ASTM B443 UNS N06625 Alloy 625 Plate, Sheet & Strip | ASME SB-443
We supply ASTM B443 UNS N06625 Alloy 625 plate, sheet and strip for offshore, marine, chemical processing, pollution-control and high-temperature industrial applications.
Alloy 625 / UNS N06625 / W.Nr. 2.4856 is a nickel-chromium-molybdenum-niobium alloy combining high mechanical strength with excellent resistance to pitting, crevice corrosion and chloride-ion stress-corrosion cracking.
ASTM B443 and ASME SB-443 material is available in Grade 1 annealed and Grade 2 solution-annealed conditions, with customized dimensions and EN 10204 3.1 material certification.
ASTM B443 Alloy 625 Plate & Sheet
ASTM-B443 covers rolled Alloy 625 plate, sheet and strip manufactured from UNS N06625.
| Product | Typical Supply |
|---|---|
| Material | Alloy 625 |
| UNS | N06625 |
| W.Nr. | 2.4856 |
| Standard | ASTM B443 / ASME SB-443 |
| Product Form | Plate / Sheet / Strip / Coil |
| Grade | Grade 1 / Grade 2 |
| Heat Treatment | Annealed / Solution Annealed |
| Thickness | 0.1–12 mm typical supply |
| Width & Length | Standard / Customized |
| Certification | EN 10204 3.1 MTC available |
Typical available sheet and plate dimensions include:
- 1000 × 2000 mm
- 1220 × 2440 mm
- 1500 × 3000 mm
- 2000 × 2000 mm
- 2000 × 4000 mm
Other thicknesses and cut-to-size plates can be evaluated according to project requirements.
What Is UNS N06625 Alloy 625?
Alloy 625 is a nickel-chromium-molybdenum alloy strengthened by the addition of niobium.
Its high nickel content provides good resistance to chloride-ion stress-corrosion cracking, while the combination of molybdenum and niobium contributes to high strength without requiring precipitation-hardening heat treatment.
Molybdenum also provides excellent resistance to pitting and crevice corrosion.
Key characteristics include:
- Excellent resistance to pitting and crevice corrosion
- High resistance to chloride-ion stress-corrosion cracking
- Excellent seawater corrosion resistance
- High mechanical strength
- Good resistance to oxidizing and non-oxidizing environments
- Good weldability
- Good fatigue strength
- Useful mechanical properties from cryogenic to elevated temperatures
ASTM B443 Grade 1 vs Grade 2
ASTM B443 specifies two heat-treatment conditions for UNS N06625.
| Item | Grade 1 | Grade 2 |
|---|---|---|
| Condition | Annealed | Solution Annealed |
| Typical Service Temperature | Up to 593°C / 1100°F | Above 593°C / 1100°F |
| Main Performance Focus | Strength + corrosion resistance | Creep & rupture resistance |
| Typical Application | Marine / chemical / general service | Elevated-temperature equipment |
Grade 2 is not simply a higher-quality version of Grade 1. The correct condition depends on the design temperature, mechanical requirements and applicable equipment code.
For high-temperature pressure equipment, the required grade should be clearly stated in the purchase specification.
Alloy 625 Chemical Composition
Typical composition limits for UNS N06625 are:
| Element | Composition, wt.% |
|---|---|
| Nickel (Ni) | 58.0 min |
| Chromium (Cr) | 20.0–23.0 |
| Molybdenum (Mo) | 8.0–10.0 |
| Niobium + Tantalum (Nb+Ta) | 3.15–4.15 |
| Iron (Fe) | 5.0 max |
| Carbon (C) | 0.10 max |
| Manganese (Mn) | 0.50 max |
| Silicon (Si) | 0.50 max |
| Phosphorus (P) | 0.015 max |
| Sulfur (S) | 0.015 max |
| Aluminum (Al) | 0.40 max |
| Titanium (Ti) | 0.40 max |
The combination of approximately 8–10% Mo and 3.15–4.15% Nb+Ta is an important reason for Alloy 625’s high strength and localized-corrosion resistance.
ASTM B443 Mechanical Properties
Mechanical requirements depend on the product form and heat-treatment grade.
| Product / Condition | Tensile Strength Min. | Yield Strength Min. | Elongation Min. |
|---|---|---|---|
| Grade 1 Cold-Rolled Sheet & Strip | 827 MPa | 414 MPa | 30% |
| Grade 1 Hot-Rolled Plate / Sheet | 758 MPa | 379 MPa | 30% |
| Grade 2 Solution-Annealed Products | 690 MPa | 276 MPa | 30% |
The applicable mechanical requirements should be confirmed according to the specified ASTM B443 edition, product form, thickness and heat-treatment condition.
Corrosion Resistance of Alloy 625
One of the major advantages of Alloy 625 plate is its ability to withstand a wide range of severe corrosive environments.
The high nickel content provides strong resistance to chloride-ion stress-corrosion cracking, while molybdenum improves resistance to pitting and crevice corrosion.
Alloy 625 can be considered for:
- Seawater and marine environments
- Brine and chloride-containing fluids
- Chemical process solutions
- Acid-containing process environments
- Flue-gas scrubber systems
- Offshore production equipment
- Pollution-control equipment
Final suitability must still be evaluated according to temperature, concentration, flow velocity, contaminants and equipment design.
Applications of ASTM B443 Alloy 625 Plate
ASTM B443 N06625 plate and sheet are widely used in:
- Offshore oil and gas equipment
- Marine engineering
- Seawater systems
- Chemical processing plants
- Heat exchangers
- Flue-gas desulfurization systems
- Scrubbers and stack liners
- Pollution-control equipment
- Pressure vessels
- Reactor components
- Aerospace equipment
- High-temperature industrial equipment
- Cryogenic equipment
ASTM B443 vs ASME SB-443
ASTM B443 is the ASTM material specification for UNS N06625 Alloy 625 plate, sheet and strip.
ASME SB-443 is the corresponding ASME material specification commonly specified for material used in ASME Boiler and Pressure Vessel Code applications.
For pressure equipment, the required ASME Code edition, grade, heat-treatment condition and certification requirements should be stated in the purchase order.
Plate vs Sheet vs Strip
ASTM B443 covers several flat-rolled product forms:
- Plate – Thicker flat-rolled material for pressure equipment and fabricated components.
- Sheet – Thinner wide flat-rolled material.
- Strip – Narrower flat-rolled material, frequently supplied in coils.
The actual classification depends on product dimensions and the applicable ASTM B443 definitions.
Inspection & Certification
Alloy 625 plate and sheet can be supplied with:
- EN 10204 3.1 Material Test Certificate
- Chemical composition analysis
- Tensile testing
- Dimensional inspection
- Surface inspection
- PMI testing
- Ultrasonic testing when specified
- Corrosion testing when required
- Third-party inspection
- Full heat-number traceability
Frequently Asked Questions
What is ASTM B443 UNS N06625?
ASTM B443 UNS N06625 refers to Alloy 625 nickel-chromium-molybdenum-niobium plate, sheet and strip manufactured according to ASTM B443 requirements.
What is the difference between ASTM B443 Grade 1 and Grade 2?
Grade 1 is annealed and normally used at service temperatures up to 593°C / 1100°F. Grade 2 is solution annealed and is normally selected above 593°C when creep and rupture resistance are important.
Is Alloy 625 suitable for seawater?
Yes. Alloy 625 has excellent resistance to seawater, pitting, crevice corrosion and chloride-ion stress-corrosion cracking, making it widely used in marine and offshore equipment. Actual material suitability should still be confirmed against operating conditions.
Is Inconel 625 the same as UNS N06625?
UNS N06625 is the standardized alloy designation. INCONEL® alloy 625 is a registered trade name associated with Special Metals Corporation. In commercial markets, Alloy 625 and Inconel 625 are commonly used to refer to UNS N06625 material.
Related Nickel Alloy Products
- ASTM B168 Alloy 600 Plate – UNS N06600 Ni-Cr-Fe alloy for corrosive and high-temperature applications.
- ASTM B168 Alloy 601 Plate – Ni-Cr-Al alloy with enhanced high-temperature oxidation resistance.
- ASTM B424 Alloy 825 Plate – Ni-Fe-Cr-Mo-Cu alloy for sulfuric and phosphoric acid environments.
- ASTM B575 Alloy C276 Plate – Ni-Mo-Cr alloy for severe chemical corrosion service.
- ASTM B444 Alloy 625 Seamless Pipe & Tube – UNS N06625 seamless pipe and tube.
- ASTM B446 Alloy 625 Round Bar – Alloy 625 bar and rod.
- ASTM B366 Alloy 625 Pipe Fittings – N06625 elbows, tees, reducers and fittings.
- ASTM B564 Alloy 625 Flanges – Forged N06625 flanges for corrosive piping systems.
ASTM B443 Alloy 625 Plate Supplier
We supply ASTM B443 / ASME SB-443 UNS N06625 Alloy 625 plate, sheet, strip and coil for international marine, offshore, chemical and high-temperature projects.
Customized dimensions, cut-to-size material, Grade 1 or Grade 2 heat treatment, special testing and complete inspection documentation can be supplied according to customer specifications.
For quotation, please provide the grade, product form, thickness, width, length, quantity and required inspection documents.
