Alloy 20
UNS N08020 · Corrosion-resistant Ni/Fe-Cr-Mo alloy · Product-specific technical reference.
Alloy 20 (N08020) is included here as a material reference. Evaluate acid concentration, temperature, oxidising/reducing contaminants, chlorides and fabrication. No alloy is a universal upgrade across all media.
Scope: Numerical limits below apply only to the named source, product form and condition. They are not measured results, design allowable stresses or guarantees for every product with this UNS. Acceptance follows the purchase order and applicable design/product standards.
1. Selected Chemical Requirements
Basis: ASTM B729-20, Table 1. Values are mass %. This selected-element table does not replace the complete source table and footnotes.
| Element | Requirement, mass % |
|---|---|
| C | ≤0.07 |
| Mn | ≤2.00 |
| P | ≤0.045 |
| S | ≤0.035 |
| Si | ≤1.00 |
| Cr | 19.0–21.0 |
| Ni | 32.0–38.0 |
| Mo | 2.0–3.0 |
| Cu | 3.0–4.0 |
| Fe | balance |
| Nb+Ta | 8×C–1.00 |
Check required minor/combined elements, heat/product-analysis rules and footnotes in the ordered edition. An element not listed here does not imply zero content or absence of a standard requirement.
2. Mechanical Requirements and Delivery Condition
Basis: ASTM B729-20, Table 2. Published room-temperature minima. The source MPa and ksi values are shown separately; do not combine unit systems when assessing an order.
| Product / condition / size | Tensile, MPa (ksi) | 0.2% proof / yield, MPa (ksi) | Elongation, % |
|---|---|---|---|
| Stabilised annealed | ≥550 (80) | ≥240 (35) | ≥30 |
Check the governing unit-system statement in the ordered edition. Source ksi values are retained beside the published MPa conversion. Converter-size provisions can differ. These are room-temperature acceptance values, not elevated-temperature design allowables.
3. Designation References
UNS N08020 is the material identifier used here. Cross-system names below are comparison candidates only. EN, JIS and GB/T grades can differ in chemistry, form, condition and testing; substitution requires a technical comparison and project-required approval.
| UNS | EN / DIN | EN name | JIS | GB / ISC |
|---|---|---|---|---|
| N08020 | 2.4660 | NiCr20CuMo | — | NS1403 / NS143 (legacy) |
These are recorded designation references, not a certification of equivalence. A dash means no confirmed entry is supplied. A common UNS number or commercial name does not establish branded origin.
4. Fabrication and Service Considerations
Evaluate acid concentration, temperature, oxidising/reducing contaminants, chlorides and fabrication. No alloy is a universal upgrade across all media.
Fabrication and heat treatment depend on the actual alloy and product standard. Age-hardenable alloys are not always supplied as fully annealed corrosion-resistant products. Review welding, post-fabrication treatment and environmental cracking separately; high nickel is not blanket sour-service approval.
5. Product Standards and Ordering Basis
Use the named ASTM B product specification and its applicable general requirements. B163 is for condenser/heat-exchanger tube; B637 and B865 are bar/forging-related specifications, not general seamless pipe specifications. Verify grade coverage and edition before applying any alternative.
State grade/UNS, form, route, specification/edition, OD/wall/length, condition, examination and documents. ASME SA/SB acceptance and design-code permission require separate checks. EN 10204 type 3.1 is an inspection document, not independent product approval. Chemical and mechanical tests can use different heat/lot sampling bases.
6. Typical Applications
Chemical-process duties supported by representative corrosion data.
These are examples, not a service-envelope approval. Confirm medium, concentration, temperature, pressure, flow/stagnation, deposits, crevices, stress and fabrication condition.
7. Product Enquiries and Related Pages
Forms, sizes, availability and certification are confirmed in the written quotation. Send an enquiry with the actual specification and service requirements.
Reference review: 30 October 2026. Editions identify the sources used; they do not assert that all named editions remain active or that alternative standards have identical requirements.