ASTM A240 Type 348 Stainless Steel Sheet & Plate
What is ASTM A240 Type 348 Stainless Steel Sheet and Plate?
As a professional stainless steel supplier, SHH STEEL is pleased to present ASTM A240 Type 348 Stainless Steel Sheet and Plate. Also known as UNS S34800, this niobium- and tantalum-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).
Type 348 is closely related to Type 347 but features a controlled low maximum tantalum content. The combined niobium + tantalum addition (minimum 10× carbon content) stabilizes carbon and prevents chromium carbide precipitation at grain boundaries. SHH STEEL supplies ASTM A240 Type 348 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, nuclear-related and high-temperature industrial projects worldwide.
Material Specification
ASTM A240 Type 348 stainless steel sheet and plate are manufactured in accordance with ASTM A240/A240M and ASME SA-240. This specification covers chromium-nickel-niobium-tantalum 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 348 | 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 348 is carefully controlled, with niobium and limited tantalum 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 |
| Tantalum (Ta) | ≤ 0.10 | 0.10 max | Controlled low tantalum content |
| Nitrogen (N) | ≤ 0.10 | 0.10 max | Strength contribution |
Mechanical Properties
In the solution-annealed condition, ASTM A240 Type 348 provides reliable strength and excellent ductility, comparable to Type 347.
| 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 348 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 348 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 348 offers excellent weldability using all common fusion welding processes, including GTAW (TIG), GMAW (MIG), SMAW and plasma welding. The niobium-tantalum 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 or ER348 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 348 | ASTM A240 / ASME SA-240 | — |
| UNS S34800 | Unified Numbering System | S34800 |
| Similar to 1.4550 | EN (with Ta control) | X6CrNiNb18-10 related |
| Related Chinese grades | GB/T series | Nb-stabilized 18Cr-11Ni types with low Ta |
| SUS348 | JIS (reference) | — |
Applications
ASTM A240 Type 348 is used in applications requiring resistance to intergranular corrosion after exposure to sensitization temperatures, particularly where controlled low tantalum content is specified. Typical applications are shown below with relevant keywords:
| Application Area | Typical Components / Uses (Keywords) |
|---|---|
| Chemical Processing | Reactors, heat exchangers, process equipment – A240 348 Chemical Processing |
| Petrochemical Industry | Furnace components, high-temp piping – A240 348 Petrochemical |
| Power Generation | High-temperature components, heat recovery systems – A240 348 Power |
| Nuclear & Specialized Service | Applications requiring low tantalum content – A240 348 Nuclear |
| Heat Exchangers & Pressure Vessels | Continuous service in sensitization range – A240 348 Heat Exchanger |
| General High-Temperature Service | Welded structures exposed to elevated temperatures – A240 348 High Temperature |
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 348 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 specialized high-temperature applications worldwide.
FAQ
- What is the main difference between Type 347 and Type 348?Both are niobium-stabilized grades. Type 348 has a controlled maximum tantalum content (typically ≤ 0.10%), while Type 347 allows higher combined Nb+Ta without the same strict Ta limitation. Type 348 is often specified when low tantalum is required.
- What is the difference between 348 and 348H?Type 348H is the high-carbon version (C 0.04–0.10%) with mandatory grain size requirements for improved creep strength in continuous high-temperature service. Type 348 has carbon ≤ 0.08%.
- What are the equivalent grades of ASTM A240 Type 348?The primary designation is UNS S34800. It is closely related to EN 1.4550 (with tantalum control) and similar niobium-stabilized grades in Chinese and Japanese standards.
- What is the density of ASTM A240 Type 348?Approximately 8.00 g/cm³.
- Approximately 8.00 g/cm³.Yes. Due to niobium-tantalum stabilization, it performs well in continuous service within the sensitization temperature range and offers good high-temperature strength.
Conclusion
ASTM A240 Type 348 Stainless Steel Sheet and Plate from SHH STEEL provide excellent resistance to intergranular corrosion through niobium-tantalum stabilization with controlled low tantalum content. 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 specialized elevated-temperature applications worldwide.
Contact SHH STEEL today for your ASTM A240 Type 348 requirements.
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