304H Stainless Steel Material Overview and Meaning

304H Stainless Steel: Material Overview and Meaning

At Gangsteel, a leading manufacturer and exporter of stainless steel products, we supply premium SA 240 GR 304H stainless steel plates compliant with ASME SA 240 and ASTM A240 standards. SA 240 GR 304H, also known as AISI 304H, UNS S30409, or 1.4948, is a high-carbon variant of the austenitic stainless steel 304, designed for enhanced high-temperature strength and creep resistance.

This versatile material is ideal for applications like boilers, heat exchangers, and SA 240 GR 304 pipe, where durability at elevated temperatures (up to 815°C/1500°F) is critical. This guide provides a material overview and meaning of 304H stainless steel, including its properties, specifications, and uses. For inquiries, contact us at admin@gangsteel.com or explore our ASME SA240 Stainless sheet offerings.

Overview of 304H Stainless Steel

304H stainless steel is a high-carbon austenitic stainless steel specified under ASME SA 240 for chromium and chromium-nickel stainless steel plates, sheets, and strips used in pressure vessels and high-temperature service. The "H" denotes "high carbon," with 0.04-0.10% carbon to boost creep and rupture strength at elevated temperatures compared to standard 304 (≤0.08% C) or 304L (≤0.03% C). It retains the austenitic structure, offering non-magnetic properties and a density of 8.00 g/cm³. 304H is not ideal for chloride environments but excels in high-heat applications like power generation. For related grades, see our sa240 gr 317l or sa240 gr 317.

Chemical Composition of 304H Stainless Steel

The chemical composition of 304H stainless steel enhances its high-temperature performance:

• Carbon: Higher (0.04-0.10%) than 304/304L, improving creep resistance but increasing sensitization risk during welding.
• Chromium/Nickel: Ensure corrosion resistance and non-magnetic properties.
• Comparison: Lacks molybdenum (unlike 316H) and titanium (unlike 321), limiting chloride resistance but optimizing for high-temperature strength.

Mechanical Properties of 304H Stainless Steel

The mechanical properties of 304H stainless steel for annealed plates (8-75 mm thick) support high-temperature structural use:

• High-Temperature Strength: Enhanced creep resistance; allowable stress 25.5 ksi at 1000°F vs. 18.6 ksi for 304.
• Comparison: Stronger than 304L (485 MPa tensile, 170 MPa yield) at heat but similar to 304.

Physical Properties of 304H Stainless Steel

• Density: 8.00 g/cm³, ideal for lightweight designs (e.g., 1m x 1m x 3mm plate ~24 kg).
• Melting Point: ~1400-1450°C.
• Thermal Conductivity: 16.2 W/m·K.
• Coefficient of Thermal Expansion: 17.2 × 10⁻⁶/K (20-100°C).
• Maximum Service Temperature: 1500°F (815°C) continuous; 1600°F (871°C) intermittent.

Corrosion Resistance of 304H Stainless Steel

304H stainless steel offers resistance similar to 304:

• Excellent in atmospheric, freshwater, and mild acids.
• Outperforms SS204 vs SS 304 due to high chromium/nickel.
• Sensitization risk in 797°F-1580°F (425°C-860°C) range; anneal post-weld. Less chloride-resistant than 316L.

Weldability of 304H Stainless Steel

• Fair with ER308H fillers; higher carbon increases sensitization risk, requiring controlled heat (<2.0 kJ/mm) or annealing.
• Prefer 304L for critical welds; for high-temp welds, consider 321.

Uses of 304H Stainless Steel

304H stainless steel is used in:

• Boilers/Pressure Vessels: Steam drums, headers.
• Heat Exchangers: Tubes, shells.
• Power Generation: Superheaters, reheaters.
• Chemical Processing: High-temp vessels.
• Piping: SA240 304H pipe for elevated temperatures.

For milder environments, see sa240 gr 316l or sa240 gr 316ln.

Pricing and Availability at Gangsteel

As of October 18, 2025, 304H stainless steel plate prices (2B finish, 3-6mm) range from $1.60-$3.50/kg globally. Gangsteel offers $1.60/kg FOB (MOQ 1 ton) for sa240 gr 304h plates, including custom sizes.

Why Choose Gangsteel?

Gangsteel offers certified 304H stainless steel with competitive rates and 600+ ton inventory for global delivery. Contact admin@gangsteel.com for quotes.