Alloy 20 (UNS N08020)
Alloy 20 (UNS N08020) — Designed for sulphuric acid service.
| UNS number | N08020 |
| Material family | Nickel-iron-chromium |
| Product specifications | B462, B366, B729 |
| Density (typical) | 8.08 g/cm³ (8080 kg/m³) |
| Weight of 6" Sch 40 pipe | 29.09 kg/m |
Specifications by product form
One alloy is ordered under different ASTM/ASME numbers depending on form: forged flanges and fittings, wrought buttweld fittings, and pipe or tube. For Alloy 20 the usual specifications are B462, B366, B729. Quote both the specification and the UNS number on purchase orders to avoid ambiguity.
Chemical and mechanical limits differ between these specifications — always check the edition of the standard named on your order and the mill test certificate.
Chemical composition & mechanical properties
| Property | Alloy 20 |
|---|---|
| Family | Nickel-iron-chromium |
| UNS | N08020 |
| EN / W.Nr | 2.4660 NiCr20CuMo |
| Basis spec | ASTM B462 |
| Density g/cm³ | 8.08 |
| Chemical composition, % | |
| C | 0.07 |
| Mn | 2.0 |
| P | 0.045 |
| S | 0.035 |
| Si | 1.0 |
| Cr | 19.0–21.0 |
| Ni | 32.0–38.0 |
| Mo | 2.0–3.0 |
| Cu | 3.0–4.0 |
| Nb | 8×C–1.00 |
| Mechanical properties (min) | |
| Tensile strength | 551 MPa (80 ksi) |
| Yield strength (0.2%) | 241 MPa (35 ksi) |
| Elongation | 30% |
| Hardness (max) | – |
| PREN (min, from spec) | 25.6 |
Single values are maximums; ranges are min–max; "bal" = balance. Limits are typical of the basis specification for that product form — forgings, pipe and fittings specifications differ slightly. Always check the exact specification, edition and the mill test certificate.
Frequently asked questions
What is the UNS number of Alloy 20?
N08020.
Which ASTM specifications cover Alloy 20?
B462, B366, B729.
What is the density of Alloy 20?
About 8.08 g/cm³ (8080 kg/m³), used for weight calculations.
Last updated 2026-11-02