Nickel Alloy 690 (UNS N06690)

Topics Covered

Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Manufacturing Process


Alloy 690 is a high-chromium nickel alloy that exhibits excellent resistance to many corrosive aqueous media and high temperature environments. It has good fabrication characteristics, metallurgical stability and high strength.

However, the alloy shows excellent resistance to stress-corrosion cracking and low corrosion rates under various high-temperature solutions.

The following datasheet will provide more details about alloy 690.

Chemical Composition

The following table shows the chemical composition of alloy 690.

Element Content (%)
Nickel, Ni ≥58
Chromium, Cr 27-31
Iron, Fe 7-11
Copper, Cu 0.5
Manganese, Mn ≤0.5
Silicon, Si ≤0.5
Sulfur, S ≤0.15
Carbon, C ≤0.05

Physical Properties

The physical properties of alloy 690 are outlined in the following table.

Properties Metric Imperial
Density 8.19 g/cm³ 0.296 lb/in³

Mechanical Properties

The mechanical properties of alloy 690 are outlined in the following table.

Properties Metric Imperial
Tensile strength 724 MPa 105000 psi
Yield strength (@strain 0.2%) 348 MPa 50500 psi
Modulus of elasticity 211 GPa 30600 ksi
Shear modulus 81.8 GPa 11900 ksi
Poisson’s ratio 0.289 0.289
Elongation at break 41% 41%

Thermal Properties

The thermal properties of alloy 690 are given in the following table.

Properties Metric Imperial
Thermal expansion coefficient (@24-100°C/75.2-212°F) 14.06 µm/m°C 7.8 µin/in°F
Thermal conductivity 13.5 W/mK 93.7 BTU in/hr.ft².°F

Manufacturing Process

Alloy 690 is readily fabricated using conventional techniques used for high-nickel alloys. This alloy is not hardenable by heat treatment, and it is normally used in the annealed condition.

It exhibits excellent weldability, and it can be welded using filler metals and welding electrode. The temperature range for heavy hot forming of alloy 690 is 1040 to 1230°C (1900 to 2250°F). Light forming can be done at temperatures down to 870°C (1600°F).


The following are some of the major applications of alloy 690:

  • Tail-gas reheaters used in nitric acid production
  • Coal-gasification units
  • Glass vitrification equipment for radioactive waste disposal
  • Incinerators
  • Furnaces for petrochemical processing
  • Burners and ducts for processing sulfuric acid

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