A 240 304H Stainless Steel Chemical Composition Detailed Ana

A 240 304H Stainless Steel Chemical Composition: Detailed Analysis

At Gangsteel, a leading manufacturer and exporter of stainless steel products, we supply high-quality A 240 304H stainless steel plates compliant with ASTM A240 and ASME SA 240 standards. A 240 304H stainless steel, also known as AISI 304H, UNS S30409, or EN 1.4948, is a high-carbon austenitic stainless steel optimized for high-temperature strength and creep resistance up to 1500°F (815°C). This guide provides a detailed analysis of the chemical composition of A 240 304H stainless steel, including the role of each element in its properties and performance for applications 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 of A 240 304H Stainless Steel

The chemical composition of A 240 304H stainless steel, as per ASTM A240 and ASME SA 240, is tailored for high-temperature corrosion and strength:

This composition balances strength, corrosion resistance, and formability. See sa240 gr 304h.

Detailed Examination of Key Elements

Carbon (0.04 - 0.10%)

Carbon is the defining feature of A 240 304H stainless steel, higher than 304 (≤0.08%) and 304L (≤0.03%). It enhances creep and stress rupture strength at elevated temperatures (e.g., 25.5 ksi allowable stress at 1000°F/538°C vs. 18.6 ksi for 304). However, it increases the risk of sensitization (carbide precipitation) in the 797°F-1580°F (425°C-860°C) range during welding, potentially depleting chromium and reducing corrosion resistance unless annealed.

Chromium (18.00 - 20.00%)

Chromium forms a passive oxide layer, providing excellent corrosion resistance in mild acids, freshwater, and atmospheric conditions, outperforming SS204 vs SS 304. At 18-20%, it supports scaling resistance up to 1200°F (649°C), critical for high-temperature applications like boilers.

Nickel (8.00 - 10.50%)

Nickel stabilizes the austenitic structure, ensuring A 240 304H stainless steel remains non-magnetic (SA 240 304 non magnetic) in the annealed state. It enhances ductility (40% elongation) and formability, allowing easy shaping for components like plat SS 304 3mm or plate 2 mm SUS 304.

Manganese (0.00 - 2.00%)

Manganese improves hardenability and toughness, stabilizing the austenitic structure and aiding deoxidation during production. It has minimal impact on corrosion but supports mechanical stability at high temperatures.

Silicon (0.00 - 0.75%)

Silicon enhances scaling and oxidation resistance at elevated temperatures, crucial for 304H's service up to 1500°F (815°C). It also aids in deoxidation, improving weldability and surface quality.

Phosphorus and Sulfur (0.00 - 0.045% P, 0.00 - 0.030% S)

Phosphorus and sulfur are limited to minimize embrittlement and improve weld quality. Low levels prevent cracking and support formability without compromising strength.

Nitrogen (0.00 - 0.10%)

Nitrogen strengthens the alloy, enhancing creep resistance and stabilizing austenite. It contributes to corrosion resistance in neutral environments.

Iron (Balance)

Iron is the base metal, providing the structural framework that, combined with alloying elements, yields the 8.00 g/cm³ density and overall durability.

Mechanical Properties

High-temperature strength: Allowable stress 25.5 ksi at 1000°F (538°C).

Physical Properties

• Density: 8.00 g/cm³.
• Melting Point: 1400-1450°C.
• Thermal Conductivity: 16.2 W/m·K.
• Coefficient of Thermal Expansion: 17.2 × 10⁻⁶/K.
• Max Service Temperature: 1500°F (815°C) continuous.

Corrosion Resistance

A240 304H stainless steel resists mild acids and atmospheric conditions, outperforming SS204 vs SS 304. Higher carbon risks sensitization in welds; anneal for protection. See sa240 gr 316l for chlorides.

Weldability

Fair with ER308H fillers; low heat input (<2.0 kJ/mm) and annealing required. See sa240 gr 321.

Applications

A240 304H stainless steel is used in:

• Boilers and pressure vessels.
• Heat exchangers.
• Power generation piping.
• High-temperature chemical processing.

For cost-effective options, see sa240 gr 201.

Pricing and Availability

As of October 19, 2025, A240 304H stainless steel plate prices (2B finish, 3-6mm) range from $1.60-$3.50/kg. Gangsteel offers $1.60/kg FOB (MOQ 1 ton) for sa240 gr 304h. Contact admin@gangsteel.com or visit astm a 240 stainless plate.

FAQ on A240 304H Stainless Steel Chemical Composition

What is the carbon content of A240 304H stainless steel?

0.04-0.10%, higher than 304 (≤0.08%) and 304L (≤0.03%), for enhanced creep resistance.

How does chromium contribute to A240 304H stainless steel?

Chromium (18-20%) forms a passive oxide layer for corrosion resistance in mild acids and atmospheric conditions.

Why is nickel important in A240 304H stainless steel?

Nickel (8-10.5%) stabilizes the austenitic structure, ensuring non-magnetic properties (SA 240 304 non magnetic) and formability.

How does 304H compare to 304L in chemical composition?

304H has higher carbon (0.04-0.10% vs. ≤0.03%) for high-temperature strength, while 304L prioritizes weldability.

What applications benefit from A240 304H’s chemical composition?

The high carbon and chromium/nickel content make it ideal for boilers, heat exchangers, and piping requiring creep resistance up to 1500°F.