Steel House India manufactures, supplies, and stocks ASTM A276 AISI Stainless Steel 304L Square Bars in India — available in sizes from 10 x 10 mm to 150 x 150 mm, in hot-rolled, cold-drawn, and bright-finished conditions, with EN 10204 3.1 material certification on every order. We have been supplying SS 304L square bars to pharmaceutical, chemical, food processing, and fabrication industries since 1992, and we hold ISO 9001:2015 certification across our manufacturing and supply operations.
If you are sourcing 304L square bars for welded assemblies, pressure systems, or corrosion-critical applications in India, this page gives you everything you need to confirm the specification, size, and standard before you place your order.
What Does ASTM A276 AISI 304L Mean — and Why Does It Matter for Your Application?
Stainless Steel Square Bars
Stainless Steel Square Bars
Stainless Steel Square Bars
ASTM A276 is the American standard that governs the dimensions, tolerances, mechanical properties, and surface finish of stainless steel bars — including square bars, round bars, and hex bars. AISI 304L is the low-carbon variant of Grade 304, designated UNS S30403 and EN 1.4307 under European standards.
The "L" in 304L stands for low carbon, with carbon capped at 0.03% maximum. This single difference determines whether a welded assembly holds its corrosion resistance after fabrication — or corrodes at the weld zone within months.
For buyers comparing 304 and 304L, here is what the grade difference actually means in procurement and fabrication terms:
| Property | SS 304 Square Bar | SS 304L Square Bar |
|---|---|---|
| Carbon Content (max) | 0.08% | 0.03% |
| UNS Designation | S30400 | S30403 |
| EN Equivalent | 1.4301 | 1.4307 |
| Sensitization Risk During Welding | Present in thicker sections | Negligible — low carbon limits carbide precipitation |
| Post-Weld Heat Treatment Required | Recommended for corrosive service | Not required for most welded applications |
| Tensile Strength (min, annealed) | 515 MPa | 485 MPa |
| Yield Strength (min, annealed) | 205 MPa | 170 MPa |
| Hardness (max) | 201 HB | 187 HB |
If your fabrication involves welding, and the finished part will operate in a corrosive or hygienic environment, SS 304L is the correct grade. Standard 304 is a better fit for machining-focused applications where welding is limited.
What Is the Chemical Composition of ASTM A276 304L Square Bars?
Every SS 304L square bar we supply conforms to the chemical limits defined under ASTM A276 for UNS S30403. The composition below is not just a datasheet reference — each element plays a specific role in how the bar performs in your application.
| Element | Symbol | Limit (%) |
|---|---|---|
| Carbon | C | 0.030 max |
| Chromium | Cr | 18.00 – 20.00 |
| Nickel | Ni | 8.00 – 12.00 |
| Manganese | Mn | 2.00 max |
| Silicon | Si | 1.00 max |
| Phosphorus | P | 0.045 max |
| Sulfur | S | 0.030 max |
The combination of 18–20% chromium and 8–12% nickel with very low carbon is what makes 304L the standard choice for welded process equipment across pharmaceutical, food, and chemical industries.
What Are the Mechanical Properties of ASTM A276 304L Square Bars?
Mechanical properties for 304L square bars vary depending on the manufacturing condition — hot-finished or cold-finished — and the section size. The values below are for Condition A (annealed), which is the standard supply condition for most industrial applications.
| Mechanical Property | Hot-Finished | Cold-Finished ≤12.70 mm | Cold-Finished >12.70 mm |
|---|---|---|---|
| Tensile Strength (min) | 485 MPa [70 ksi] | 620 MPa [90 ksi] | 485 MPa [70 ksi] |
| Yield Strength (min) | 170 MPa [25 ksi] | 310 MPa [45 ksi] | 170 MPa [25 ksi] |
| Elongation in 50 mm (min) | 40% | 30% | 30% |
| Reduction of Area (min) | 50% | 40% | 40% |
| Hardness (typical) | 187 HB max | 187 HB max | 187 HB max |
Hot-finished bars are commonly used for structural and fabrication applications where machining allowances are acceptable. Cold-finished bars deliver tighter tolerances and improved surface quality, making them the preferred choice for precision-fabricated components and close-tolerance assemblies.
If your application requires higher strength — such as Condition B or strain-hardened Condition S — we supply those on request. Share your section size and application, and we will confirm the achievable properties before the order is placed.
What Sizes, Lengths, and Surface Finishes Are Available for SS 304L Square Bars?
We stock SS 304L square bars from 10 x 10 mm up to 150 x 150 mm, with larger sections available on production order. The finish you choose affects not just appearance but dimensional tolerance, surface roughness, and suitability for your end use.
| Size / Finish Type | Available Range | Best Suited For |
|---|---|---|
| Hot Rolled (Black) | 25 x 25 mm to 150 x 150 mm | Structural fabrication, weld assemblies, general engineering |
| Cold Drawn (Bright) | 10 x 10 mm to 50 x 50 mm | Precision machining, close-tolerance fabrication |
| Peeled / Turned | 25 x 25 mm to 100 x 100 mm | Shaft blanks, heavy machining stock |
| Polished (No. 4 / BA) | 10 x 10 mm to 50 x 50 mm | Food-grade, pharmaceutical, hygienic systems |
Standard lengths range from 3 m to 6 m in random mill lengths. We also cut to your required lengths. For cold-drawn bars, dimensional tolerances follow BS 970 Part 3 (all-minus):
• 6 mm to 18 mm: −0.09 mm
• Over 18 mm to 30 mm: −0.11 mm
• Over 30 mm to 50 mm: −0.13 mm
• Over 50 mm to 80 mm: −0.16 mm
• Over 80 mm to 105 mm: −0.25 mm
If you need a non-standard size, a specific surface roughness value, or a particular length, we cut, grind, and polish to your drawing.
What International Standards and Equivalent Grades Apply to 304L Square Bars?
When your project references drawings from international clients or involves export inspection, knowing the equivalent grade designation prevents procurement delays and certification disputes.
| Standard System | Grade Designation | UNS Number | Carbon Limit (%) |
|---|---|---|---|
| ASTM A276 (USA) | Type 304L | S30403 | 0.030 max |
| AISI / SAE (USA) | 304L | S30403 | 0.030 max |
| EN (Europe) | 1.4307 | S30403 | 0.030 max |
| DIN (Germany) | X2CrNi18-9 | S30403 | 0.030 max |
| BS (UK) | 304S11 | S30403 | 0.030 max |
Every material certificate we supply references the applicable standard and UNS number. Your QA team can verify conformance against the certificate without needing to cross-reference separately.
Why Do Welded Fabrications Require 304L Instead of Standard 304?
Standard 304 contains up to 0.08% carbon. During welding, heat drives that carbon to bond with chromium at the grain boundaries — a process called sensitization. The result is chromium depletion in the heat-affected zone, which opens the material to intergranular corrosion.
304L limits carbon to 0.03% max. At that level, the carbide-forming reaction during welding is reduced to the point where the heat-affected zone retains its corrosion resistance without post-weld annealing.
For procurement teams specifying material for welded pressure vessels, chemical tanks, food processing frames, or pharmaceutical pipework, 304L removes a failure mode that standard 304 cannot eliminate at the composition level.
Which Industries Use ASTM A276 304L Square Bars — and for What Components?
The combination of low carbon, high chromium-nickel composition, and square cross-section geometry makes 304L square bars a practical choice across a wide range of fabricated industrial components.
| Size (mm x mm) | Section Area (mm²) | Theoretical Weight (kg/m) | Perimeter (mm) | Moment of Inertia (cm⁴) | Section Modulus (cm³) |
|---|---|---|---|---|---|
| 10 x 10 | 100 | 0.785 | 40 | 0.083 | 0.167 |
| 12 x 12 | 144 | 1.130 | 48 | 0.173 | 0.288 |
| 16 x 16 | 256 | 2.010 | 64 | 0.546 | 0.683 |
| 20 x 20 | 400 | 3.140 | 80 | 1.333 | 1.333 |
| 25 x 25 | 625 | 4.906 | 100 | 3.255 | 2.604 |
| 30 x 30 | 900 | 7.065 | 120 | 6.750 | 4.500 |
| 40 x 40 | 1600 | 12.560 | 160 | 21.333 | 10.667 |
| 50 x 50 | 2500 | 19.625 | 200 | 52.083 | 20.833 |
| 65 x 65 | 4225 | 33.166 | 260 | 148.877 | 45.808 |
| 80 x 80 | 6400 | 50.240 | 320 | 341.333 | 85.333 |
| 100 x 100 | 10000 | 78.500 | 400 | 833.333 | 166.667 |
| 150 x 150 | 22500 | 176.625 | 600 | 4218.750 | 562.500 |
We supply 304L square bars into oil and gas, refinery, pharmaceutical, paper and pulp, power generation, shipbuilding, cement, and aerospace fabrication projects across India.
How Are SS 304L Square Bars Manufactured — and Why Does the Process Affect Performance?
The manufacturing route determines the bar's dimensional accuracy, hardness consistency, surface finish, and machinability. Buyers sourcing for tight-tolerance applications should understand which process produces which result.
| Specification Parameter | Standard / Method | Value / Range |
|---|---|---|
| Size Range | BS 970 Part 3 / ASTM A276 | 10 x 10 mm to 150 x 150 mm |
| Length (Random Mill) | ASTM A276 | 3 m to 6 m |
| Dimensional Tolerance (Cold Drawn) | BS 970 Part 3 (all-minus) | −0.09 mm to −0.25 mm depending on size |
| Straightness (Cold Drawn) | ASTM A276 | 0.5 mm per 1000 mm max |
| Surface Roughness — Bright / Cold Drawn | Ra (µm) | 0.8 – 1.6 µm |
| Surface Roughness — Polished (No. 4 / BA) | Ra (µm) | 0.4 – 0.8 µm |
| Surface Roughness — Hot Rolled (Black) | Ra (µm) | 6.3 – 12.5 µm |
| Hardness (Annealed Condition A) | Brinell (HB) | 187 HB max |
| Carbon Content (max) | ASTM A276 / UNS S30403 | 0.030% |
We monitor every step in the process. The finished bar you receive matches the dimensions, condition, and surface finish you ordered — not an approximation of it.
What Testing and Certification Do We Provide with Every Order?
Many suppliers ship with a basic mill certificate. We supply full documentation so your incoming inspection and QA records are complete without follow-up requests.
| Size (mm × mm) | Tolerance (mm) | Weight (kg/m) | Length Available | Surface Condition |
|---|---|---|---|---|
| 10 × 10 | −0.09 | 0.785 | 3 m – 6 m | Cold Drawn / Bright |
| 16 × 16 | −0.09 | 2.010 | 3 m – 6 m | Cold Drawn / Bright |
| 20 × 20 | −0.11 | 3.140 | 3 m – 6 m | Cold Drawn / Bright |
| 25 × 25 | −0.11 | 4.906 | 3 m – 6 m | Cold Drawn / Hot Rolled |
| 30 × 30 | −0.13 | 7.065 | 3 m – 6 m | Cold Drawn / Hot Rolled |
| 40 × 40 | −0.13 | 12.560 | 3 m – 6 m | Cold Drawn / Hot Rolled |
| 50 × 50 | −0.13 | 19.625 | 3 m – 6 m | Cold Drawn / Peeled |
| 65 × 65 | −0.16 | 33.166 | 3 m – 6 m | Hot Rolled / Peeled |
| 80 × 80 | −0.16 | 50.240 | 3 m – 6 m | Hot Rolled / Peeled |
| 100 × 100 | −0.25 | 78.500 | 3 m – 6 m | Hot Rolled / Rough Turned |
| 150 × 150 | ASTM Tolerance | 176.625 | 3 m – 6 m | Hot Rolled / Forged |
All products are tested and certified under our ISO 9001:2015 quality system. We track heat numbers from raw material through to the finished bar, so traceability is complete at every stage.
Why Source ASTM A276 304L Square Bars from Steel House India?
Industrial buyers in India choosing between manufacturers, traders, and stockists need to know exactly what they are getting — not just a grade name and a price.
| Size (mm × mm) | Side Tolerance (mm) | Weight (kg/m) | Straightness (max) | Surface Condition |
|---|---|---|---|---|
| 10 × 10 | −0.09 | 0.785 | 0.5 mm/1000 mm | Cold Drawn / Bright |
| 16 × 16 | −0.09 | 2.010 | 0.5 mm/1000 mm | Cold Drawn / Bright |
| 20 × 20 | −0.11 | 3.140 | 0.5 mm/1000 mm | Cold Drawn / Bright |
| 25 × 25 | −0.11 | 4.906 | 0.5 mm/1000 mm | Cold Drawn / Hot Rolled |
| 30 × 30 | −0.13 | 7.065 | 0.5 mm/1000 mm | Cold Drawn / Hot Rolled |
| 40 × 40 | −0.13 | 12.560 | 0.5 mm/1000 mm | Cold Drawn / Hot Rolled |
| 50 × 50 | −0.13 | 19.625 | 1.0 mm/1000 mm | Cold Drawn / Peeled |
| 65 × 65 | −0.16 | 33.166 | 1.0 mm/1000 mm | Hot Rolled / Peeled |
| 80 × 80 | −0.16 | 50.240 | 1.0 mm/1000 mm | Hot Rolled / Peeled |
| 100 × 100 | −0.25 | 78.500 | 1.5 mm/1000 mm | Hot Rolled / Rough Turned |
| 150 × 150 | ASTM Tolerance | 176.625 | 1.5 mm/1000 mm | Hot Rolled / Forged |
We stand behind every bar we supply. If the material does not meet the specification on your purchase order, we resolve it — without delay and without excuses.
Comparing SS 304L Square Bars with Adjacent Grades
If your application requires a different grade, the two options buyers most commonly evaluate alongside 304L are covered in our dedicated pages for Stainless Steel 304 Square Bars and Stainless Steel 316 Square Bars.
Request a Quote for ASTM A276 304L Square Bars
Tell us your size, finish, length, quantity, and certification requirement. We confirm stock availability and pricing the same day for standard sizes. For non-standard sizes or large-volume orders, we provide a production lead time and full documentation schedule upfront.
Steel House India is your manufacturer, supplier, and stockist for ASTM A276 AISI Stainless Steel 304L Square Bars in India. Contact our team today to confirm availability and place your order.