Grade 304H Stainless Steel: Definition and Characteristics

SS 304H material, also known as AISI 304H, UNS S30409, or 1.4948, is a high-carbon austenitic stainless steel specified under ASME SA 240 and ASTM A240 for high-temperature applications. The "304H" designation indicates a variant of 304 stainless steel with higher carbon content (0.04-0.10%) for enhanced creep and rupture strength up to 1500°F (815°C). The "H" stands for "high carbon," distinguishing it from 304 (≤0.08% C) and 304L (≤0.03% C).

It’s non-magnetic with a density of 8.00 g/cm³, ideal for boilers and heat exchangers. Gangsteel supplies premium SS 304H plates. Contact admin@gangsteel.com or visit our ASME SA240 Stainless sheet page.

What Does 304H Stand For in SS 304H Material?

The "304H" in SS 304H material stands for "high carbon," referring to its carbon content of 0.04-0.10%, which is higher than standard 304 (≤0.08% C) and 304L (≤0.03% C). Specified under ASME SA 240 as SA 240 GR 304H, this grade is designed for pressure vessels and high-temperature service, offering improved creep and stress rupture strength. The austenitic structure ensures non-magnetic properties in the annealed state, often noted as SA 240 304 non magnetic. SS 304H material is ideal for demanding applications where thermal stability is critical, unlike 304L, which prioritizes weldability. For related grades, see our sa240 gr 317l and sa240 gr 317 pages.

Chemical Composition of SS 304H Material

The chemical composition of SS 304H material enhances its high-temperature performance:

• Carbon: Higher range (0.04-0.10%) improves creep resistance but increases sensitization risk.
• Chromium: Provides corrosion resistance through a passive oxide layer.
• Nickel: Maintains the austenitic structure and non-magnetic properties.
• Comparison: Similar to 304 but with controlled carbon for heat strength. For low-carbon alternatives, see sa240 gr 316l or sa240 gr 316ln.

Mechanical Properties of SS 304H Material

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

• Tensile Strength: 515 MPa provides robust performance before fracture.
• Yield Strength: 205 MPa ensures resistance to plastic deformation.
• Elongation: 40% supports ductility for forming.
• Hardness: ≤201 HB allows good machinability.
• High-Temperature: Allowable stress 25.5 ksi at 1000°F (538°C), superior to 304L. For comparisons, see sa240 gr 201.

Physical Properties of SS 304H Material

The physical properties of SS 304H material include:

• Density: 8.00 g/cm³ for lightweight designs.
• Melting Point: ~1400-1450°C, suitable for processing.
• Thermal Conductivity: 16.2 W/m·K at 100°C.
• Coefficient of Thermal Expansion: 17.2 × 10⁻⁶/K (20-100°C).
• Electrical Resistivity: 0.72 × 10⁻⁶ Ω·m.
• Maximum Service Temperature: 1500°F (815°C) continuous; 1600°F (871°C) intermittent.

These support high-heat stability. See sa240 gr 202 for alternatives.

Corrosion Resistance of SS 304H Material

SS 304H materialresists corrosion in mild acids and atmospheres, similar to 304. Higher carbon may reduce weld zone resistance without annealing. It’s less effective against chlorides than 316L. For enhanced resistance, see sa240 gr 255.

Weldability of SS 304H Material

Weldability is fair with ER308H fillers. Higher carbon risks sensitization, requiring low heat or annealing. For better weldability, see sa240 gr 301.

Applications of SS 304H Material

SS 304H materialis used in boilers, heat exchangers, power generation, and high-temperature piping. For low-carbon alternatives, see sa240 gr 301l.

Pricing and Availability at Gangsteel

As of October 19, 2025, SS 304H material prices range from $1.60-$3.50/kg. Gangsteel offers $1.60/kg FOB (MOQ 1 ton). Contact admin@gangsteel.com.

FAQ on SS 304H Material

What is the difference between 304L and 304H stainless steel?

304L has low carbon (≤0.03%) for weldability, while 304H (0.04-0.10%) offers high-temperature strength. See sa240 gr 301ln.

What is the difference between 304 and 304H?

304 has ≤0.08% carbon for general use; 304H has higher carbon for heat resistance. See sa240 gr 305.

What is 304H material?

A high-carbon stainless steel for high-temperature service. See sa240 gr 316n.

Welding 304H stainless steel

Use ER308H fillers with annealing to avoid sensitization. See sa240 gr 316ti.

What is the carbon content of 304H?

0.04-0.10% for enhanced creep resistance. See sa240 gr 302.