AISI 321 is a titanium-stabilized austenitic grade (UNS S32100 / EN 1.4541) chosen for its resistance to sensitization, dependable high-temperature strength, and clean weldability. Our SS 321 Square Bar is available in bright, hot rolled, cold drawn, and forged conditions, with custom cutting on request.
Whether you need a single project lot or a bulk export order, we supply material that meets the spec on paper and on the bench.
Stainless Steel Square Bars
Stainless Steel Square Bars
Stainless Steel Square Bars
What Is ASTM A276 AISI 321 Stainless Steel Square Bar
AISI 321 is an austenitic stainless steel stabilized with titanium. That titanium addition ties up free carbon, which stops chromium carbide from forming at the grain boundaries during welding or sustained heat.
The practical result is strong resistance to sensitization and intergranular corrosion. This matters most in the 425–815°C range, where unstabilized grades like 304 tend to lose corrosion performance after welding.
A square profile gives you flat, parallel faces that seat cleanly into frames, fixtures, and machined assemblies. For fabricators, that means less prep work and tighter fit-up. The grade is recognized worldwide as UNS S32100 and EN 1.4541, so it slots easily into international procurement specs.
Key Features and Benefits of SS 321 Square Bar
The value of 321 square bar comes down to how it behaves under heat and after welding. Titanium stabilization prevents weld decay, so you can fabricate heavy or welded sections without mandatory post-weld annealing.
It holds useful strength and creep resistance up to roughly 800°C, with solid oxidation resistance during thermal cycling. General corrosion resistance stays close to 304, while the stabilized structure handles repeated heating far better.
Consistent square dimensions also help. Parallel faces and controlled tolerances make machining, drilling, and assembly more predictable on the shop floor.
ASTM A276 AISI 321 Square Bar Specifications
Here is a quick reference for the core specifications we supply against.
| Property | Detail |
|---|---|
| Standard | ASTM A276 / ASTM A479 / ASME SA276 |
| Grade | AISI 321 / UNS S32100 / EN 1.4541 |
| Product Form | Square Bar |
| Size Range | 4 mm – 500 mm side (custom available) |
| Length | 2–6 m or custom cut lengths |
| Finishes | Bright, Hot Rolled, Cold Drawn, Forged, Polished |
| Manufacturing Process | Hot Rolled, Cold Drawn, Forged, Machined |
| Tolerance | h8 / h9 / h11 as required |
If your drawing calls for a size outside this range, send it through. We cut and finish to order.
Chemical Composition of AISI 321 Square Bar
The composition is what gives 321 its corrosion resistance and stability. Chromium and nickel build the austenitic, corrosion-resistant base, while titanium does the stabilizing work that defines the grade.
| Element | Content (%) |
|---|---|
| Carbon (C) | 0.08 max |
| Manganese (Mn) | 2.00 max |
| Silicon (Si) | 1.00 max |
| Phosphorus (P) | 0.045 max |
| Sulfur (S) | 0.030 max |
| Chromium (Cr) | 17.00 – 19.00 |
| Nickel (Ni) | 9.00 – 12.00 |
| Titanium (Ti) | 5 x C min – 0.70 max |
| Iron (Fe) | Balance |
The titanium content is the detail to watch. It is what keeps carbon from migrating to the grain boundaries under heat.
Mechanical Properties of Stainless Steel 321 Square Bar
SS 321 Square Bar combines good tensile strength with high ductility, which suits both structural and machined parts. Values shift slightly with product form and heat treatment, so the figures below represent typical annealed condition.
| Property | Value |
|---|---|
| Tensile Strength | 515 MPa min |
| Yield Strength (0.2% Proof) | 205 MPa min |
| Elongation | 40% min |
| Hardness (Brinell, HB) | 217 max |
| Hardness (Rockwell B, HRB) | 95 max |
| Density | 7.93 g/cm³ |
For specific creep or stress-rupture data tied to a design temperature, we can share figures on request.
Physical Properties of UNS S32100 Square Bar
Physical properties help engineers plan for thermal expansion, heat transfer, and fabrication behavior. The data below supports applications involving elevated temperatures and welded assemblies.
| Property | Value |
|---|---|
| Density | 7930 kg/m³ |
| Melting Range | 1398–1446 °C |
| Thermal Conductivity (100°C) | 16.3 W/m·K |
| Specific Heat (0–100°C) | 500 J/kg·K |
| Thermal Expansion | 16.6 µm/m·°C |
| Electrical Resistivity | 0.72 µΩ·m |
| Elastic Modulus | 193 GPa |
| Magnetic Permeability | 1.02 |
Equivalent Grades and International Standards
AISI 321 is accepted across most major procurement specs, which makes cross-border sourcing straightforward. The table maps the grade to its regional equivalents.
| Region / Body | Grade | Standard |
|---|---|---|
| USA (ASTM/ASME) | AISI 321 / UNS S32100 | ASTM A276, A479, A182, ASME SA276 |
| Europe (EN) | 1.4541 | EN 10088-3 |
| Germany (DIN) | X6CrNiTi18-10 | DIN 17440 |
| UK (BS) | 321S31 | BS 970 |
| France (AFNOR) | Z6CNTi18-10 | NF A35-573 |
| Japan (JIS) | SUS 321 | JIS G4303 |
| China (GB) | 0Cr18Ni10Ti | GB/T 1220 |
| Russia (GOST) | 08Х18Н10Т | GOST 5632 |
If your project documents reference one of these regional codes, we can supply matching certification.
Available Sizes and Finishes for SS 321 Square Bar
We stock 321 square bar across a wide size band and in several finishes, so you can match the bar to the job rather than reworking it.
Hot rolled bars cover larger sections for structural and high-temperature frameworks. Cold drawn bars give tighter tolerances and a smoother surface. Bright bars suit precision machining, while forged bars handle large or custom dimensions. Polished finishes are available where surface appearance matters.
Beyond standard stock, we offer custom cutting, cut-to-length service, and ready stock for faster turnaround. Send your size and finish requirement, and we will confirm availability and dispatch time.
Testing and Certification for ASTM A276 321 Square Bar
Every batch is verified before it leaves our facility, and full documentation travels with the material. Our standard testing and certification covers the checks most buyers and inspectors ask for:
PMI (Positive Material Identification) to confirm grade and titanium content
Material Test Certificates (MTC) as per EN 10204 3.1
Tensile, hardness, and chemical analysis per ASTM standards
Intergranular corrosion test per ASTM A262, with ultrasonic testing per ASTM A388
Third-party inspection from agencies such as SGS, TÜV, BV, or Lloyd's is available on request. We also provide 100% dimensional and visual inspection along with complete material traceability.
Industrial Applications of AISI 321 Square Bar
The grade earns its place wherever heat and welding meet corrosive service. In petrochemical and chemical processing, it goes into welded tanks, pressure vessels, and piping.
Refineries and power plants use it for furnace components and superheater parts, where stability under sustained heat is non-negotiable. Aerospace work draws on it for exhaust manifolds, heat exchangers, and structural components.
You will also find 321 square bar in automotive exhaust systems, hygienic food processing equipment, and general fabrication, including frames, supports, and machined parts. The common thread is reliable performance after welding and during thermal cycling.
Why Choose Steel House India for ASTM A276 321 Square Bar
We work as a manufacturer, supplier, and stockist of ASTM A276 AISI Stainless Steel 321 Square Bar in India, which means you deal with one source from inquiry to dispatch. Ready stock across common sizes keeps lead times short.
Custom cutting and cut-to-length service let you order the exact dimensions your drawing calls for, instead of buying excess and trimming it down. Our material ships with full MTC, PMI reports, and third-party inspection support when your project requires it.
For export buyers, we handle seaworthy packing and complete documentation. As an ASTM A276 AISI Stainless Steel 321 Square Bar supplier in India with pan-India reach, we support both single-project orders and bulk volumes without dropping the quality checks.
Frequently Asked Questions — ASTM A276 AISI 321 Square Bar
What is ASTM A276 AISI 321 stainless steel square bar?
It is a titanium-stabilized austenitic stainless steel bar (UNS S32100 / EN 1.4541) produced to the ASTM A276 specification, supplied in a square profile for structural, welded, and machined applications.
What is the difference between 321 and 304 stainless steel square bar?
Both share a similar base composition, but 321 adds titanium to prevent chromium carbide precipitation under heat. That makes 321 the better choice for welded parts and high-temperature service where 304 would risk sensitization.
Is SS 321 square bar suitable for high-temperature applications?
Yes. It holds strength and corrosion resistance through the 425–815°C range and resists oxidation during thermal cycling, which is why it is common in furnaces, exhaust systems, and refinery equipment.
What sizes and finishes are available in ASTM A276 321 square bar?
We stock sides from roughly 4 mm to 500 mm in bright, hot rolled, cold drawn, forged, and polished finishes, with custom cutting available on request.
Do you provide MTC and third-party inspection for 321 square bar?
Yes. Every order ships with Material Test Certificates as per EN 10204 3.1, and third-party inspection from agencies like SGS, TÜV, or BV can be arranged on request.
Are you a manufacturer, supplier, and stockist of 321 square bar in India?
Yes. Steel House India is a manufacturer, supplier, and stockist of ASTM A276 AISI Stainless Steel 321 Square Bar in India, with ready stock and pan-India delivery.
How quickly can you dispatch and deliver across India?
Standard sizes held in ready stock ship quickly after order confirmation. Custom sizes and finishes depend on dimensions and quantity, and we confirm a dispatch timeline with every quote.
Request a Quote for ASTM A276 AISI 321 Square Bar
Tell us what you need and we will get you a clear, competitive quote. To speed things up, share the shape, dimensions (side and length), finish, and quantity.
Reach us for a quote by email or WhatsApp, and ask about ready stock, custom cutting, and pan-India delivery. As an ASTM A276 AISI Stainless Steel 321 Square Bar stockist in India, we are ready to supply the exact material your project specifies.