304L vs 304H Stainless Steel Key Differences and Uses

304L vs 304H Stainless Steel: Key Differences and Uses

At Gangsteel, a leading manufacturer and exporter of stainless steel products, we supply premium SA 240 GR 304L and SA 240 GR 304H plates compliant with ASME SA 240 and ASTM A240 standards. 304L stainless steel (UNS S30403, AISI 304L, EN 1.4306/1.4307) is a low-carbon austenitic stainless steel optimized for weldability and corrosion resistance in mild environments. 304H stainless steel (UNS S30409, AISI 304H, EN 1.4948) is a high-carbon variant designed for enhanced high-temperature strength and creep resistance up to 1500°F (815°C).

Both grades are non-magnetic (SA 240 304 non magnetic) with a density of 8.00 g/cm³. This guide compares 304L vs 304H stainless steel in terms of chemical composition, mechanical properties, corrosion resistance, weldability, cost, and applications for uses like plat stainless 304 and SA 240 GR 304 pipe. For inquiries, contact us at admin@gangsteel.com or explore our ASME SA240 Stainless sheet offerings.

Chemical Composition Comparison

The chemical composition is the primary differentiator, with carbon content driving key performance differences:

• Carbon: 304L’s low carbon (≤0.03%) prevents chromium carbide precipitation during welding, ensuring corrosion resistance in weld zones. 304H’s higher carbon (0.04-0.10%) boosts creep and stress rupture strength at elevated temperatures (e.g., 25.5 ksi at 1000°F vs. 14.9 ksi for 304L).
• Chromium/Nickel: Identical ranges provide similar corrosion resistance in mild environments, outperforming SS204 vs SS 304 due to higher nickel.
• Comparison: 304L lacks the high-temperature strength of 304H, while 304H sacrifices some weldability. For chloride resistance, see sa240 gr 316l.

For detailed specifications, refer to our SS 304 data sheet.

Mechanical Properties Comparison

The mechanical properties of 304L and 304H stainless steel for annealed plates (8-75 mm thick) reflect their distinct design purposes:

• Tensile Strength: 304H’s 515 MPa outperforms 304L’s 485 MPa, particularly at elevated temperatures, with an allowable stress of 25.5 ksi at 1000°F (538°C) vs. 14.9 ksi for 304L, per ASME BPVC Section II, Part D.
• Yield Strength: 304H’s 205 MPa provides better load-bearing capacity than 304L’s 170 MPa, especially in high-temperature environments like boilers.
• Elongation: Both grades offer 40% elongation, ensuring excellent formability for applications like plate 2 mm SUS 304.
• Hardness: Identical hardness (≤201 HB, ≤92 HRB) supports machining and forming, with 304H maintaining stability at high temperatures.
• Cold-Working: Both can increase strength (e.g., tensile up to 900 MPa) with reduced ductility, but 304H’s higher carbon enhances high-temperature performance.

For comparison with other grades, see sa240 gr 304 and sa240 gr 304h.

Corrosion Resistance Comparison

Both 304L and 304H stainless steel offer excellent corrosion resistance in:

• Atmospheric conditions, freshwater, and mild acids (food-grade environments).
• General settings, outperforming SS204 vs SS 304 due to higher nickel content (8-12% for 304L, 8-10.5% for 304H).

Key Differences:

• 304L: Low carbon (≤0.03%) minimizes sensitization (chromium carbide precipitation) during welding, maintaining corrosion resistance in weld zones, making it ideal for welded structures like SA 240 GR 304 pipe.
• 304H: Higher carbon (0.04-0.10%) increases sensitization risk in the 797°F-1580°F (425°C-860°C) range during welding or service, potentially reducing corrosion resistance in weld zones unless annealed post-weld (1870-2050°F).

Both grades are less resistant to chloride-induced pitting compared to molybdenum-enhanced grades like sa240 gr 317l.

Weldability Comparison

• 304L: Excellent weldability using ER308L fillers. Low carbon content minimizes sensitization, eliminating the need for post-weld annealing in most cases, ideal for welded applications like chemical tanks and piping.
• 304H: Fair weldability using ER308H fillers. Higher carbon increases sensitization risk, requiring controlled heat input (<2.0 kJ/mm) or post-weld annealing (1870-2050°F) to restore corrosion resistance. For high-temperature welds, consider sa240 gr 321.

Physical Properties Comparison

Both grades share identical physical properties due to similar compositions:

• 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 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.
• Service Temperature:
  • 304L: Continuous up to ~800°F (427°C), suitable for mild environments.
  • 304H: Continuous up to 1500°F (815°C); intermittent up to 1600°F (871°C), with scaling onset at ~1200°F (649°C).

These properties support 304H’s high-temperature applications and 304L’s weldability. For cost-effective alternatives, see sa240 gr 201.

Cost Comparison

As of October 19, 2025:

Gangsteel offers competitive pricing: $1.50/kg FOB for 304L and $1.60/kg FOB for 304H (MOQ 1 ton). Contact admin@gangsteel.com or visit sa240 gr 304h.

Applications of 304L vs 304H Stainless Steel

• 304L: Ideal for welded applications in mild environments, including:
  • Food processing (tanks, conveyors, plat stainless 304).
  • Chemical equipment (vessels, SA 240 GR 304 pipe).
  • Architecture (plate 2 mm SUS 304, decorative panels).
  • Medical devices (non-magnetic components).
    See sa240 gr 304l.
• 304H: Suited for high-temperature applications, including:
  • Boilers and pressure vessels (steam drums, headers).
  • Heat exchangers (tubes, shells).
  • Power generation (superheaters, reheaters).
  • High-temperature piping and fittings.
    See sa240 gr 304h.

For high-temperature stability or chloride resistance, explore sa240 gr 321 or sa240 gr 316l.

Which is Better?

• Choose 304Lfor welded applications in mild environments (e.g., food processing, chemical tanks) where corrosion resistance and ease of welding are priorities.
• Choose 304Hfor high-temperature applications (e.g., boilers, heat exchangers) requiring creep resistance and strength up to 1500°F, despite reduced weldability.

Summary

304L stainless steelexcels in weldability and corrosion resistance in mild environments due to its low carbon content (≤0.03%), making it ideal for food processing and chemical applications.

304H stainless steel, with higher carbon (0.04-0.10%), offers superior tensile (515 MPa) and yield strength (205 MPa) at high temperatures (up to 1500°F), suited for boilers and power generation, but requires annealing to mitigate sensitization risks during welding.

Both share similar corrosion resistance and physical properties, but 304L is better for welds, while 304H is designed for heat. Gangsteel offers both at competitive prices ($1.50/kg for 304L, $1.60/kg for 304H FOB). Contact admin@gangsteel.com or visit astm a 240 stainless plate for quotes.