We are Riddhi Siddhi Impex, a Mumbai-based supplier and stockist of Stainless Steel 309 Sheets & Plates, established in 2002. Our warehouses stock ASTM A240 / ASME SA-240 flat stock from 3.8 mm, a heat-resistant grade containing 22-24% chromium and 12-15% nickel. As an ISO 9001, 14001, and 45001 certified company, our every dispatch is backed by EN 10204 Type 3.1 / 3.2 mill test certifications available upon request.
Stainless Steel 309 sheets and plates are heat-resisting austenitic grade flat-rolled products alloyed with 22-24% chromium and 12-15% nickel. Its oxide scale withstands continuous service in air to roughly 1095 °C and intermittent (cyclic) service to about 980 °C. ASTM A240 covers the flat-rolled form as 309S (UNS S30908), capping carbon at 0.08%, so sheet and plate weld cleanly. One caution applies: extended holds between 600 and 950°C form the sigma phase, cutting room-temperature ductility. Stainless Steel 309 sheets and plates are typically used in furnace parts, heating elements, aircraft jet engine components, and high-temperature chemical processing equipment.
We are reliable 309 stainless steel sheet suppliers, hence many buyers source this grade from our stainless steel sheets and plates inventory, which includes cold-rolled sheets from 3.8 mm and hot-rolled plates slit to any width between 3 mm and 2000 mm, with a tolerance of ±0.1 mm. Material sits annealed at Mumbai and Taloja; each consignment carries an EN 10204 Type 3.1 or 3.2 certificate on request.
We provide SS 309 sheets and plates to ASTM A240 / ASME SA-240 in annealed condition, with AMS 5523 cover for aerospace orders and slitting to working width.
| Parameter | Details |
|---|---|
| Standard | ASTM A240 / ASME SA-240 (general: ASTM A480) |
| Aerospace Standard | AMS 5523 |
| Thickness (Sheet) | 3.8 mm to 6 mm |
| Thickness (Plate) | 6 mm and above |
| Width | 1000, 1250, 1500, 2000 mm; slit widths from 3 mm |
| Length | 2000, 2500, 6000 mm; custom |
| Surface Finish | No.1 (HR annealed pickled), 2B (CR annealed pickled) |
| Form | Hot Rolled Plate, Cold Rolled Sheet |
| Condition | Annealed |
Chromium between 22.0 and 24.0% gives Type 309 its scaling resistance, while 12.0-15.0% nickel keeps the structure austenitic through cycling. Limits below follow ASTM A240 for 309S.
| Element | Composition (%) |
|---|---|
| Carbon (C) | 0.08 max |
| Manganese (Mn) | 2.00 max |
| Phosphorus (P) | 0.045 max |
| Sulphur (S) | 0.030 max |
| Silicon (Si) | 0.75 max |
| Chromium (Cr) | 22.0-24.0 |
| Nickel (Ni) | 12.0-15.0 |
| Iron (Fe) | Balance |
Annealed 309 plate pairs a 515 MPa minimum tensile strength with 40% elongation, so it rolls and forms without cracking. Values follow ASTM A240 for annealed flat products.
| Property | Value |
|---|---|
|
Tensile Strength (min)
|
515 MPa (75 ksi) |
|
Yield Strength, 0.2% offset (min)
|
205 MPa (30 ksi) |
|
Elongation in 50 mm (min)
|
40% |
|
Hardness (max)
|
217 HBW / 95 HRB |
International buyers can cross-check the designations below before ordering. The 309S flat-product grade holds recognised equivalents across European, Japanese, Chinese, and Russian systems.
| Country / Standard | Designation |
|---|---|
| USA (UNS) | S30908 |
| Europe (EN) | X12CrNi23-13 |
| Germany (W.Nr) | 1.4833 |
| Japan (JIS) | SUS 309S |
| China (GB) | 06Cr23Ni13 |
| Russia (GOST) | 08Х23Н13 |
These 4 industries widely use the 309 stainless steel plates and sheets leaving our warehouses, each specifying the grade for oxidation resistance at furnace temperatures.
Furnace builders fabricate oven linings, retorts, muffles, and annealing covers from Alloy 309 plate. It holds shape through repeated cycles toward 980°C without heavy scaling. The nickel content improves resistance to carburisation, extending the service life of baskets and trays handling hot workpieces, which resists carbon pickup better than leaner stainless grades.
Boiler baffles, duct sections, and ash-handling chutes in coal and biomass plants use 309 stainless steel sheet. Creep strength keeps these parts flat under sustained load. Where flue gases carry sulphur, moderate nickel limits attack by hot sulphur compounds are better than nickel-richer alloys.
Process licensors specify UNS S30908 plate for sulphur furnaces, catalyst regeneration internals, and fired-heater components. Resistance to oxidising and mildly reducing atmospheres widens its service window. Thermowells and burner shrouds manufactured from Stainless Steel 309 outlast carbon steel parts that scale away within months.
Incinerator operators line combustion chambers and secondary burn zones with SS 309 plates. Feed hoppers, grate surrounds, and quench sections face abrasive ash plus corrosive flue gas together. High chromium keeps renewing the oxide film as surfaces wear, stretching refit intervals on continuously fired plants.
Consignments are issued from our Mumbai and Taloja warehouses sea-worthy, packed to survive port handling.
| Parameter | Details |
|---|---|
| Packaging | Wooden cases, pallet packing |
| Incoterms | FOB, CIF, CFR, EXW Mumbai |
| Dispatch Points | Mumbai and Taloja warehouses |
| Standard Lead Time | 4 to 5 days |
| Urgent Dispatch | 2 to 3 days |
| Payment Terms | Advance, credit, LC |
| Certification | EN 10204 Type 3.1 / 3.2 on request |
SS 309 sheets and plates price in India is around ₹300 to ₹500 per kg. Export buyers pay roughly $3.40 to $5.70 per kg. Nickel rates, thickness, quantity, and finish move the figure, with volume discounts on bulk orders. WhatsApp us for today's rate.
SS 309 plates run continuously to about 1095°C in dry air. Cyclic heating drops the practical limit to roughly 980 °C as expansion and contraction spall the scale.
Yes, SS 309 sheets weld readily by TIG, MIG, and manual arc with 309L filler. The 0.08% carbon cap limits carbide precipitation, so post-weld annealing is rarely needed. Avoid oxyacetylene welding.
Use SS 309 once service temperatures pass roughly 870°C, where SS 304 starts scaling. Higher chromium and nickel carry it through furnace heat; SS 304 stays cost-effective for ambient duty.
You can buy SS 309 sheets and plates in India from us at Riddhi Siddhi Impex. Ready stock at Mumbai and Taloja covers pan-India supply and worldwide export. Send your size requirements for receiving a quotation within 24 hours.
