304H Stainless Steel Properties Mechanical and Physical

304H Stainless Steel Properties: Mechanical and Physical

At Gangsteel, a leading manufacturer and exporter of stainless steel products, we supply premium 304H stainless steel plates compliant with ASME SA 240 and ASTM A240 standards. 304H stainless steel, also known as AISI 304H, UNS S30409, or EN 1.4948, is a high-carbon variant of 304, optimized for high-temperature strength and creep resistance up to 1500°F (815°C). This guide details the mechanical and physical properties of 304H stainless steel for applications like boilers, heat exchangers, and SA 240 GR 304 pipe. For inquiries, contact us at admin@gangsteel.com or explore our ASME SA240 Stainless sheet offerings.

Mechanical Properties of 304H Stainless Steel

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

• High-Temperature Strength: Higher carbon (0.04-0.10%) provides superior creep resistance, with allowable stress of 25.5 ksi at 1000°F (538°C) vs. 18.6 ksi for 304 and 14.9 ksi for 304L, per ASME BPVC Section II, Part D.
• Cold-Working: Can increase tensile strength up to 900 MPa, reducing ductility.
• Comparison: Stronger than sa240 gr 304l but similar to sa240 gr 304 at room temperature, with enhanced high-temperature performance.

Physical Properties of 304H Stainless Steel

The physical properties of 304H stainless steel ensure suitability for high-temperature environments:

• Density: 8.00 g/cm³, ideal for lightweight designs (e.g., a 1m x 1m x 3mm plate weighs ~24 kg).
• Melting Point: 1400-1450°C, supporting high-temperature processing.
• Thermal Conductivity: 16.2 W/m·K at 100°C, moderate for heat transfer.
• Coefficient of Thermal Expansion: 17.2 × 10⁻⁶/K (20-100°C), stable across temperatures.
• Electrical Resistivity: 0.72 × 10⁻⁶ Ω·m, suitable for non-conductive applications.
• Service Temperature:
  • Continuous: Up to 1500°F (815°C), with excellent creep resistance.
  • Intermittent: Up to 1600°F (871°C) for short-term exposure.
  • Scaling Onset: ~1200°F (649°C), accelerating above 1500°F.
  • Sensitization Range: Avoid 797°F-1580°F (425°C-860°C) to prevent carbide precipitation.

These properties make 304H stainless steel ideal for high-heat applications, unlike ferritic grades like sa240 gr 430.

Corrosion Resistance

304H stainless steeloffers corrosion resistance similar to 304:

• Excellent in atmospheric conditions, freshwater, and mild acids (food-grade).
• Outperforms SS204 vs SS 304 due to higher nickel (8-10.5%).
• Higher carbon increases sensitization risk in weld zones (797°F-1580°F), requiring annealing. Less chloride-resistant than sa240 gr 316l.

Weldability

Weldability is fair using ER308H fillers. Higher carbon (0.04-0.10%) risks sensitization, necessitating low heat input (<2.0 kJ/mm) or post-weld annealing (1870-2100°F). For better weldability, see sa240 gr 304l or sa240 gr 321.

Applications

304H stainless steelis used in:

• Boilers and pressure vessels (steam drums, headers).
• Heat exchangers (tubes, shells).
• Power generation (superheaters, reheaters).
• Chemical processing (vessels, SA 240 GR 304 pipe).
• High-temperature piping and fittings.

For chloride-heavy environments, explore sa240 gr 317l.

Pricing and Availability

As of October 19, 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 like plate 2 mm SUS 304. Contact admin@gangsteel.com or visit astm a 240 stainless plate.

FAQ on 304H Stainless Steel Properties

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

304 has ≤0.08% carbon for general use, while 304H (0.04-0.10% C) offers higher creep strength for temperatures up to 1500°F. 304H is less weldable due to sensitization risks.

How does 304H compare to 304L in mechanical properties?

304H has higher tensile (515 MPa) and yield strength (205 MPa) than 304L (485 MPa, 170 MPa), especially at high temperatures, due to increased carbon content.

What is the maximum service temperature for 304H stainless steel?

Continuous service up to 1500°F (815°C); intermittent up to 1600°F (871°C). Scaling begins at ~1200°F.

Why is 304H stainless steel non-magnetic?

Its austenitic structure, stabilized by 8-10.5% nickel, ensures non-magnetic properties in the annealed state, ideal for applications like medical devices.

What are the main applications of 304H stainless steel?

Used in boilers, heat exchangers, and high-temperature piping, leveraging its creep resistance for reliable performance in power generation and chemical processing.