Check details of BIS FMCS Certification for foreign manufacturers
Chemical analysis: Composition shall be based upon the relevant portions of IS 1559 or some other reliable instrumental/chemical test procedure. If there is a difference of opinion, IS 1559 is the referee procedure. The relevant procedures cover silicon, Carbon, Sulphur, Phosphorus, Aluminium, Calcium, and Manganese. Annex A does not have any IS 1559 procedure for Ba, Sr, Zr, or Ce. In cases where referee procedures are not specified in IS 1559, they shall be agreed upon by the purchaser and the manufacturer.
Constitution of consignment: A consignment is constituted by one of the following methods:
- Tapped lot: One melt, or one part of a continuous tap.
- Graded lot: Several melts (or parts of continuous taps) of one ferrosilicon designation. The ferrosilicon content of these melts must not differ by more than 3%.
- Blended lot: Several melts (or parts of continuous taps) of one ferrosilicon designation, crushed to a particle size below 50 mm and thoroughly mixed.
Size: Available as lumps or as crushed and screened particles; the agreed size limits apply. The tolerances are oversize 10% maximum and undersize 15% maximum.
- No particle should exceed 1.15 times the maximum size in any two or three directions.
- 3.15 mm size fraction must not exceed 5%; if it does, the supplier and the purchaser must agree on the way forward.
Determine the size in accordance with IS 1607 and IS 15765, using test sieves as per IS 460.
- Extraneous materials: The material should be relatively free of slag and nonmetallic inclusions.
- Sampling: For chemical analysis, IS 1472; for size, IS 15765.
Ordering, Packing and Marking Requirements Under IS 1110:2026
The requirements for purchase, packing, and marking under IS 1110:2026 specify procurement, packing, marking, and the BIS certification mark for ferrosilicon.
- Order: The buyer specifies the consignment make-up, material name, grade, size range, quantity, residual-elements test report, analysis report, and packing details. Supply conditions are generally as per IS 1387.
- Packing: 20 kg, 25 kg, 50 kg, 500 kg, 1 tonne, or 1.5 tonne bags, packed in HDPE/PP woven bags complying with IS 11652 or other packaging agreed with the buyer. Bags should be in good condition when inspected.
- Marking: Manufacturer, grade, cast/lot and size marking, quantity, manufacturing date, and shelf life if applicable. Conforming products can be certified under the Bureau of Indian Standards Act, 2016 for BIS ISI certification for Indian manufacturers and marked with the Standard Mark.
How ERCS Private Limited Can Help in BIS Certification for Ferrosilicon Inoculants
ERCS Private Limited is here to assist in all aspects of production, importing, and supplying your ferrosilicon and inoculant products:
- Correctly mapping your product according to Table 1 or Table 2 grade
- Preparation and submission of documentation for BIS application
- Sample testing, including reporting of residual elements
- Preparation for BIS audit of your factory
- Packaging and labelling as per Clauses 11 and 12
Anushka Pandey
Content WriterShe is an experienced content writer at ERCS Pvt. Ltd., an organization that assists companies with certification and regulatory support. She writes informative content on government certifications su...