Alloy 400 (UNS N04400)


Alloy 400 is a nickel-copper single-phase alloy most commonly supplied in hot worked and annealed condition. Although the grade can be tempered or cold worked to increase its properties, in its standard annealed condition it is easy to form and fabricate with no requirements for additional heat treatments to re-balance the alloy. It retains excellent mechanical properties at sub-zero temperatures. Strength and hardness increase with only a slight loss of ductility and impact resistance.


Alloy 400 possesses excellent corrosion resistance to many reducing media. It can be used in contact with fluorine, hydrofluoric acid, hydrogen fluoride or their derivatives – its resistance to hydrofluoric acid has been demonstrated in all concentrations up to the boiling point. It is also resistant to many forms of sulfuric and hydrochloric acids under reducing conditions and it also performs well in seawater. Alloy 400 is resistant to stress corrosion cracking and pitting in most fresh and industrial waters. It is therefore widely used in marine engineering, chemical and hydrocarbon processing equipment, valves, pumps, shafts, fittings, fasteners, and heat exchangers.

Key Features:

  • Excellent corrosion resistance
  • Retains excellent tensile strength and toughness down to cryogenic temperatures
  • Highly resistant to hydrofluoric acid, and resistant to sulphuric and hydrochloric acids under reducing conditions
  • Resistant to chloride stress corrosion, and exhibits very low corrosion rates in flowing seawater
  • ASME Approval for Pressure Vessel application


  • Process industry applications in sulphuric acid, hydrochloric acid and fatty acid production, hydrofluoric & fluorosilicic acid processes
  • Marine industry and shipbuilding components such as propellers, shafts, fasteners
  • Oil & Gas industry pumps, valves, crude petroleum stills and process vessels
  • Heat exchanger plates
  • Electrical and electronic components
  • Boiler feedwater heaters, de-aerating heaters

Chemical Composition:

Cr Ni Mo Co Nb (+Ta) Ti V W Cu C Mn N Si P S Fe Al
Min 63.00 28.00
Max 34.00 0.30 2.00 0.50 0.024 2.50

Mechanical Properties:

Hot Worked & Annealed Cold Worked & Stress Relieved
0.2% Proof Stress 172 N/mm2 24.9 ksi 483 - 690 N/mm2 70 – 100 ksi
1.0% Proof Stress 195 N/mm2 28.3 ksi
Tensile Strength 483 N/mm2 70 ksi 621 - 862 N/mm2 90 -125 ksi
Elongation, 5.65√S0 and 4D 35% 20%
Reduction of Area 60% 60%
Hardness 110 – 132 HBN 35 HRC max
Impact Strength (Room Temp) 160J av (150J min) 160J av (150J min)


  1. Testing shall be carried out in accordance with ASTM A370 or EN ISO 10002-1 (tensile), EN ISO 6506-1 (hardness)
  2. Minimum properties quoted (tested at room temperature in a longitudinal direction)
  3. Testing performed on each melt of material per heat treatment batch

Physical Properties:

Density (Kg/m3) 8830
Magnetic Permeability (20°C) Could show magnetism as Curie temperature is close to room temperature
Young’s Modulus (kN/mm2) 179
Specific Electrical Resistance, 20°C (µΩ-m) 0.51
Mean coefficient of thermal expansion, 20-100°C (m/m/degC) 14.1 x 10-6
Specific Heat, 20°C (J/kg.K) 419
Thermal conductivity, 20°C (W/m.K) 21.8
Curie Temperature (°C) 21 - 49


Datasheet - NA-Alloy 400

Datasheet - NA-Alloy 400