Alloy 20
Alloy 20 is a nickel-iron-chromium alloy containing molybdenum and copper. It was developed for resistance to sulfuric-acid service and is widely used where conventional stainless steels do not provide sufficient corrosion resistance.
Alloy 20 Information
Alloy 20 is a nickel-iron-chromium alloy containing molybdenum and copper. It was developed for resistance to sulfuric-acid service and is widely used where conventional stainless steels do not provide sufficient corrosion resistance.
Metallic winding and compatible ring components where service conditions are suitable.
| UNS Number | N08020 |
|---|---|
| Common Name | Carpenter 20 / Alloy 20 |
| Material Type | Ni-Fe-Cr-Mo-Cu corrosion-resistant alloy |
| Common / Applicable Specification | ASTM B463 (plate/sheet/strip) |
| Typical Gasket Use | Metallic winding and compatible ring components where service conditions are suitable. |
Alloy 20 Chemical Composition
Reference composition limits are shown below. Exact requirements should be confirmed against the applicable product specification and certified material documentation.
| Element / Constituent | Symbol | Composition / Information |
|---|---|---|
| Carbon | C | 0.07 max. |
| Manganese | Mn | 2.00 max. |
| Silicon | Si | 1.00 max. |
| Chromium | Cr | 19.00–21.00 |
| Nickel | Ni | 32.00–38.00 |
| Molybdenum | Mo | 2.00–3.00 |
| Copper | Cu | 3.00–4.00 |
| Niobium + Tantalum | Nb+Ta | 8×C min.; 1.00 max. |
| Iron | Fe | Balance |
Alloy 20 Mechanical Properties
Reference room-temperature properties are shown for a commonly supplied condition. Exact requirements depend on product form, size, heat treatment and governing specification.
| Property | Reference Value | Unit / Basis |
|---|---|---|
| Tensile Strength | 551 min. | MPa |
| 0.2% Offset Yield Strength | 241 min. | MPa |
| Elongation | 30 min. | % |
Values shown are engineering reference data, not universal design allowables. Final procurement and design must use the governing specification, exact product form/condition and certified material test documentation.
Alloy 20 Physical & Service Information
Reference physical properties and service considerations relevant to material selection for Spiral Wound Gaskets.
| Density | Approx. 8.1 g/cm³ |
|---|---|
| Structure | Austenitic |
| Corrosion Behaviour | Especially useful in sulfuric-acid and mixed-acid environments, subject to concentration and temperature. |
| Heat Treatment | Normally solution annealed. |
| Service Selection | Confirm compatibility with acid concentration, contaminants, temperature and gasket filler. |
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