Alloy 20
Material
Alloy 20, UNS N08020, NS1403, W.Nr. 2.4660
Overview
Alloy 20 (UNS N08020) is an iron-based, low carbon, niobium stabilized superaustenitic Ni-Fe-Cr alloy with alloying addition of copper and molybdenum.
Alloy 20 has excellent corrosion resistance in chemical environments containing sulfuric acid, and useful resistance to environments containing chlorides, nitric acid, and phosphoric acid. Alloy 20 has essentially the same resistance to aqueous corrosion as those for alloy 825.
Alloy 20 has been applied economically in many areas where other materials may provide the necessary corrosion resistance, but are either higher in initial cost or more expensive to install and maintain. Important advantages of alloy 20 are its excellent mechanical properties and comparative ease of fabrication. The presence of Niobium in the alloy minimizes the precipitation of carbides in heat-affected zones during welding so that assemblies can usually be placed in service in the as-welded condition.
Application
Alloy 20 is used in a wide variety of applications up to temperatures of approximately 500 °C (930 °F).
Typical applications are:
Equipment for the manufacture of sulphuric acid and for processes based on sulphuric acid
Extraction columns in the production of amines and the processing of pharmaceuticals
Production of plastics and synthetic fiber
Equipment for food processing to protect against contamination
Mixing tanks, heat exchangers, process piping, pickling equipment
Chemical composition
| Material | Fe | Ni | Cr | Cu | Mo | Nb+Ta |
|---|---|---|---|---|---|---|
| Alloy 20 | Balance | 32.0-38.0 | 19.0-21.0 | 3.0-4.0 | 2.0-3.0 | 8 x C -1.0 |
| Material | C | Mn | Si | P | P | |
| Alloy 20 | ≤0.07 | ≤0.20 | ≤0.10 | ≤0.045 | ≤0.035 |
Mechanical property
Alloy 20 tube and pipe shall be furnished in the stabilized-annealed condition
| Material | Tensile strength ksi (MPa) |
Yield strength at 0.2 offset ksi (MPa) |
Elongation in 2” % min. |
|---|---|---|---|
| Alloy 20 | ≥80 (550) | ≥35 (240) | ≥30 |
Microstructure
Alloy 20 has a face-centred cubic structure. The balanced chemical composition and optimum annealing temperature promote the formation of niobium carbides and ensure that the corrosion resistance is not impaired by sensitization.
Available Process
Cold worked and bright annealed
Cold worked, bright annealed, polished (MP, EP etc.)
Common Tests
- ◎ Chemical composition
- ◎ Tension
- ◎ Hardness
- ◎ Flaring
- ◎ Flange
- ◎ Flattening
- ◎ Micro structure
- ◎ Hydrostatic
- ◎ NDT
- ◎ Intergranular Corrosion
- ◎ Surface condition
- ◎ Shape and dimension
- ◎ Positive Material Identification
Product forms
Capillary tube
- ◎ OD 0.30 ~ 3.0 mm
- ◎ WT 0.05 ~ 0.5 mm
Precision seamless tube
- ◎ OD 3.0 ~ 89 mm
- ◎ WT 0.10 ~ 10.0 mm
HP / UHP BA+ tube
- ◎ OD 3.0 ~ 76 mm
- ◎ WT 0.10 ~ 10.0 mm
Service
- ◎ Precision cutting
- ◎ Tube surface treatment, like ID surface super mirror polishing, best level could reach Ra0.0015um
- ◎ Tube deep processing, like coiling, bending, end forming, body forming, laser processing, various needles processing, built to drawing and sample, etc.