Alloy 20 plates or alloy 20 was designed in particular to face up to sulfuric acid. Its nickel, chromium, molybdenum and copper tiers all offer remarkable trendy corrosion resistance. Confined carbon plus columbium stabilization allows welded fabrications for use in corrosive environments, typically without put up-weld heat treatment. At 33% nickel, alloy 20 has practical immunity to chloride strain corrosion cracking. This alloy is often selected to solve SCC issues, which might also arise with 316L stainless.
Terms used above: “Columbium” is the older name for niobium (Nb), which ties up carbon so welds resist intergranular attack. “Chloride strain corrosion cracking” and “SCC” mean chloride stress corrosion cracking. Alloy 20 has much better resistance to it than 316L, but “practical immunity” is not a guarantee: very hot, concentrated chloride conditions can still crack nickel-iron alloys, so check the actual service conditions.
Alloy 20 Plates: Purchasing Specification
| Requirement | What to specify |
|---|---|
| Grade and form | Alloy 20 / UNS N08020 plate (W.Nr. 2.4660). |
| Product standard | ASTM B463 or ASME SB463; state the required edition and any supplementary requirements. |
| Dimensions | Thickness × width × length and number of plates. This page does not publish a size range, so send the sizes you need. |
| Condition and finish | Annealed (normally stabilized-annealed); hot-rolled or cold-rolled; surface finish, thickness tolerance and flatness. |
| Processing | Full plate, cut piece or profile; drawing, quantity, edge finish and machining allowance. |
| Documents and inspection | Inspection certificate type, heat traceability, PMI, corrosion tests and third-party inspection where required. |
Dimensions, Condition and Tolerances
Specify thickness × width × length and the number of plates or pieces. For profiles or blanks, provide a dimensioned drawing with units, revision and finished-part tolerances, and say whether the sizes are finished dimensions or include a machining allowance.
ASTM B463 covers hot-rolled and cold-rolled plate, sheet and strip, and sets the permitted variations in thickness, width, length and flatness. Attach your own limits where they are tighter, and state the surface finish and edge condition you need.
Chemistry
| Ni | Cr | Mo | Mn | Cu | Si | C | S | P | Cb+Ta | Fe | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| MIN | 32.5 | 19.0 | 2.0 | - | 3.0 | - | - | - | - | 8.0 x C 1.0 | - |
| MAX | 35.0 | 21.0 | 3.0 | 2.0 | 4.0 | 1.0 | 0.06 | 0.035 | 0.035 | - | Balance |
Reading the chemistry table: “8.0 x C 1.0” in the MIN row means niobium plus tantalum (Cb+Ta) of at least 8 × the carbon content and no more than 1.0%; the 1.0 is a maximum. The limits shown are tighter than ASTM B463 in places: B463 allows 32.0–38.0% nickel, 0.07% maximum carbon and 0.045% maximum phosphorus for N08020. Order acceptance follows the specification and edition on your purchase order, checked against the heat certificate.
Specifications
- ASME SA 240, ASME SB 366, ASME SB 463
- ASTM A 240, ASTM B 366
- ASTM B 463
- ASTM B 473
- EN 2.4660
- UNS N08020
- Werkstoff 2.4660
Which Specification Applies to Plate?
The list above mixes plate, fitting and bar standards with material identifiers. For Alloy 20 plate, name ASTM B463 or ASME SB463 and UNS N08020 on the order.
| Reference | What it covers | Use for this plate order |
|---|---|---|
| ASTM B463 / ASME SB463 | N08020 plate, sheet and strip | The product specification to state |
| ASTM B366 / ASME SB366 | Factory-made wrought nickel-alloy welding fittings | Not a plate specification |
| ASTM B473 | N08020 bar and wire | Not a plate specification |
| ASTM A240 / ASME SA240 | Stainless and heat-resisting steel plate, sheet and strip | Use only if your purchase specification calls for it and the edition lists the grade |
| UNS N08020, W.Nr. 2.4660 | Material identifiers | Identify the grade; they do not set plate requirements |
“EN 2.4660”: 2.4660 is a German/European material number (Werkstoff-Nr.), the same identifier as “Werkstoff 2.4660” in the list. It is not an EN standard. The European material name is NiCr20CuMo.
Inventory
Alloy 20 Coil, Alloy 20 Plate, Alloy 20 Sheet, Alloy 20 Weld Wire Supplier and exporters.
This page covers Alloy 20 plate. Ask for coil, sheet or weld wire separately in your enquiry, with the form, size and specification for each item.
Common Trade Names
Carpenter® 20, 20CB-3®
Brand distinction: Carpenter® 20 and 20Cb-3® are registered trade names of Carpenter Technology Corporation for its N08020 alloy. Generic Alloy 20 / UNS N08020 plate is not automatically one of these brands. If a project requires a specific brand or producer, state it in the enquiry and ask for the mill certificate that shows it.
Features
- Excellent resistance to hot sulfuric acid
- Resistant to intergranular corrosion in the as-welded condition
- Chloride stress corrosion cracking resistance
Why Select Alloy 20 Plates?
Alloy 20 is chosen where standard austenitic stainless steels corrode too fast in sulfuric acid or crack in hot chloride-bearing media. Copper and molybdenum improve resistance in reducing acids, high nickel improves resistance to chloride stress corrosion cracking, and niobium stabilization limits sensitization at welds. Its performance depends on acid concentration, temperature, aeration and contaminants such as chlorides or oxidizing ions, so selection should be based on the actual process conditions.
| Consideration | 316L stainless | Alloy 20 (N08020) | Alloy 825 (N08825) |
|---|---|---|---|
| Nickel, nominal | 10–14% | 32–38% | 38–46% |
| Copper addition | None specified | 3.0–4.0% | 1.5–3.0% |
| Chloride SCC resistance | Susceptible in hot chloride service | High | High |
| Typical reason to choose | General corrosion at lower cost | Sulfuric acid service; replacing 316L that cracks | Wider range of reducing and oxidizing acids |
These grades are not interchangeable. Compare corrosion data for your process and see the Alloy 825 Plates page if you are evaluating both nickel alloys.
Applications
- Sulfuric acid pickling tanks, racks and heating coils
- Phosphate coating drums and racks
- Heat exchangers
- Bubble caps
- Process piping
- Mixing tanks
- Chemical and petroleum process equipment
Specify the Conditions Behind the Application
The applications above are common uses of the material. Match the plate to your equipment’s actual media and design requirements.
| Component or duty | Information for selection |
|---|---|
| Pickling tanks, racks and heating coils | Acid type and concentration, temperature, aeration, dissolved metals and chloride content. |
| Heat exchangers | Media on both sides, wall temperature, chlorides, pressure and design code. |
| Mixing tanks and process equipment | Process chemistry, temperature range, agitation or velocity, and cleaning cycles. |
| Welded fabrications | Joint design, filler metal, whether post-weld cleaning or heat treatment is required. |
Physical Properties
Density: 0.278 lb/in3 annealed
Melting Point: 2525-2630°F
Electrical Resistivity: 651 Ohm-circ mil/ft
| Temperature, °F | 70 | 212 | 392 | 572 | 752 | 842 | 932 |
|---|---|---|---|---|---|---|---|
| Coefficient* of Thermal Expansion, in/in°F x 10-6 | - | 8.16 | 8.37 | 8.62 | 8.62 | 8.84 | 8.91 |
| Thermal Conductivity Btu • ft/ft2 • hr • °F |
6.7 | 7.57 | 8.56 | 9.53 | 10.5 | - | - |
| Modulus of Elasticity, Dynamic psi x 106 | 28 | - | - | - | - | - | - |
* 70°F to indicated temperature
Density: Published producer data for N08020 give about 0.292 lb/in³ (8.08 g/cm³), higher than the 0.278 lb/in³ shown above. Use the producer’s or certificate value for weight calculations.
Units and metric equivalents: “x 10-6” and “x 106” mean ×10⁻⁶ and ×10⁶. 2525–2630°F is about 1385–1443°C; 651 ohm·circ mil/ft is about 1.08 µΩ·m; thermal conductivity in Btu·ft/(ft²·h·°F) multiplied by 1.731 gives W/(m·K), so 6.7 is about 11.6 W/(m·K); 8.16 ×10⁻⁶ /°F is about 14.7 ×10⁻⁶ /K; 28 ×10⁶ psi is about 193 GPa. These are reference values, not batch test results.
Mechanical Properties
Minimum Specified Properties, Asme Sb-688 Plate
| Ultimate tensile strength, ksi | 80 |
| 0.2% yield strength, ksi | 35 |
| Elongation, % | 30 |
| Hardness MAX, Brinell | 217 |
Specification reference: ASME SB-688 covers other alloys (UNS N08366 and N08367), not Alloy 20. For N08020 plate, the minimum properties are set by ASTM B463 / ASME SB463. Check the values above against the edition named on your purchase order.
Typical Tensile Properties, Bar
| Temperature, °F | 70 |
| Ultimate Tensile Strength, ksi | 91 |
| 0.2% Yield Strength, ksi | 48 |
| Elongation, % | 45 |
| Charpy Impact V-notch, ft-lbs | 200 |
Bar, not plate: These are typical room-temperature values for bar. Plate acceptance depends on the specified minimums and the results on the heat certificate, not on typical bar data.
Cutting, Fabrication and Welding
Champak Industries describes full and part plate/profile supply and a plasma-cutting service. Send drawings, piece quantities, tolerances, edge finish and machining allowances for your Alloy 20 requirement.
Forming and machining
Alloy 20 forms and machines much like austenitic stainless steel but work-hardens, so use rigid set-ups, sharp tools and positive feeds. Remove the heat-affected edge from thermal cutting where the drawing requires it. It is not hardened by heat treatment.
Welding
Weld with a qualified procedure and a matching filler, commonly AWS ER320LR, with low heat input and clean joints. Post-weld heat treatment is usually not needed; clean or pickle weld areas where corrosion service demands it.
Testing, Certificates and Heat Traceability
Specify the inspection-document type and heat identification when ordering. Request chemistry, mechanical results, dimensions and delivery condition to the governing specification. For cut pieces, state how identification must be carried from the parent plate to each piece.
| Requirement | What to identify in the order |
|---|---|
| Inspection document | Certificate type (for example EN 10204 3.1 or 3.2) showing heat number, chemistry, mechanical results and condition |
| Heat traceability | Heat marking on each plate and how it is transferred to cut pieces |
| Corrosion testing | Intergranular corrosion test, if required: test method, sample condition and acceptance criteria |
| PMI and inspection | Positive material identification, dimensional checks and any buyer or third-party witness |
A management-system certificate is separate from a material inspection certificate or project approval. See the company’s Quality Policy for its published policy.
Source Alloy 20 Plates from Champak Industries
Champak Industries’ company profile records its establishment in Mumbai in 1978 and its stockist, import and export activities. The page lists Alloy 20 in coil, plate, sheet and weld wire, so plate and matching weld wire can be requested in one enquiry, along with the other high nickel alloy plates. Submit the complete material and inspection specification with your enquiry.
What Determines the Alloy 20 Plate Quotation?
Nickel and copper prices, thickness, plate size, quantity, specification, required brand or source, cutting, testing and documentation all affect the quotation. Include the destination and packing requirements, and say whether pricing is needed per kilogram, per plate or per finished piece.
Packing, Dispatch and Export Requirements
Give the delivery address, required date and unloading constraints. Specify protective packing that keeps the plate away from carbon-steel contamination, piece identification and handling needs. For export orders, include the destination port, delivery terms and document list.
Alloy 20 Plates: Frequently Asked Questions
01What is the UNS number for Alloy 20?
Alloy 20 is UNS N08020, also identified as W.Nr. 2.4660. It is a niobium-stabilized nickel-iron-chromium alloy with molybdenum and copper.
02Is Alloy 20 the same as Carpenter 20Cb-3?
20Cb-3® is Carpenter Technology’s trade name for its N08020 alloy. Generic Alloy 20 plate meets the same UNS grade but is not automatically that brand, so name the brand if your project requires it.
03Which specification should I state for Alloy 20 plate?
State ASTM B463 or ASME SB463 with UNS N08020 and the required edition. B366 is for fittings and B473 is for bar and wire.
04Why is Alloy 20 used for sulfuric acid?
Its nickel, chromium, molybdenum and copper content gives good resistance across many sulfuric acid concentrations and temperatures. Check corrosion data for your exact concentration, temperature and contaminants.
05When should Alloy 20 replace 316L stainless steel?
When 316L corrodes too quickly in sulfuric acid or suffers chloride stress corrosion cracking. The higher nickel content gives much better resistance to that cracking.
06Which plate sizes can I order?
This page does not publish a size range. Send the thickness, width, length and quantity, or a drawing for cut pieces, for availability and a quotation.
07Can Alloy 20 plate be welded without post-weld heat treatment?
Usually yes. Niobium stabilization and low carbon limit intergranular attack at welds. Use a qualified procedure and a matching filler such as AWS ER320LR.
08Are the properties on this page test results for the plate supplied?
No. They are reference values. Request the heat-specific inspection certificate and any additional tests you need.
09Can I order Alloy 20 weld wire with the plate?
Yes. The original page lists Alloy 20 weld wire as well as coil, plate and sheet. Include the wire size and specification in the same enquiry.
10How do I get a price and delivery date?
Send the specification, sizes, quantity, cutting, inspection requirements, destination and required date through the enquiry form below, by WhatsApp or by phone.