304H Mechanical Properties Yield Strength and Elongation

304H Mechanical Properties: Yield Strength and Elongation

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 austenitic stainless steel designed for enhanced high-temperature strength and creep resistance up to 1500°F (815°C). This guide focuses on the yield strength and elongation of 304H stainless steel, alongside other mechanical properties, 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.

Yield Strength of 304H Stainless Steel

The yield strength of 304H stainless steel is the stress at which plastic deformation begins (0.2% offset). For annealed plates (8-75 mm thick), the minimum yield strength is:

• Yield Strength: 205 MPa (30 ksi)

This value is higher than SA 240 GR 304L (170 MPa) and matches SA 240 GR 304, reflecting the strengthening effect of higher carbon content (0.04-0.10%). At elevated temperatures, 304H stainless steel maintains superior creep resistance, with an allowable stress of 25.5 ksi at 1000°F (538°C) compared to 14.9 ksi for 304L, per ASME BPVC Section II, Part D. This makes it ideal for high-temperature structural applications like sa240 gr 304h plates in boilers.

Elongation of 304H Stainless Steel

The elongation of 304H stainless steel measures its ductility, or ability to deform before fracturing. For annealed plates, the minimum elongation is:

• Elongation (A5, 50 mm): 40%

This high ductility (≥40%) matches 304 and 304L, enabling excellent formability for applications like plat SS 304 3mm and plate 2 mm SUS 304. It supports complex shaping in high-temperature components without cracking, ensuring reliability in fabrication processes.

Other Mechanical Properties

Additional mechanical properties of 304H stainless steel include:

• Tensile Strength: 515 MPa ensures robust performance, comparable to 304 but higher than 304L.
• Hardness: ≤201 HB allows easy machining and forming, similar to sa240 gr 304.
• Cold-Working: Can increase strength (e.g., tensile up to 900 MPa), reducing elongation for high-strength needs.

Physical Properties Supporting Mechanical Performance

The physical properties of 304H stainless steel complement its mechanical properties:

• 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, suitable for high-temperature processing.
• Thermal Conductivity: 16.2 W/m·K at 100°C.
• Coefficient of Thermal Expansion: 17.2 × 10⁻⁶/K (20-100°C).
• Service Temperature: Continuous up to 1500°F (815°C); intermittent up to 1600°F (871°C).

These properties enhance the yield strength and elongation performance in high-heat environments, 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 (0.04-0.10%) 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 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 Leveraging Yield Strength and Elongation

304H stainless steelis used in:

• Boilers and pressure vessels, leveraging high yield strength for structural integrity.
• Heat exchangers, utilizing elongation for forming complex shapes.
• Power generation (superheaters, reheaters).
• Chemical processing (vessels, SA 240 GR 304 pipe).
• High-temperature piping and fittings, benefiting from creep resistance.

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

Pricing and Availability at Gangsteel

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. Contact admin@gangsteel.com or visit astm a 240 stainless plate.

FAQ on 304H Stainless Steel Mechanical Properties

What is the yield strength of 304H stainless steel?

The minimum yield strength is 205 MPa (30 ksi), higher than 304L (170 MPa), ensuring better resistance to deformation at high temperatures.

What is the elongation of 304H stainless steel?

Minimum elongation is 40% (A5, 50 mm), providing excellent ductility for forming complex shapes in applications like heat exchangers.

How does 304H compare to 304L in yield strength and elongation?

304H has higher yield strength (205 MPa vs. 170 MPa) due to increased carbon, with identical elongation (40%), but 304L is better for weldability.

Why is 304H stainless steel suitable for high-temperature applications?

High yield strength (205 MPa) and creep resistance (25.5 ksi at 1000°F) make it ideal for boilers and piping under thermal stress.

What applications leverage 304H yield strength and elongation?

Boilers, heat exchangers, and SA 240 GR 304 pipe benefit from high yield strength for load-bearing and elongation for formability. See sa240 gr 316ln.