We are Riddhi Siddhi Impex, a Mumbai-based supplier and stockist of Stainless Steel 321 Sheets & Plates, established in 2002. We stock titanium-stabilised austenitic sheets and plates to ASTM A240 / ASME SA-240 starting from 3.8 mm thick. We maintain a monthly supply capacity of 400-500 tonnes and export to more than 60 countries. Our company is ISO 9001, 14001, and 45001 certified. We offer EN 10204 Type 3.1/3.2 certificates on request.
Stainless Steel 321 sheets and plates are flat-rolled austenitic stainless steel stabilised with titanium, holding 17-19% chromium and 9-12% nickel. The titanium ties up carbon as stable carbide, so welded joints resist intergranular attack through the 425 to 815°C sensitisation band. Corrosion resistance mirrors Type 304. Hot strength holds far higher, so fabricators pick Grade 321 stainless steel sheet for heated equipment. Stainless Steel 321 sheets and plates are typically used for high-temperature welded equipment like aircraft exhaust systems.
As a reliable 321 stainless steel sheet and plates supplier, we maintain a ready inventory of these flat products in Mumbai, sourced from reputed primary mills. Cold-rolled sheets run 3.8 mm to 6 mm; Hot-rolled plates are available from 6 mm and above. Material ships annealed, with EN 10204 Type 3.1 / 3.2 mill test certificates on request.
We provide 321 SS sheets and plates to ASTM A240 / ASME SA-240 in the annealed mill condition, six surface finishes, and custom dimensions from ready stock.
| Parameter | Details |
|---|---|
| Standard | ASTM A240 / ASME SA-240 |
| Thickness (Sheets, CR) | 3.8 mm to 6 mm |
| Thickness (Plates, HR) | 6 mm and above |
| Width | 3 mm to 2000 mm |
| Width Tolerance | ±0.1 mm |
| Condition | Annealed (standard mill) |
| Surface Finish | 2B, BA (Bright Annealed), Scotch-Brite, Matte, Matte PVC, Skin Pass |
| Supply Forms | Hot rolled and Cold rolled |
| Edge | Mill edge |
| Form | Sheets, Plates |
Titanium distinguishes ASTM A240 Type 321 sheets and plates from standard 304 stainless steel. Added at a minimum of five times the carbon and nitrogen content, it stabilises carbon by forming titanium carbides, reducing chromium carbide precipitation during welding.
| Element | Composition (% by weight) |
|---|---|
| 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) | 17.00-19.00 |
| Nickel (Ni) | 9.00-12.00 |
| Titanium (Ti) | 5x(C+N) min, 0.70 max |
| Nitrogen (N) | 0.10 max |
| Iron (Fe) | Balance |
Annealed SA-240 Type 321 sheet reaches 515 MPa minimum tensile strength with 40% elongation, so it presses and folds without cracking. Plates carry the same minimums.
| Property | Value (Annealed) |
|---|---|
|
Tensile Strength, minimum
|
515 MPa (75 ksi) |
|
Yield Strength (0.2% offset), minimum
|
205 MPa (30 ksi) |
|
Elongation in 50 mm, minimum
|
40% |
|
Hardness, maximum
|
217 HBW / 95 HRB |
International buyers can match the 321 stainless steel plate against their regional standard below. We supply every designation listed.
| Country / Standard | Designation |
|---|---|
| USA (UNS) | S32100 |
| Europe (EN) | X6CrNiTi18-10 |
| Germany (W.Nr) | 1.4541 |
| Japan (JIS) | SUS321 |
| China (GB) | 06Cr18Ni11Ti |
| Russia (GOST) | 08Х18Н10Т |
These 6 industries utilise the Alloy 321 sheet and plate we supply. Buyers pick the grade where welded flat product must hold strength under sustained heat.
Process plants form 321 Ti-stabilised stainless plate into reactor shells, tank components, and vessel linings that run above 500 °C. The stabilised structure resists carbide precipitation, so weld seams stay resistant to acid attack where an unstabilised grade sensitises.
Boiler shops fit SS 321 plate on baffles, stack liners, and expansion joints that cycle between ambient and red heat. The grade resists scaling at combustion temperatures, and its creep strength keeps panels true for years.
Refineries specify Type 321 stainless steel plate for heater internals, flare components, and hot separator parts. Long-term exposure within the sensitisation range can cause standard unstabilised austenitic grades to become susceptible to intergranular corrosion.
Aircraft builders order AMS 5510 sheets for exhaust stacks, heat shields, and engine manifold shielding. Grade 321 keeps its strength through heat cycling that exceeds the high-temperature capability of standard 304 stainless steel, and thin BA-finish gauges form cleanly over compound curves.
Exhaust fabricators press SS 321 sheet into converter housings, flexible connectors, and under-body heat shielding. The 40% minimum elongation gives deep-draw headroom, and welded seams keep their ductility through repeated thermal cycling.
Furnace builders line muffles, radiant sections, and annealing covers with Alloy 321 sheet and plate. Oxidation resistance holds to around 900 °C, so liners and radiant panels survive repeated firing cycles without distortion.
Export orders are issued from our Mumbai and Taloja in wooden cases or on pallets, booked for sea freight.
| Parameter | Details |
|---|---|
| Packaging | Wooden cases, pallet packing |
| Incoterms | FOB, CIF, CFR, EXW Mumbai |
| Dispatch Points | Mumbai and Taloja warehouses |
| Standard Lead Time | 4-5 days |
| Urgent Dispatch | 2-3 days |
| Payment Terms | Advance, credit, LC |
| Certification | EN 10204 Type 3.1 / 3.2 mill test certificates on request |
Stainless Steel 321 Sheets & Plates price in India currently runs around ₹250 to ₹380 per kg, roughly $2.6 to $4.0 per kg for export buyers. The rate tracks nickel and ferrochrome benchmarks; thickness, finish, and volume all move the figure. Call or WhatsApp us for today's rate.
We stock Stainless Steel 321 Sheets & Plates in thicknesses from 3.8 mm and above and widths from 3 mm to 2000 mm. Custom dimensions are available on request.
The difference between SS 321 sheets and SS 321 plates lies in thickness route. Sheets are cold rolled from 3.8 mm to 6 mm; plates are hot rolled from 6 mm upward. Both conform to ASTM A240.
You should choose Stainless Steel 321 Sheets & Plates over SS 304 for hot service because titanium stops chromium carbide from forming at grain boundaries. SS 304 sensitises between 425 and 815 °C; SS 321 resists intergranular corrosion through that band.
Stainless Steel 321 Sheets & Plates ship with EN 10204 Type 3.1 / 3.2 mill test certificates on request. We operate as an ISO 9001, 14001, and 45001 certified company.
You can source Stainless Steel 321 Sheets & Plates in India from us at Riddhi Siddhi Impex, a supplier, stockist, and exporter. Our Mumbai warehouse holds SS321 plate and sheet stock for immediate dispatch across India and overseas. Phone or WhatsApp us; we will provide quotations within 24 hours.
