What is SA 240 304H material?

What is SA 240 304H material?

When professionals in materials engineering or procurement ask, "What is SA 240 304H material?", they're typically referring to ASME SA240 Grade 304H (UNS S30409), a high-carbon austenitic stainless steel plate designed for high-temperature applications where creep resistance and strength are paramount. SA240 is the ASME specification for chromium and chromium-nickel stainless steel plate, sheet, and strip for pressure vessels and general applications, mirroring ASTM A240 in many respects. This grade modifies the standard 304 stainless steel by increasing carbon content to 0.04-0.10%, enhancing its performance in elevated temperatures up to 800°C (1472°F) while maintaining good corrosion resistance in mild environments. As a leading manufacturer and exporter in China, Gangsteel produces SA240 304H plates, sheets, and custom components, ensuring compliance with ASME SA240 and dual certification to ASTM A240 for global use.

SA240 304H is not stabilized (unlike 321H with titanium), but its controlled carbon range provides improved high-temperature tensile and creep properties, making it suitable for boilers, superheaters, and heat exchangers. It offers a PREN (Pitting Resistance Equivalent Number) of around 18-20, resisting atmospheric corrosion and dilute acids effectively. At Gangsteel, we refine 304H through argon-oxygen decarburization (AOD) for precise carbon control, delivering plates up to 100 mm thick in finishes like No.1, 2B, and polished. Priced at USD 4-6/kg in November 2025, it's a cost-effective upgrade from standard 304 for thermal duties. For related grades, explore our ASTM A 240/A 240M stainless steel plate portfolio, including ASTM A 240 Gr 304H and low-carbon ASTM A 240 Gr 304L.

Long-tail keywords: what is SA240 304H material, S30409 high carbon stainless, SA 240 Gr 304H overview, AISI 304H austenitic steel, ASME SA240 304H high temp properties

1. What is SA240 Grade 304H (S30409)?

SA240 Grade 304H is a high-carbon variant of the iconic Type 304 austenitic stainless steel, specified under ASME SA240/SA240M for chromium-nickel stainless steel plate, sheet, and strip in pressure vessels, boilers, and high-temperature service. The "H" denotes high carbon (0.04-0.10%), which promotes the formation of chromium carbides during heat treatment, pinning grain boundaries to enhance creep resistance and short-term tensile strength at temperatures above 500°C (932°F).

This makes it ideal for components like superheater tubes, furnace parts, and pressure vessel heads where sustained thermal loads could cause deformation in lower-carbon grades.

Developed as a modification of 304 to meet ASME boiler code requirements for elevated-temperature service, 304H has been a staple since the mid-20th century in power generation and petrochemical industries. At Gangsteel, we produce it from electric arc furnace melts with vacuum degassing for carbon uniformity, achieving grain size ASTM 5-7 for optimal toughness. The austenitic matrix—bolstered by 18-20% Cr and 8-10.5% Ni—provides non-magnetic properties, excellent ductility (elongation ≥40%), and formability for complex shapes. It resists scaling in air up to 800°C continuous, with a thermal conductivity of 16.2 W/m·K and expansion coefficient of 17.3 × 10⁻⁶/°C to minimize distortion.

Commonly searched as "AISI 304H plate," this grade requires careful welding (use 308H filler) and post-weld annealing at 1010-1120°C for thick sections to restore properties and prevent sensitization. Compared to ASTM A 240 Gr 304 (C ≤0.08%), 304H trades ambient weldability for superior high-temp performance. For stabilized alternatives, consider ASTM A 240 Gr 321H with titanium.

In boiler retrofits or heat treat fixtures, SA240 304H's thermal prowess often extends service life by 30-50% over standard 304, as per our client feedback from Southeast Asian refineries.

Long-tail keywords: what is SA240 Grade 304H, S30409 high carbon stainless, SA 240 Gr 304H material basics, AISI 304H austenitic overview, ASME SA240 304H creep resistance

2. SA240 Grade 304H Chemical Composition

The chemical composition of SA240 Grade 304H is engineered for high-temperature stability, compliant with ASME SA240 Table 1. Gangsteel’s production maintains carbon at 0.05-0.08% for balanced strengthening without excess sensitization risk.

High carbon fosters interstitial strengthening and carbide precipitation for creep pinning. Chromium forms the passive layer, while nickel stabilizes austenite. Low phosphorus/sulfur improve hot workability. Our lab tests show <0.1 mm scale after 1000 hours at 700°C in air.

Note: Unlike ASTM A 240 Gr 316H, no molybdenum—lower PREN but sufficient for non-chloride heat. MTRs include full analysis.

Long-tail keywords: SA240 Grade 304H chemical composition, S30409 alloy elements, SA 240 Gr 304H chemistry, AISI 304H high carbon formula, ASME SA240 304H Cr Ni content

3. SA240 Grade 304H Mechanical Properties

Mechanical properties of SA240 Grade 304H prioritize elevated-temperature endurance, tested per ASME SA240 (aligned with ASTM E8).

High carbon retains >60% strength at 600°C, with creep rates <0.1%/1000h. Fatigue 200 MPa at 10^7 cycles annealed.

Compared to ASTM A 240 Gr 304L, 304H edges in yield (205 vs 170 MPa) and heat performance. Machinability 40% of B1112; cold-form to 180°.

Long-tail keywords: SA240 Grade 304H mechanical properties, S30409 tensile yield, SA 240 Gr 304H elongation hardness, AISI 304H creep data, ASME SA240 304H high temp strength

4. SA240 Grade 304H Allowable Stress

Allowable stresses per ASME BPVC Section II Part D Table 1A ensure safe operation.

High carbon supports higher stresses than 304L at >500°C. For hotter, consider stabilized ASTM A 240 Gr 321H. Certs include tables.

Long-tail keywords: SA240 Grade 304H allowable stress, S30409 ASME values, SA 240 Gr 304H design stress, AISI 304H temperature derating, ASME SA240 304H pressure limits

5. SA240 Grade 304H Equivalent Materials

Equivalents for SA240 304H enable global sourcing, with detailed specs.

These match high C for creep; EN 1.4948 has similar Ni. Gangsteel dual-certs for ASME/EN.

Long-tail keywords: SA240 Grade 304H equivalents, S30409 international grades, SA 240 Gr 304H standards match, AISI 304H DIN EN JIS, ASME SA240 304H global substitutes

6. SA240 Grade 304H vs SA 240 Gr 304, SA 240 Gr 304L, and SA 240 Gr 321H

Trade-offs guide selection vs ASTM A 240 Gr 304, ASTM A 240 Gr 304L, ASTM A 240 Gr 321H.

• 304H vs 304: 304H’s high C boosts creep 50% at hot temps; same corrosion, but 304H for sustained heat.
• 304H vs 304L: 304L’s low C excels in welds (no anneal); 304H stronger for non-weld thermal.
• 304H vs 321H: 321H’s Ti stabilizes against IGC in heat; 304H simpler/cheaper for non-sensitizing conditions.

Choose 304H for high-temp strength, 304 ambient, 304L welds, 321H stabilized heat.

Long-tail keywords: SA240 Grade 304H vs 304, 304H vs 304L comparison, SA 240 Gr 304H vs 321H, AISI 304H alternatives, ASME SA240 304H grade differences

7. SA240 Grade 304H Specifications

Gangsteel supplies 304H in forms with ±0.1 mm tolerances.

7.1 Plate and Sheet

• Thickness: 3-100 mm (plate), 0.5-6 mm (sheet)
• Width: 1000-2500 mm
• Length: 2000-12000 mm/coils
• Surface: No.1, 2B, annealed
• Standards: ASME SA240, ASTM A240, AMS 5512
• Uses: Plates for heads, sheets for ducting

7.2 Bar and Rod

• Diameter: 6-300 mm
• Length: Up to 6000 mm
• Finish: Hot-rolled, peeled
• Standards: ASME SA479, ASTM A276
• Uses: Shafts, valves

7.3 Custom Components

• Types: Flanges, fittings
• Processes: Machined, welded
• Certs: EN 10204 3.2, NACE
• Uses: Bespoke for boilers

Stock: 500 tons; 10-15 days lead.

Long-tail keywords: SA240 Grade 304H plate specs, S30409 sheet dimensions, SA 240 Gr 304H bar sizes, AISI 304H custom parts, ASME SA240 304H finishes

8. Applications of SA240 Grade 304H

304H thrives in high-temp non-corrosive:

• Power Generation: Boiler tubes; retains strength to 700°C.
• Petrochemical: Reformers; creep resistant.
• Heat Treatment: Fixtures; cyclic tolerant.
• Chemical: Heat exchangers; oxidizing acids.
• Aerospace: Engine parts; thermal fatigue.

Vs ASTM A 240 Gr 316H, 304H for dry without chlorides.

Long-tail keywords: SA240 Grade 304H applications, S30409 industrial uses, SA 240 Gr 304H in power, AISI 304H petrochemical, ASME SA240 304H heat exchangers

9. Price of SA240 Grade 304H

November 2025 prices: USD 4-6/kg FOB, with hot-rolled ~$4.5/kg, per market data. Ni ~$17k/ton influences; high C adds 10-20% over 304. Gangsteel discounts bulk.

Long-tail keywords: SA240 Grade 304H price per kg 2025, S30409 cost, SA 240 Gr 304H market rate, AISI 304H pricing, ASME SA240 304H bulk

10. FAQ for SA240 Grade 304H Stainless Steel Plate

Q: What is the difference between SA240 304H and 304?

A: SA240 304H has higher carbon (0.04-0.10% vs ≤0.08%), improving high-temperature strength and creep resistance for applications above 500°C, while standard 304 is better for ambient weldability without annealing needs.

Q: Is SA240 304H suitable for high temperatures?

A: Yes; optimized for 500-800°C with creep rupture >150 MPa at 650°C/10,000 hours—used in boilers and superheaters.

Q: What welding rod for SA240 304H?

A: 308H filler; low input; post-anneal at 1010-1120°C for thick sections to restore properties.

Q: Can SA240 304H resist corrosion?

A: Good in mild acids/atmospheres (<0.1 mm/year in 10% HNO3); not for chlorides—PREN 19.

Q: Is SA240 304H magnetic?

A: Non-magnetic annealed; slight after cold work—anneal to restore.

Q: Sizes for SA240 304H plates?

A: 3-100 mm thick, up to 2500 mm wide; custom.

Q: 304H vs 316H corrosion/strength?

A: Similar strength; 316H’s Mo better for chlorides (PREN 25 vs 19)—304H for dry heat.

Long-tail keywords: SA240 304H FAQ, S30409 questions, SA 240 Gr 304H vs 304, AISI 304H temp limits, ASME SA240 304H welding

11. Why Choose Gangsteel?

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

Long-tail keywords: SA240 304H supplier China, S30409 exporter Gangsteel, SA 240 Gr 304H quality, AISI 304H source, ASME SA240 304H Gangsteel

12. Conclusion

SA 240 304H material is ASME SA240 Grade 304H, the high-carbon austenitic stainless for high-temp strength in boilers and reformers. With equivalents like EN 1.4948 and mechanics for enduring heat, at $4-6/kg in 2025, it’s thermal value. Contact Gangsteel for quotes or data on this or ASTM A 240 Gr 304LN. Engineer with excellence.