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Alloy 400 Stainless Steel

Penn Stainless inventory now includes Alloy 400 (UNS N04400) in sheet, sheet coil, plate, round bar, processed flat bar and tubular products.


General Properties

Alloy 400 (UNS N04400) is a ductile nickel-copper alloy with resistance to a variety of corrosive conditions. The alloy is most frequently specified in environments ranging from mildly oxidizing through neutral, and in moderately reducing conditions. An additional application area of the material is in marine environments and other nonoxidizing chloride solutions.

The alloy has a long history of use as a corrosion resistant material, dating back to the early twentieth century when it was developed as an attempt to use a high copper content nickel ore. The nickel and copper contents of the ore were in the approximate ratio which is now formally specified for the alloy.

As with commercially pure nickel, Alloy 400 is low in strength in the annealed condition. For this reason, a variety of tempers are used which have the effect of increasing the strength level of the material.


  •  Marine and chemical processing equipment
  • Valves, pumps, propeller shafts
  • Marine fixtures and fasteners
  • Gasoline and fresh water tanks
  • Process vessels and piping
  • Heat exchangers



UNS: UNS N04400

ASTM:  B 127



Corrosion Resistance

  • more corrosion resistant than commercially pure Nickel (UNS N02200) under reducing conditions
  • more resistant than refined copper alloys under oxidizing conditions.
  • may be considered for use in moderately reducing acids, neutral or alkaline solutions
  • resistant to most alkalies, salts, organic substances and atmospheric conditions.
  • considered for cooler alkaline caustic conditions, although high temperature, high stress and high concentrations of caustic have produced caustic stress corrosion cracking in the material.
  • used in reducing acids like sulfuric and hydrochloric, especially in the absence of aeration and oxidizing species.



Heat Treatment

  • anneal cycle is typically in the 1400° to 1800°F (760° to 980°C) range for short times at temperature.
  • annealing should be done in an atmosphere as free of sulfur compounds as possible since sulfur will embrittle the material in extended exposure time at the anneal temperature range.
  • low temperature stress relief may be conducted on cold deformed material by heating to approximately 575°F (300°C) for 1 to 3 hours.
  • large percentage of alloy is put into service without final heat treatment. This is done to increase the strength of the material.

Cold forming

  • exhibits excellent cold forming characteristics normally associated with chromium nickel stainless steels.
  • has a lower work hardening rate than Types 301/ 304 stainless steel
  • can be used in multiple draw forming operations where relatively large amounts of deformation occur between anneals.


  • may be joined by a variety of processes including gas tungsten-arc, gas metal-arc and shielded metal-arc processes.
  • cleaning of the joint area is necessary to avoid embrittlement from such sources as lubricants and paints.
  • material must be free of scale for best welding. Welding procedures for Alloy 400 are similar to those used for austenitic stainless steels.
  • Neither preheating nor post-weld heat treatment are generally required.


C Mn P S Si Al Ni + Co Cu Fe
0.10 0.50 0.005 0.005 0.25 0.02 Balance* 32.0 1.0

Mechanical Properties

Room Temperature:

Yield Strength Ultimate Tensile Strength Elongation percent in 2″ Elastic Modules (E)
psi (Mpa) psi (MPa) (51 mm) psi (MPa)
35,000 (240) 75,000 (520) 45 26 x 106 (180

Hot Rolled:

Yield Strength Ultimate Tensile Strength Elongation percent in 2″ Elastic Modules (E)
psi (Mpa) psi (MPa) (51 mm) psi (MPa)
45,000 (310) 80,000 (550) 30 26 x 106 (180)

Short Time Elevated Temperature:

Test Temperature 0.2% Offset Yield Strength Ultimate Tensile Strength Percent Elongation
°F °C psi (MPa) psi (MPa)
70 (21) 31,000 (215) 82,000 (565) 48
200 (93) 30,000 (205) 80,000 (550) 47
400 (204) 26,000 (180) 75,000 (520) 45
600 (316) 25,000 (175) 73,000 (505) 46
800 (427) 23,000 (160) 70,000 (480) 48
1000 (538) 21,000 (145) 53,000 (370) 40

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