what is the difference between 304l and 304h stainless steel

Difference Between 304L and 304H Stainless Steel: A Detailed Comparison

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

Both are austenitic with similar chromium (18-20%) and nickel (8-10.5%) content, but their carbon levels drive key differences in applications like plat stainless 304 and SA 240 GR 304 pipe.

This article compares 304L and 304H in terms of chemical composition, mechanical properties, corrosion resistance, weldability, cost, and applications. For inquiries, contact us at admin@gangsteel.com or explore our ASME SA 240 stainless steel plate offerings.

Overview of 304L vs. 304H Stainless Steel

• 304L: Low-carbon (≤0.03%) version of 304, prioritizing weldability and corrosion resistance in welded structures. Ideal for food processing, chemical tanks, and general fabrication.
• 304H: High-carbon (0.04-0.10%) version of 304, optimized for elevated-temperature service (up to 815°C/1500°F) with improved creep and rupture strength. Suitable for boilers, heat exchangers, and power generation components.

Both grades are non-magnetic in the annealed state (SA 240 304 non magnetic) and have a density of 8.00 g/cm³, but 304H trades some weldability for high-temperature performance.

Chemical Composition Comparison

The primary difference is carbon content, with 304H having higher levels for strength at heat:

• Carbon: 304L’s low carbon minimizes sensitization (carbide precipitation) during welding, while 304H’s higher carbon boosts high-temperature strength.
• Nickel/Chromium: Identical, ensuring similar corrosion resistance and ductility.

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

Mechanical Properties Comparison

• Strength: 304H’s higher carbon provides better tensile (515 MPa) and yield strength (205 MPa) than 304L (485 MPa, 170 MPa), especially at elevated temperatures (e.g., allowable stress 25.5 ksi at 1000°F vs. 14.9 ksi for 304L).
• Ductility: Both offer ≥40% elongation, ideal for forming (e.g., plat SS 304 3mm).

Corrosion Resistance Comparison

Both grades offer excellent corrosion resistance in mild environments:

• Atmospheric conditions, freshwater, and mild acids (food-grade).
• Outperform SS204 vs SS 304 due to high chromium and nickel.

Key differences:

• 304L: Superior in welded applications, as low carbon prevents sensitization, maintaining corrosion resistance in weld zones.
• 304H: Similar to 304 in mild environments but higher carbon increases sensitization risk during welding, potentially reducing corrosion resistance unless annealed. Less suitable for chlorides than SA 240 GR 316L.

For chloride-heavy environments, explore sa 240 gr 316l.

Weldability Comparison

• 304L: Excellent weldability due to low carbon (≤0.03%), minimizing sensitization. Uses ER308L fillers; ideal for welded SA 240 GR 304 pipe.
• 304H: Fair weldability with ER308H fillers, but higher carbon (0.04-0.10%) raises sensitization risk, requiring controlled heat input (<2.0 kJ/mm) or post-weld annealing. Less forgiving than 304L.

Cost Comparison

As of October 15, 2025:

Gangsteel offers 304L at $1.50/kg FOB and 304H at $1.60/kg FOB (MOQ 1 ton). Contact admin@gangsteel.com for quotes.

Applications

• 304L: Food processing (tanks, plat stainless 304), chemical equipment, architecture (plate 2 mm SUS 304), welded structures. See sa 240 gr 304l.
• 304H: Boilers, heat exchangers, high-temperature piping requiring creep resistance. See sa 240 gr 304h.

For high-temperature stability, explore sa 240 gr 321.

Which is Better?

• Choose 304Lfor weldability and corrosion resistance in mild environments (e.g., food-grade, chemical).
• Choose 304Hfor high-temperature strength in boilers and heat exchangers, accepting reduced weldability.

Why Choose Gangsteel?

Gangsteel provides certified SA 240 GR 304L and 304H plates with competitive SS 304 plate price starting at $1.50/kg FOB for 304L. Our 600+ ton inventory supports global delivery for applications from plat stainless 304 to heavy plates. For quotes or to learn more, visit our astm a 240 stainless plate page or email admin@gangsteel.com.