What material is ASTM A240 304L?

What material is ASTM A240 304L?

When engineers, fabricators, or procurement specialists query "What material is ASTM A240 304L?", they're often seeking clarity on one of the most ubiquitous stainless steels in industrial applications. ASTM A240 304L refers to a low-carbon austenitic stainless steel grade specified under ASTM A240/A240M, the standard for chromium and chromium-nickel stainless steel plate, sheet, and strip for pressure vessels and general applications. This material, also known as UNS S30403, is prized for its excellent weldability, corrosion resistance in mild environments, and formability, making it a staple in food processing, pharmaceuticals, and architectural projects. As a leading manufacturer and exporter in China, Gangsteel produces and supplies ASTM A240 304L plates, sheets, and custom components, ensuring compliance with both ASTM and ASME SA240 standards.

But let's address the nuances behind the search: ASTM A240 304L is the low-carbon variant of Grade 304, with carbon limited to ≤0.03% to minimize carbide precipitation during welding, thus avoiding intergranular corrosion (IGC) without post-weld annealing. It's non-magnetic in the annealed state, offers good strength (yield ≥170 MPa), and resists atmospheric corrosion, dilute acids, and food acids effectively. At Gangsteel, we refine 304L through argon-oxygen decarburization (AOD) for ultra-low carbon and impurities, delivering plates up to 100 mm thick in finishes like 2B, No.4, and electropolished. This grade's PREN (Pitting Resistance Equivalent Number) of ~18-20 provides solid performance in non-chloride settings, though for harsher corrosives, upgrades like 316L are recommended.

In essence, ASTM A240 304L is an austenitic stainless steel optimized for fabrication and mild corrosion resistance, balancing cost (typically USD 3-5/kg in November 2025) with versatility. For related grades in our portfolio, explore ASTM A 240 Gr 304 for standard carbon or ASTM A 240 Gr 304L specifics. Dive deeper into its composition, properties, and uses below.

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1. What is ASTM A240 Grade 304L (S30403)?

ASTM A240 Grade 304L (UNS S30403) is a low-carbon version of the widely used Type 304 austenitic stainless steel, governed by ASTM A240/A240M-22a for plate, sheet, and strip in pressure vessels and general applications. The "L" designation indicates low carbon (≤0.03%), which enhances resistance to sensitization—a process where chromium carbides form at grain boundaries during welding or heating, depleting corrosion protection. This makes 304L ideal for as-welded structures, eliminating the need for costly annealing in many cases, as confirmed by ASTM A262 Practice E testing for IGC.

Historically, 304L evolved from 304 in the mid-20th century to address weld decay in chemical and food industries. At Gangsteel, we produce it from premium electric arc furnace melts, followed by AOD and vacuum degassing for carbon control below 0.025% and inclusion levels <0.01%. The austenitic structure—stabilized by 18-20% Cr and 8-12% Ni—provides non-magnetic properties, excellent ductility for forming (up to 50% reduction), and toughness across -196°C to 870°C. Density is 8.00 g/cm³, with a modulus of 193 GPa for structural calculations.

Common searches like "AISI 304L plate" refer to its legacy designation, but under ASTM A240, it's specified for sanitary and corrosive duties. It offers a thermal conductivity of 16.2 W/m·K and coefficient of expansion of 17.3 × 10⁻⁶/°C, minimizing distortion in assemblies. Weldability is superb with 308L filler; no preheat required, and it passes bend tests per ASTM A240. Compared to ASTM A 240 Gr 304LN, 304L lacks nitrogen strengthening but costs 10-20% less for non-high-strength needs.

In applications like brewery tanks or architectural cladding, 304L's balance of economy and performance shines—our clients report 3-5x longer life than carbon steel in humid environments. For chloride exposure, however, consider ASTM A 240 Gr 316L with molybdenum.

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3. ASTM A240 Grade 304L Chemical Composition

The chemical composition of ASTM A240 Grade 304L is tightly controlled to ensure weld integrity and corrosion resistance, as detailed in ASTM A240 Table 1. Gangsteel’s production achieves even stricter limits through VOD, with carbon consistently ≤0.025%.

This 18-8 formulation (Cr-Ni) creates a passive oxide layer for atmospheric and dilute acid resistance. Low carbon curbs Cr23C6 formation, passing IGC tests even after welding. Nitrogen ≤0.10% adds subtle strengthening without ferrite risk. Our PMI verifies 99.9% compliance, and salt fog exposures show <0.02 mm pitting after 1000 hours.

Note: Compared to ASTM A 240 Gr 304 (C ≤0.08%), 304L trades minor strength for superior weldability. For Mo-added variants, see ASTM A 240 Gr 316.

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3. ASTM A240 Grade 304L Mechanical Properties

ASTM A240 Grade 304L mechanicals emphasize ductility over strength, tested per ASTM E8 in annealed state (1010-1120°C quench).

Low carbon yields softer profile than 304 (yield 205 MPa), perfect for stamping. Fatigue limit ~180 MPa at 10^7 cycles. Impact toughness 150J Charpy at -196°C for cryo apps.

Compared to ASTM A 240 Gr 304H, 304L sacrifices heat strength for weld ease. Machinability 45% of B1112; cold-form to 180° without cracking.

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4. ASTM A240 Grade 304L Allowable Stress

Allowable stresses per ASME BPVC Section II Part D Table 1A guide vessel design.

Supports 8 bar at 300°C with minimal creep. For hotter service, shift to ASTM A 240 Gr 321H. Certs include derating tables.

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5. ASTM A240 Grade 304L Equivalent Materials

ASTM A240 304L equivalents facilitate international procurement, with detailed specs for compatibility.

These are near-identical; EN 1.4307 has Ni 8.0-10.5% vs 8.0-12.0%, but mechanics align. Gangsteel dual-certs for seamless swaps.

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6. ASTM A240 Grade 304L vs ASTM A 240 Gr 304, ASTM A 240 Gr 304H, and ASTM A 240 Gr 316L

Selection hinges on trade-offs; here's a comparison from Gangsteel tests vs ASTM A 240 Gr 304, ASTM A 240 Gr 304H, ASTM A 240 Gr 316L.

• Gr 304L vs 304: 304L’s low C avoids IGC in welds; 304 stronger but needs annealing—304L for heavy fab.
• Gr 304L vs 304H: 304H’s high C boosts heat strength (creep 150 MPa vs 100 MPa at 650°C); 304L for ambient welds.
• Gr 304L vs 316L: 316L’s Mo enhances chlorides (CPT 30°C vs 15°C); 304L cheaper for inland.

Choose 304L for weld/mild corrosion, 304 strength, 304H heat, 316L chlorides.

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7. ASTM A240 Grade 304L Specifications

Gangsteel offers 304L in versatile forms with tight tolerances.

7.1 Plate and Sheet

• Thickness: 0.3-100 mm (plate), 0.2-6 mm (sheet)
• Width: 1000-3000 mm
• Length: 2000-12000 mm/coils
• Surface: 2B, BA, No.4; Ra <0.4 μm electropolished
• Standards: ASTM A240, ASME SA240, AMS 5511
• Uses: Plates for silos, sheets for panels

7.2 Bar and Rod

• Diameter: 4-500 mm
• Length: Up to 12000 mm
• Finish: Peeled, ground
• Standards: ASTM A276, ASME SA479
• Uses: Bolts, shafts

7.3 Custom Components

• Types: Flanges, fittings
• Processes: CNC machined, welded
• Certs: NACE, PED
• Uses: Pharma equipment

Stock: 1200 tons; 7-14 days delivery.

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8. Applications of ASTM A240 Grade 304L

304L’s weldability drives use in:

• Food Processing: Tanks; FDA-compliant, resists organics.
• Pharmaceuticals: Vessels; sterile, CIP tolerant.
• Architecture: Cladding; UV-resistant.
• Chemical: Piping; dilute acids <0.05 mm/year.
• Cryogenics: LNG; tough at -196°C.

Vs ASTM A 240 Gr 316H, 304L for non-chloride heat.

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9. Price of ASTM A240 Grade 304L

In November 2025, A240 Gr 304L prices range USD 3-5/kg FOB Tianjin, with hot-rolled ~$3.5/kg and cold-rolled $4.5/kg, per market trends. Ni at ~$17,000/ton influences; bulk discounts 10-15%. Gangsteel offers hedging.

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10. FAQ for ASTM A240 Grade 304L Stainless Steel Plate

Q: What is the difference between ASTM A240 304L and 304?

A: 304L has lower carbon (≤0.03% vs ≤0.08%), preventing sensitization and IGC in welds; 304 stronger but requires annealing for thick welds—304L for fabrication.

Q: Is ASTM A240 304L food grade?

A: Yes; compliant with FDA 21 CFR 177, non-reactive surface for food contact—used in dairy tanks.

Q: Can ASTM A240 304L rust?

A: Rarely in mild conditions; passive layer protects, but chlorides >200 ppm may pit—passivate per A380.

Q: Welding rod for ASTM A240 304L?

A: 308L filler; low input avoids distortion—no anneal needed.

Q: Max temp for ASTM A240 304L?

A: Continuous 870°C, intermittent 925°C; derate above 500°C.

Q: Is ASTM A240 304L magnetic?

A: Non-magnetic annealed; slight after cold work.

Q: Sizes for ASTM A240 304L plates?

A: 0.3-100 mm thick, up to 3000 mm wide; custom.

Q: 304L vs 316L corrosion?

A: 304L good for mild; 316L superior in chlorides due to Mo.

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11. Why Choose Gangsteel?

Gangsteel’s 25+ years, 500+ experts deliver E-E-A-T. 120k tons/year exports, ABS/TUV certified. For 304L: 100% PMI, custom annealing, global delivery. See ASTM A 240 Gr 316Ti.

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12. Conclusion

ASTM A240 304L is the low-carbon austenitic stainless steel for weldable, corrosion-resistant applications, its S30403 designation powering food and pharma with economy. With equivalents like EN 1.4307 and mechanics for seamless fab, at $3-5/kg in 2025, it’s versatile value. Contact Gangsteel for quotes or data on this or ASTM A 240 Gr 316H. Craft with confidence.