Alloy 20, 2.4660, UNS N08020, Incoloy® 20 - nickel alloy

Alloy 20, 2.4660, UNS N08020, Incoloy® 20 - nickel alloy according to ASTM B 463, DIN 17750 etc.

Alloy 20, 2.4660, UNS N08020, Incoloy® 20 – description

Alloy 20 is a Fe-Ni-Cr alloy stabilised by niobium with alloying additions of copper and molybdenum. Shows very good resistance to sulphuric acid, phosphorus acid and organic acids. Usable up to about 500°C.

Applications

Mixing tanks, heat exchangers, process piping, pickling equipment, pumps, valves, fasteners and fittings in environments containing sulfuric acid mostly, but also gasoline, solvents, pharmaceuticals, food, as well as many inorganic and organic chemicals.

Physical and mechanical properties

Room temperature physical properties:

• Density: 8.08 g/cm³
• Melting temperature: 1380-1420 °C
• Magnetic Permeability: 1.002

High-temperature Coefficient of thermal expansion, from 20°C to:

• 100°C: 15.0 μm/m⋅K
• 200°C: 15.6 μm/m⋅K
• 300°C: 16.0 μm/m⋅K
• 400°C: 16.4 μm/m⋅K
• 500°C: 16.7 μm/m⋅K
• 600°C: 17.1 μm/m⋅K
• 700°C: 17.4 μm/m⋅K

Electrical resistivity:

• 20°C: 1.07 μΩ·m
• 100°C: 1.1 μΩ·m
• 200°C: 1.13 μΩ·m
• 300°C: 1.16 μΩ·m
• 400°C: 1.19 μΩ·m
• 500°C: 1.21 μΩ·m
• 600°C: 1.23 μΩ·m
• 700°C: 1.25 μΩ·m

Thermal conductivity:

• 20°C: 11.8 W/m · K
• 100°C: 12.4 W/m · K
• 200°C: 12.8 W/m · K
• 300°C: 13.2 W/m · K
• 400°C: 13.6 W/m · K
• 500°C: 14.1 W/m · K
• 600°C: 14.7 W/m · K
• 700°C: 15.2 W/m · K

Specific heat capacity:

• 20°C: 456 J/kg⋅K
• 100°C: 466 J/kg⋅K
• 200°C: 476 J/kg⋅K
• 300°C: 485 J/kg⋅K
• 400°C: 492 J/kg⋅K
• 500°C: 500 J/kg⋅K
• 600°C: 508 J/kg⋅K
• 700°C: 515 J/kg⋅K

Tensile modulus:

• 20°C: 202 GPa
• 100°C: 198 GPa
• 200°C: 192 GPa
• 300°C: 185 GPa
• 400°C: 179 GPa
• 500°C: 172 GPa
• 600°C: 164 GPa
• 700°C: 157 GPa

Tensile properties of alloy 2.4660 rods after tempering designated as F55 according to DIN 17752:2019:

• Yield strength: >240 MPa
• Tensile strength: >550 MPa
• Elongation: >40 %

Tensile properties of annealed alloy 20 steel according to ASTM A 479:

• Yield strength: >240 MPa
• Tensile strength: >550 MPa
• Elongation: >30 %
• Reduction of area: >50 %

Tensile properties of strain hardened alloy 20 steel according to ASTM A 479:

• Yield strength: >415 MPa
• Tensile strength: >620 MPa
• Elongation: >15 %
• Reduction of area: >40 %

High-temperature tensile properties of annealed VDM® Alloy 20 steel plate according to the producer:

• 20°C:
  • Yield strength: >240 MPa
  • Tensile strength: >280 MPa
• 100°C:
  • Yield strength: >210 MPa
  • Tensile strength: >250 MPa
• 200°C:
  • Yield strength: >180 MPa
  • Tensile strength: >220 MPa
• 300°C:
  • Yield strength: >160 MPa
  • Tensile strength: >200 MPa

Corrosion behaviour

Very good corrosion resistance to sulphuric, phosphoric and organic acids and to aqueous salt solutions. Adequate resistance to nitridation.

Corrosion rate in specific environments:

• Hydrochloric acid (HCl) 1%, boiling: 2.03 mm/year
• Hydrochloric acid (HCl) 2%, boiling: 5.77 mm/year
• Nitric acid (HNO₃) 65%, boiling: 0.2 mm/year
• Phosphorus pentoxide (P₂O₅) 116°C, boiling: 0.9 mm/year
• Sulfuric acid (H₂SO₄) 10%, boiling: 0.55 mm/year
• Sulfuric acid (H₂SO₄) 30%°C, at 80°C°C: 0.455 mm/year
• Sulfuric acid (H₂SO₄) 11,5% + 1.2% HCl + 1% FeCl₃ + 1% CuCl₂ (ASTM G 28B), boiling: 68 mm/year
• Sulfuric acid (H₂SO₄) 50% + 42 g/L Fe₂(SO₄)₃, boiling: 0.25 mm/year
• Acetic acid (CH₃COOH) 99%, boiling: 2.03 mm/year
• Nitric acid (HNO₃) 65%, boiling: 0.2 mm/year

Weldability

Alloy 20 has good weldability. It is included in weldability group 45 (ISO 15608, TR 20173, ASME Section IX). Brazing P-number 111 (ASME Section IX).

Selection of welding consumables for Alloy 20:

• Coated electrodes: ENiCrMo-3, ENiCrMo-13
• Filler metals: ERNiCrCoMo-1

Heat treatment, working and machining

Recommended working and heat treatment parameters:

• Hot forming:
  - 1175-760°C according to Special Metals® (Incoloy® 20)
  - 1150-900°C according to VDM® (VDM® Alloy 20)
• Heat treatment:
  - 982-1010°C according to Special Metals® (Incoloy® 20)
  - 920-960°C according to VDM® (VDM® Alloy 20)

Holding time for heating is approx. 60 minutes per 100 mm thickness. The part should be annealed after hot working and in case of cold forming above 15%.

We deliver this steel alloy as:

• Rod, bar, wire, forging according to ASTM B 462 / ASME SB-462, ASTM B 472 / ASME SB-472, ASTM B 473 / ASME SB-473, ISO 9723, ISO 9724, ISO 9725, DIN 17752-17754
• Plates, strips and sheets according to ASTM A 240 / ASME SA-240, ASTM A 480 / ASME SA-480, ASTM B 463 / ASME SB-463, ASTM B 906 / ASME SB-906, ISO 6208, DIN 17750
• Pipes according to ASTM B 729 / ASME SB-729, ASTM B 829 / ASME SB-829, ASTM B 468 / ASME SB-468, ASTM B 751 / ASME SB-751, ASTM B 464 / ASME SB-464, ASTM B 775 / ASME SB-775, ASTM B 474 / ASME SB-474, ISO 6207, DIN 17751

Replacements, equivalents and other designations:

Alloy 20, N08020, H08020, NS1403, 2.4660, NiCr20CuMo, Nicrofer® 3620 nb, VDM® Alloy 20, AN58F, FeNi35Cr20Cu4Mo2, NW8020, Haynes® 20Cb3, Haynes® 320, Phyweld® 920 SLR, AV 20 Valbruna, SCS 23, F 20 PNST, F-8417, Sanicro 32Cu, Sanicro 36 X2Cu, Incoloy® 20, Incoloy® alloy 20, Coralloy 20, NAS 335X, NTK 30AC, NTK 30A, ASTM B 471 / ASME B 471, 29Cb3, Crucible 20 Bc plus, JS Alloy 20, 20 plus alloy,