ASME SA240 347H Stainless Steel Plate | SA240 Type 347H

As a professional stainless steel plate supplier and China Mill-Direct Supply / Mill Direct Exporter, SHH STEEL is pleased to present ASME SA240 347H Stainless Steel Plate, also known as SA240 Type 347H.

ASME SA240 Type 347H is the higher-carbon version of the niobium-stabilized austenitic stainless steel Type 347. While standard Type 347 has a maximum carbon content of 0.08%, Type 347H is deliberately specified with a carbon range of 0.04–0.10%. This controlled higher carbon content provides significantly improved strength at elevated temperatures, particularly above 500°C, while the niobium stabilization continues to deliver outstanding resistance to intergranular corrosion after welding or after prolonged exposure to the sensitization temperature range.

Type 347H combines the high-temperature strength advantage of the “H” grades with the superior long-term stability of niobium stabilization. It is widely selected for pressure vessels, boilers, heat exchangers, superheater components, and high-temperature process equipment that operate continuously at elevated temperatures and require reliable resistance to sensitization.

SHH STEEL supplies ASME SA240 347H as true Mill Direct Supply, sourcing directly from major Chinese stainless steel mills. This model delivers competitive mill pricing, consistent quality, full heat traceability, and shorter lead times. We offer thicknesses from 3 mm to 100 mm (thicker plates available on request), widths up to 2000–3000 mm, and lengths up to 12000 mm or cut-to-length. Material is supplied in the solution-annealed condition, most commonly with No.1 finish for pressure vessel applications.

Heat Analysis (Ladle Analysis) according to ASME SA240 Type 347H:

Product Analysis (typical permissible variations):

The controlled carbon range of 0.04–0.10% provides the necessary solid-solution strengthening and improved creep strength at elevated temperatures, while the minimum niobium content of eight times the carbon percentage ensures effective stabilization against intergranular corrosion.

Room-Temperature Mechanical Properties (Annealed Condition)

Elevated-Temperature Performance ASME SA240 347H is specifically intended for service at elevated temperatures. The higher carbon content delivers better tensile and yield strength above approximately 500°C and improved long-term creep and stress-rupture properties compared with standard Type 347. It is commonly used in the temperature range where higher ASME allowable stresses are required.

Physical Properties

• Density: 7.93 g/cm³
• Melting Range: approximately 1400–1425°C
• Magnetic: Non-magnetic in the annealed condition

When both elevated-temperature strength and the highest level of long-term stability are required, ASME SA240 347H is the preferred stabilized “H” grade. It offers better high-temperature performance than standard astm a240 type 347 stainless steel sheet plate while retaining excellent resistance to intergranular corrosion. For applications that also require improved chloride resistance, astm a240 type 316ti stainless steel sheet plate may be considered. For general high-temperature service without the need for stabilization, astm a240 type 304h stainless steel sheet plate remains a more economical option.

High-Temperature Performance and Sensitization

The higher carbon content that gives Type 347H its elevated-temperature strength is effectively controlled by niobium stabilization. Niobium combines preferentially with carbon, greatly reducing the risk of chromium carbide precipitation even during prolonged exposure in the temperature range of 450–850°C. This makes Type 347H particularly suitable for continuous high-temperature service where both mechanical strength and long-term microstructural stability are required.

In the properly annealed condition, ASME SA240 Type 347H offers corrosion resistance similar to Type 347 and Type 304 in most atmospheric, fresh-water, and oxidizing environments. Its principal advantage is the excellent resistance to intergranular corrosion after welding or after prolonged high-temperature exposure, thanks to niobium stabilization.

Resistance to pitting and crevice corrosion in chloride environments is comparable to 304 and inferior to molybdenum-bearing grades. For combined high-temperature and chloride service, a molybdenum-containing stabilized grade such as 316Ti is often preferred.

ASME SA240 Type 347H can be welded by all standard fusion and resistance welding methods. Matching niobium-stabilized filler metals (E347 / ER347) are recommended to maintain stabilization and high-temperature strength in the weld metal.

Because of the niobium stabilization, the grade can normally be used in the as-welded condition without risk of intergranular corrosion. When maximum high-temperature strength of the weld is required, high-carbon matching consumables are preferred.

ASME SA240 Type 347H is supplied in the solution-annealed condition. Proper heat treatment is essential to achieve optimum properties.

Recommended Solution Annealing Parameters

• Temperature range: 1040 – 1150°C (typically 1050 – 1120°C)
• Holding (soaking) time: – Plates ≤ 25 mm thick: minimum 10–20 minutes after the entire cross-section has reached the target temperature – Plates 25–50 mm thick: minimum 20–40 minutes – Plates above 50 mm: 30–60 minutes or longer, depending on thickness and furnace loading, to ensure uniform temperature
• Cooling: Rapid cooling is mandatory. Water quenching is strongly preferred for thicker plates to retain the stabilized structure, maximize corrosion resistance, and preserve high-temperature strength capability.

An optional stabilizing treatment at approximately 840–900°C may be applied in special cases to ensure complete niobium carbide precipitation, although modern production practices usually make this unnecessary for most applications.

SHH STEEL regularly supplies ASME SA240 347H in No.1 finish for pressure vessel applications and can provide other finishes according to project requirements.

Dimensional tolerances for ASME SA240 347H plate follow ASME SA240 and the referenced ASTM A480 requirements. Thickness, width, length, and flatness are controlled within standard limits. Tighter tolerances can be arranged for specific projects.

Related grades frequently evaluated with ASME SA240 347H include astm a240 type 347 stainless steel sheet plate, astm a240 type 321 stainless steel sheet plate, astm a240 type 304h stainless steel sheet plate, and astm a240 type 316ti stainless steel sheet plate.

ASME SA240 Type 347H is selected for equipment that requires both elevated-temperature strength and long-term resistance to sensitization:

SHH STEEL is a China Mill-Direct Supply and Mill Direct Exporter of stainless steel plate. We maintain long-term strategic relationships with major Chinese stainless steel mills and supply ASME SA240 Type 347H with the following advantages:

• Competitive mill-direct pricing
• Consistent quality and complete heat traceability
• Full Mill Test Certificates (EN 10204 3.1 / ASME)
• Flexible thickness, width, and length combinations
• Technical assistance on high-temperature material selection
• Reliable worldwide logistics and export documentation

ASME SA240 347H Stainless Steel Plate (SA240 Type 347H) is the high-carbon niobium-stabilized austenitic grade optimized for elevated-temperature strength while retaining excellent resistance to intergranular corrosion. It is the material of choice when design conditions demand higher allowable stresses at temperature together with the superior long-term stability of niobium stabilization.

As a professional China Mill-Direct Supply and Mill Direct Exporter, SHH STEEL provides reliable ASME SA240 Type 347H plate with competitive pricing, full certification, and complete technical support.

Contact SHH STEEL today for stock availability, surface finish options (including SA240 347H No.1 and SA240 347H 2B), or a competitive quotation for your high-temperature stainless steel requirements.

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