Quick Answer
Quick Answer
IS 6911 is the Bureau of Indian Standards (BIS) specification for stainless steel sheet, strip, and plate. It covers austenitic, ferritic, and martensitic grades with chemical composition and mechanical property requirements broadly aligned with ISO and ASTM equivalents. Widely used in Indian fabrication shops and service centers.
IS 6911 is published by the Bureau of Indian Standards (BIS) under the steel sectional committee. It is the primary Indian standard governing flat-rolled stainless steel products: sheet, strip, and plate. The standard is used extensively in Indian fabrication shops, pressure vessel manufacturers, food processing equipment makers, and metals service centers.
Understanding IS 6911 is essential for any company sourcing or procuring stainless steel within India, as domestic mills issue test reports referencing IS 6911 designations, and many Indian project specifications require IS-certified material.
Scope
IS 6911 covers:
- Sheet: typically < 4.75 mm thick, width ≥ 600 mm
- Strip: width < 600 mm
- Plate: thickness ≥ 4.75 mm
The standard covers hot-rolled and cold-rolled product in the annealed (solution-treated) and pickled condition. It does not cover bar, pipe, tube, or fittings — those are addressed by separate IS standards.
Grade Designation System
IS 6911 uses a designation system that combines a material code number with a grade suffix. Grades are organized into austenitic, ferritic, and martensitic families:
| IS 6911 Grade | Approximate Equivalent | UNS |
|---|---|---|
| 04Cr18Ni10 | 304 | S30400 |
| 02Cr18Ni11 | 304L | S30403 |
| 04Cr17Ni12Mo2 | 316 | S31600 |
| 02Cr17Ni12Mo2 | 316L | S31603 |
| 04Cr17Ni12Mo2Ti | 316Ti | S31635 |
| 04Cr18Ni11Ti | 321 | S32100 |
| 04Cr18Ni11Nb | 347 | S34700 |
| 04Cr13 | 410S (ferritic/martensitic) | S41008 |
| 06Cr13 | 410 | S41000 |
The grade naming convention in the latest edition uses the chemical composition directly (e.g., 02Cr18Ni11 = max 0.02% C, ~18% Cr, ~11% Ni).
Chemical Composition Requirements
The following composition limits apply to commonly used IS 6911 grades:
| Grade | C max | Mn max | Si max | Cr | Ni | Mo |
|---|---|---|---|---|---|---|
| 04Cr18Ni10 (304) | 0.07 | 2.00 | 1.00 | 17.0–20.0 | 8.0–10.5 | — |
| 02Cr18Ni11 (304L) | 0.030 | 2.00 | 1.00 | 17.0–20.0 | 9.0–12.0 | — |
| 04Cr17Ni12Mo2 (316) | 0.07 | 2.00 | 1.00 | 16.0–18.5 | 10.0–14.0 | 2.0–2.5 |
| 02Cr17Ni12Mo2 (316L) | 0.030 | 2.00 | 1.00 | 16.0–18.5 | 10.5–14.0 | 2.0–2.5 |
P ≤ 0.045%, S ≤ 0.030% for most austenitic grades. Refer to current BIS edition for complete limits.
Compared to ASTM A240, IS 6911 generally allows a slightly wider chromium range and permits Si up to 1.00% (vs 0.75% in A240). This means IS-certified material may not always meet ASTM composition limits and vice versa.
Mechanical Property Requirements
IS 6911 specifies tensile properties at room temperature. For austenitic grades in the annealed condition:
| Grade | 0.2% PS min (N/mm²) | UTS min (N/mm²) | Elongation min % |
|---|---|---|---|
| 04Cr18Ni10 (304) | 205 | 515 | 35 |
| 02Cr18Ni11 (304L) | 170 | 485 | 35 |
| 04Cr17Ni12Mo2 (316) | 205 | 515 | 35 |
| 02Cr17Ni12Mo2 (316L) | 170 | 485 | 35 |
Elongation is measured on a gauge length of 5.65√A (where A = cross-sectional area), consistent with ISO practices.
Hardness limits are also specified; Brinell hardness must not exceed values defined in the standard for each grade.
Surface Finish Designations
IS 6911 uses a finish designation system similar to ASTM A240:
| IS Designation | Description |
|---|---|
| No. 1 | Hot-rolled, annealed, descaled (rough finish) |
| No. 2D | Cold-rolled, annealed, pickled, dull finish |
| No. 2B | Cold-rolled, annealed, light skin-pass, smooth — most common |
| No. 4 | Brushed finish (150-grit equivalent) |
| BA | Bright annealed |
| No. 8 | Mirror polished |
For food, pharmaceutical, and architectural applications, finish specification is critical and must be explicitly stated on the purchase order.
BIS Certification Mark (ISI Mark)
Products manufactured to IS 6911 by BIS-licensed manufacturers carry the ISI Mark (Standard Mark). This mark indicates that the manufacturer's production process has been audited by BIS and that routine surveillance testing is conducted.
For government projects, public sector undertakings (PSUs), and infrastructure projects in India, ISI-marked material is often mandatory. Service centers should verify that their mill suppliers hold valid BIS licenses for IS 6911.
Test Report Requirements Under IS 6911
IS 6911 requires the manufacturer to supply a test certificate containing:
- Manufacturer's name and address
- BIS license number (if ISI-marked)
- Standard reference (IS 6911 and edition year)
- Grade designation
- Heat/cast number
- Product dimensions and quantity
- Chemical composition (ladle analysis)
- Mechanical test results
- Heat treatment condition
- Authorized signatory
While IS 6911 does not directly reference EN 10204, many Indian mills issue test reports in an EN 10204 3.1-compatible format to satisfy export customers. Buyers should specify the required certificate format explicitly.
IS 6911 in the Export Context
When Indian-manufactured stainless steel plate is being used in export projects:
- For ASME code vessels: IS 6911 is not an accepted ASME material. The material must be dual-certified to ASTM A240 / ASME SA-240.
- For EU PED projects: EN 10028-7 certification is required. IS 6911 is not a harmonized EN standard.
- For domestic Indian projects: IS 6911 alone is typically sufficient, and ISI marking may be required for certain regulated sectors.
Frequently Asked Questions
Is IS 6911 equivalent to ASTM A240?
The grades are broadly similar, but IS 6911 and ASTM A240 are not identical. Composition windows differ in some elements (notably Si and S), and the elongation gauge length calculation differs. Material can only be dual-certified if it meets the tighter limits of both standards simultaneously. Verify with the mill before specifying dual certification.
Where can I download IS 6911?
IS standards are published by the Bureau of Indian Standards (BIS) and are available for purchase through the BIS online portal (bis.gov.in) or from BIS regional offices. IS 6911 is not freely available online — purchase of the document from BIS is required for official use.
What does the ISI mark on stainless steel plate signify?
The ISI (Indian Standards Institution) mark, now administered by BIS, indicates that the product has been manufactured by a BIS-licensed facility, meets IS 6911 requirements, and is subject to ongoing surveillance inspections. It provides assurance of quality beyond a single MTC.
Does IS 6911 cover duplex stainless steel?
Later editions of IS 6911 have expanded grade coverage to include duplex grades. However, for critical applications, it is advisable to verify the specific grade is listed in the current edition, as BIS standards are revised periodically and not all editions include the same grade range.
Can a service center in India issue an IS 6911 test certificate?
No. Test certificates under IS 6911 must be issued by the manufacturer of the material, not by a service center or distributor. If a service center cuts or processes the material, it can issue a material traceability document referencing the original mill certificate, but it cannot issue a new IS 6911 test certificate.
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