ASTM A240 Type 347 Stainless Steel Sheet & Plate
What is ASTM A240 Type 347 Stainless Steel Sheet and Plate?
As a professional stainless steel supplier, SHH STEEL is pleased to present ASTM A240 Type 347 Stainless Steel Sheet and Plate. Also known as SS347 or UNS S34700, this niobium (columbium)-stabilized austenitic grade is designed to provide excellent resistance to intergranular corrosion after welding or continuous service in the sensitization temperature range (approximately 450–850°C).
The addition of niobium (minimum 10× carbon content, up to 1.00%) stabilizes carbon in the form of niobium carbides, preventing chromium carbide precipitation at grain boundaries. Type 347 offers good corrosion resistance, high-temperature strength and excellent weldability. SHH STEEL supplies ASTM A240 Type 347 in both sheet and plate forms, covering thicknesses from 0.5 mm to 100 mm, with widths up to 2500 mm and lengths up to 12000 mm. Custom sizes and surface finishes are available.
The material is typically delivered in the solution-annealed condition with full Mill Test Certificates (EN 10204 3.1). Whether for thin sheet fabrication or heavy plate applications, SHH STEEL provides consistent quality for chemical, petrochemical and high-temperature industrial projects worldwide.
Material Specification
ASTM A240 Type 347 stainless steel sheet and plate are manufactured in accordance with ASTM A240/A240M and ASME SA-240. This specification covers chromium-nickel-niobium stainless steel plate, sheet and strip for pressure vessels and general applications.
| Specification Element | Requirement | SHH STEEL Compliance |
|---|---|---|
| Primary Standard | ASTM A240 / ASME SA-240 Type 347 | Full compliance |
| Product Form | Sheet and Plate | Both available |
| Thickness Range | 0.5 mm – 100 mm | Custom sizes available |
| Width / Length | Up to 2500 mm / 12000 mm | Custom fabrication supported |
| Surface Finish | 2B, No.1, BA, HL | Multiple options |
| Heat Treatment Condition | Solution Annealed | Standard supply condition |
| Certification | EN 10204 3.1 / 3.2 | Available |
Chemical Composition
The chemical composition of ASTM A240 Type 347 is carefully controlled, with niobium added for stabilization against intergranular corrosion.
| Element | Content (%) | Standard Limit | Role |
|---|---|---|---|
| Carbon (C) | ≤ 0.08 | 0.08 max | Strength and corrosion balance |
| Manganese (Mn) | ≤ 2.00 | 2.00 max | Deoxidation and strength |
| Phosphorus (P) | ≤ 0.045 | 0.045 max | Impurity control |
| Sulfur (S) | ≤ 0.030 | 0.030 max | Cleanliness |
| Silicon (Si) | ≤ 0.75 | 0.75 max | Deoxidation |
| Chromium (Cr) | 17.00 – 19.00 | 17.00 – 19.00 | Corrosion and oxidation resistance |
| Nickel (Ni) | 9.00 – 13.00 | 9.00 – 13.00 | Austenite stability and toughness |
| Niobium (Nb) + Tantalum (Ta) | 10×C min – 1.00 max | 10×C min – 1.00 max | Stabilization against intergranular corrosion |
| Nitrogen (N) | ≤ 0.10 | 0.10 max | Strength contribution |
Mechanical Properties
In the solution-annealed condition, ASTM A240 Type 347 provides reliable strength and excellent ductility.
| Property | Value | Test Method |
|---|---|---|
| Tensile Strength | ≥ 515 MPa (75 ksi) | ASTM A370 |
| Yield Strength (0.2% Offset) | ≥ 205 MPa (30 ksi) | ASTM A370 |
| Elongation in 50 mm | ≥ 40% | ASTM A370 |
| Hardness | ≤ 201–217 HB / ≤ 95 HRB | ASTM E10/E18 |
| Density | 8.00 g/cm³ | — |
Delivery Conditions
SHH STEEL supplies ASTM A240 Type 347 primarily in the solution-annealed and pickled condition. Detailed capabilities by surface finish are as follows:
2B Finish (Cold-rolled, annealed, pickled and skin-passed)
- Typical thickness range: 0.5 mm – 6.0 mm (most common 0.8 mm – 3.0 mm)
- Maximum width: up to 1500–2000 mm depending on thickness
- Preferred for applications requiring a smooth surface and good flatness.
No.1 Finish (Hot-rolled, annealed and pickled)
- Typical thickness range: 3.0 mm – 100 mm (most common 4.0 mm – 50 mm)
- Maximum width: up to 2000–2500 mm
- Standard finish for heavy plates used in chemical equipment, heat exchangers and high-temperature components.
Other Finishes
- BA (Bright Annealed): Available in thinner gauges
- HL (Hairline): Available on request
Protective PVC film can be applied on one or both sides. Precision cutting (plasma, laser or waterjet) and closer dimensional tolerances are available upon request.
Tolerances
Dimensional tolerances for ASTM A240 Type 347 sheet and plate follow ASTM A480/A480M.
- Thickness tolerances vary by product form and thickness. Cold-rolled sheet has tighter controls, while hot-rolled plate follows standard allowable deviations.
- Width tolerance is typically +6 mm / 0 mm.
- Length tolerance for cut-to-length material is normally +10 mm / 0 mm.
- Flatness is controlled according to ASTM A480; improved flatness can be supplied for precision fabrication.
- Edge conditions include mill edge, slit edge, sheared edge or plasma/laser cut edge according to customer preference.
Tighter tolerances can be arranged for special projects.
Weldability
ASTM A240 Type 347 offers excellent weldability using all common fusion welding processes, including GTAW (TIG), GMAW (MIG), SMAW and plasma welding. The niobium stabilization provides outstanding resistance to intergranular corrosion in the heat-affected zone, even without post-weld annealing in many applications.
Matching filler metals such as ER347 are commonly recommended. Preheating is generally not required. Proper cleaning and passivation after welding are recommended to restore full corrosion resistance, especially in chemical environments.
Equivalent Material Grades
| Grade | Standard | Designation |
|---|---|---|
| Type 347 | ASTM A240 / ASME SA-240 | — |
| UNS S34700 | Unified Numbering System | S34700 |
| 1.4550 | EN 10088 / EN 10028-7 | X6CrNiNb18-10 |
| SUS347 | JIS G4304 / G4305 | — |
| 06Cr18Ni11Nb | GB/T 20878 / GB/T 4237 | Chinese National Standard |
| X6CrNiNb18-10 | DIN / EN | — |
Applications
ASTM A240 Type 347 is widely used in applications requiring resistance to intergranular corrosion after exposure to sensitization temperatures and good high-temperature performance. Typical applications are shown below with relevant keywords:
| Application Area | Typical Components / Uses (Keywords) |
|---|---|
| Chemical Processing | Reactors, heat exchangers, process equipment – A240 347 Chemical Processing |
| Petrochemical Industry | Furnace components, high-temp piping, reformer parts – A240 347 Petrochemical |
| Power Generation | Boiler components, superheater supports, heat recovery systems – A240 347 Power |
| Heat Exchangers & Pressure Vessels | Continuous service equipment in sensitization range – A240 347 Heat Exchanger |
| Aerospace & High-Temperature Service | Exhaust systems, high-temp structural parts – A240 347 High Temperature |
| General Industrial | Welded structures exposed to elevated temperatures – A240 347 Industrial |
Why Choose SHH STEEL
SHH STEEL maintains long-term strategic cooperation with major Chinese stainless steel mills and acts as a first-level (primary) agent for these mills. This direct partnership enables us to offer competitive pricing advantages, faster delivery times and consistent quality assurance that many intermediate traders cannot match.
All ASTM A240 Type 347 material is sourced from reputable Chinese mills under strict quality control, supplied with complete Mill Test Certificates, and supported by our professional export team. Customers benefit from reliable supply, short lead times, technical support and cost-effective solutions for chemical, petrochemical and high-temperature applications worldwide.
FAQ
- What is the main advantage of 347 compared with 304 or 304L?Type 347 is niobium-stabilized, providing excellent resistance to intergranular corrosion after continuous exposure to the sensitization temperature range (450–850°C). It also offers better high-temperature strength than standard 304/304L.
- What is the difference between 347 and 347H?Type 347H has a higher controlled carbon content (0.04–0.10%) and mandatory grain size requirements for improved creep strength in continuous high-temperature service. Type 347 has carbon ≤ 0.08% and is primarily selected for intergranular corrosion resistance.
- What are the equivalent grades of ASTM A240 Type 347?Common equivalents include UNS S34700, EN 1.4550 (X6CrNiNb18-10), JIS SUS347 and Chinese 06Cr18Ni11Nb.
- What is the density of ASTM A240 Type 347?Approximately 8.00 g/cm³.
- Is Type 347 suitable for continuous high-temperature service?Yes. Due to niobium stabilization, it performs well in continuous service within the sensitization temperature range and offers good high-temperature strength.
Conclusion
ASTM A240 Type 347 Stainless Steel Sheet and Plate from SHH STEEL provide excellent resistance to intergranular corrosion through niobium stabilization, combined with good high-temperature strength and weldability. With strict quality control, flexible sizing options, competitive pricing through direct mill partnerships and professional global export service, we deliver trusted solutions for chemical processing, petrochemical and elevated-temperature applications worldwide.
Contact SHH STEEL today for your ASTM A240 Type 347 requirements.
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