ASME SA240 347 Stainless Steel Plate | SA240 Type 347
What is ASME SA240 347 Stainless Steel Plate?
As a professional stainless steel plate supplier and China Mill-Direct Supply / Mill Direct Exporter, SHH STEEL is pleased to present ASME SA240 347 Stainless Steel Plate, also known as SA240 Type 347.
ASME SA240 Type 347 is a niobium (columbium)-stabilized austenitic chromium-nickel stainless steel. The addition of niobium stabilizes carbon in the form of niobium carbides and carbonitrides, effectively preventing chromium carbide precipitation at grain boundaries. This gives Type 347 outstanding resistance to intergranular corrosion after welding or after prolonged exposure to the sensitization temperature range (approximately 450–850°C). Compared with titanium-stabilized Type 321, niobium provides more stable high-temperature performance, making Type 347 the preferred choice for the most demanding continuous high-temperature service.
Type 347 retains the excellent toughness, good formability, and reliable fabricability of the 300-series austenitic stainless steels. It is widely used in high-temperature process equipment, exhaust systems, heat exchangers, pressure vessels, and expansion joints where both sensitization resistance and elevated-temperature stability are required.
SHH STEEL supplies ASME SA240 347 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 1 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 with a full range of surface finishes.
Material Specification
| Specification Element | Requirement | SHH STEEL Compliance |
|---|---|---|
| Primary Standard | ASME SA240 / SA240M | Full compliance |
| Steel Grade | Type 347 (UNS S34700) | Confirmed |
| Product Form | Plate, Sheet, Coil | Available |
| Delivery Condition | Solution Annealed | Standard |
| Thickness Range | 1 mm – 100 mm (thicker available) | Custom sizes supported |
| Width | Up to 2000–3000 mm | Available |
| Length | Up to 12000 mm or cut-to-length | Available |
| Surface Finish | No.1, 2B, BA, No.4, HL, Polished | Available |
| Certification | EN 10204 3.1 / ASME Mill Test Certificate | Available |
Chemical Composition
Heat Analysis (Ladle Analysis) according to ASME SA240 Type 347:
| Element | Content (%) |
|---|---|
| Carbon (C) | ≤ 0.08 |
| Silicon (Si) | ≤ 0.75 |
| Manganese (Mn) | ≤ 2.00 |
| Phosphorus (P) | ≤ 0.045 |
| Sulfur (S) | ≤ 0.030 |
| Chromium (Cr) | 17.00 – 19.00 |
| Nickel (Ni) | 9.00 – 13.00 |
| Niobium (Nb) | ≥ 10 × C% |
| Nitrogen (N) | ≤ 0.10 |
| Iron (Fe) | Balance |
Product Analysis (typical permissible variations):
| Element | Content (%) |
|---|---|
| Carbon (C) | ≤ 0.08 |
| Silicon (Si) | ≤ 0.75 |
| Manganese (Mn) | ≤ 2.00 |
| Phosphorus (P) | ≤ 0.045 |
| Sulfur (S) | ≤ 0.030 |
| Chromium (Cr) | 16.90 – 19.10 |
| Nickel (Ni) | 8.90 – 13.10 |
| Niobium (Nb) | ≥ 10 × C% |
| Nitrogen (N) | ≤ 0.10 |
The minimum niobium content of ten times the carbon percentage is the critical stabilizing requirement. Niobium combines preferentially with carbon, providing highly effective protection against intergranular corrosion and excellent long-term stability at elevated temperatures.
Mechanical Properties
Room-Temperature Mechanical Properties (Annealed Condition)
| Property | Value |
|---|---|
| Tensile Strength | ≥ 515 MPa (75 ksi) |
| Yield Strength (0.2%) | ≥ 205 MPa (30 ksi) |
| Elongation (in 50 mm) | ≥ 40% |
| Hardness | ≤ 217 HB / ≤ 95 HRB |
Elevated-Temperature Behavior ASME SA240 Type 347 maintains useful strength and excellent resistance to sensitization at temperatures up to approximately 900°C. It offers superior long-term high-temperature stability compared with titanium-stabilized Type 321.
Physical Properties
- Density: 7.93 g/cm³
- Melting Range: approximately 1400–1425°C
- Magnetic: Non-magnetic in the annealed condition
Material Comparison
| Grade | Stabilization | Primary Advantage | Typical Preference |
|---|---|---|---|
| SA240 Type 304L | Low carbon | Economical, excellent as-welded performance | Moderate temperature, heavy welding |
| SA240 Type 321 | Titanium | Good sensitization resistance + high-temp capability | Welded high-temperature service |
| SA240 Type 347 | Niobium | Superior high-temperature stability | Most severe continuous high-temperature service |
| SA240 Type 316Ti | Titanium + Mo | Stabilization + better pitting resistance | High-temperature + chloride service |
| SA240 Type 348 | Nb + Ta | Similar to 347 with tighter residual control | Nuclear and special high-temp applications |
Type 347 is frequently chosen when the highest level of high-temperature stability is required among the standard stabilized grades. It is generally preferred over astm a240 type 321 stainless steel sheet plate for long-term continuous service above 600–650°C. When chloride resistance is also needed, astm a240 type 316ti stainless steel sheet plate offers the additional benefit of molybdenum. For general welded service at lower temperatures, astm a240 type 304l stainless steel sheet plate remains the most economical option.
In the annealed condition, ASME SA240 Type 347 offers corrosion resistance similar to 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 exposure to the temperature range of 450–850°C.
It performs well in nitric acid and many organic media. Resistance to pitting and crevice corrosion in chloride environments is comparable to 304 and inferior to molybdenum-containing grades such as 316L or 316Ti. For combined high-temperature and chloride service, Type 316Ti is often preferred.
Weldability
ASME SA240 Type 347 has excellent weldability by all standard fusion and resistance welding processes. Because the grade is niobium-stabilized, it can normally be used in the as-welded condition without risk of intergranular corrosion.
Matching niobium-stabilized filler metals (E347 / ER347) are recommended to maintain stabilization in the weld metal. Standard 308L fillers may be used when service temperatures are moderate. Post-weld heat treatment is generally not required for corrosion resistance.
Heat Treatment
ASME SA240 Type 347 is supplied in the solution-annealed condition.
Recommended Solution Annealing Parameters
- Temperature range: 980 – 1150°C (typically 1040 – 1120°C)
- Holding (soaking) time: – Plates ≤ 25 mm: minimum 10–20 minutes after the section reaches temperature – Plates 25–50 mm: minimum 20–40 minutes – Plates > 50 mm: 30–60 minutes or longer to ensure uniformity throughout the cross-section
- Cooling: Rapid cooling (water quench preferred for thicker plates) to retain the stabilized structure and maximum corrosion resistance
An optional stabilizing heat treatment at approximately 840–900°C for several hours can be applied in special cases to ensure complete niobium carbide precipitation, although modern melting practices usually make this unnecessary for most applications.
Surface Finishes
| Finish | Description | Typical Use / Keywords |
|---|---|---|
| No.1 | Hot-rolled, annealed and pickled | SA240 347 No.1 – most common for pressure vessel and industrial plate |
| 2B | Cold-rolled, annealed, pickled, skin-passed | SA240 347 2B – general fabrication and process equipment |
| BA | Bright Annealed | SA240 347 BA – clean and special applications |
| No.4 | Brushed (satin) finish | SA240 347 No.4 – architectural or visible surfaces |
| HL | Hairline finish | SA240 347 HL – decorative panels |
| Polished | Mirror or custom polish | SA240 347 Polished – sanitary and high-end applications |
SHH STEEL regularly supplies ASME SA240 347 in No.1 and 2B finishes, and can provide BA, No.4, HL, and polished finishes according to project requirements.
Tolerances
Dimensional tolerances conform to ASME SA240 and the general requirements of ASTM A480. Thickness, width, length, and flatness are controlled within standard or tighter agreed limits.
Equivalent Material Grades
| Grade / Designation | Standard | Notes |
|---|---|---|
| SA240 Type 347 | ASME SA240 | — |
| A240 Type 347 | ASTM A240 | Essentially identical |
| UNS S34700 | — | Unified Numbering System |
| 1.4550 / X6CrNiNb18-10 | EN 10088-2 | European equivalent |
| SUS347 | JIS G4305 | Japanese equivalent |
| 06Cr18Ni11Nb | GB/T 3280 | Chinese equivalent |
Related grades frequently evaluated with ASME SA240 347 include astm a240 type 321 stainless steel sheet plate, astm a240 type 316ti stainless steel sheet plate, astm a240 type 304l stainless steel sheet plate, and astm a240 type 348 stainless steel sheet plate.
Applications
ASME SA240 Type 347 is widely used in high-temperature and welded process equipment:
| Industry / Sector | Typical Components / Equipment |
|---|---|
| Aerospace & Automotive | Exhaust systems, manifolds, expansion joints |
| Chemical & Petrochemical | High-temperature reactors, piping, heat exchangers |
| Power Generation | Boiler components, superheater parts |
| Heat Treatment Equipment | Fixtures, radiant tubes, furnace parts |
| Pressure Vessels | High-temperature shells and components |
| Refinery | Hot-process piping and vessels |
| Industrial Furnaces | Structural parts operating at elevated temperature |
| General Fabrication | Welded structures requiring long-term high-temp stability |
Why Choose SHH STEEL
SHH STEEL is a China Mill-Direct Supply and Mill Direct Exporter of stainless steel plate. We maintain long-term strategic cooperation with major Chinese stainless steel mills and supply ASME SA240 Type 347 with the following advantages:
- Competitive mill-direct pricing
- Consistent quality and complete heat traceability
- Full Mill Test Certificates (EN 10204 3.1 / ASME)
- Flexible dimensions and surface finishes (including SA240 347 No.1 and SA240 347 2B)
- Technical support for high-temperature material selection
- Reliable worldwide logistics and export documentation
FAQ
- What is the main advantage of SA240 347 over SA240 321?Both are stabilized grades, but Type 347 uses niobium stabilization, which generally provides better long-term high-temperature stability and performance than the titanium-stabilized Type 321.
- When should I choose Type 347 instead of Type 316Ti?Choose Type 347 when maximum high-temperature stability is the primary requirement and chloride levels are moderate. Choose Type 316Ti when improved pitting resistance is also needed.
- Is ASME SA240 347 magnetic?Non-magnetic in the annealed condition. It may become slightly magnetic after heavy cold working.
- Can SHH STEEL supply dual-certified ASME SA240 / ASTM A240 Type 347?Yes, dual certification is commonly available.
- What is the density of SA240 Type 347?7.93 g/cm³.
Conclusion
ASME SA240 347 Stainless Steel Plate (SA240 Type 347) is a niobium-stabilized austenitic stainless steel that offers excellent resistance to intergranular corrosion and superior high-temperature stability. It is the preferred stabilized grade for many continuous high-temperature welded applications where long-term reliability is critical.
As a professional China Mill-Direct Supply and Mill Direct Exporter, SHH STEEL provides high-quality ASME SA240 Type 347 plate with competitive pricing, full certification, and complete technical support.
Contact SHH STEEL today for stock availability, surface finish options (including SA240 347 No.1 and SA240 347 2B), or a competitive quotation.
ASME SA240 347 Stainless Steel Plate, SA240 Type 347, SA240 347, ASME SA240 Type 347, 347 stainless steel plate, SA240 347 supplier
Quality Steel Needed? Inquire for Offers
Related Products
