General Description

Inconel 690 has the highest chromium content (29% Cr) among nickel alloys suitable for fabrication of pressure equipment, which confers exceptional resistance to oxidizing media. It is used for hot sulfuric acid, nitric acid, and nitric/ hydrofluoric acid mixtures, as well as for oxidizing salts. The high chromium content also improves resistance in hot sulfidizing environments.

Inconel 690 has good resistance to oxidizing chemicals, such as nitric acid, and to sulfur-containing gases at high temperature. Inconel 690 has a superior stress cracking resistance than Inconel 600 in steam generation nuclear reactors for piping, separators and weldments.

Applications involving nitric acid or nitric-plus-hydrochloric acid. Examples are tail-gas reheaters used in production of nitric acid and steam-heating coils in nitric- plus-hydrochloric acid solutions used for pickling stainless steels and reprocessing nuclear fuels. Inconel 690 is also useful for hightemperature service in gases containing sulfur.

Chemical Composition

Grade Ni% Cr% Fe% Ti% Mn% Si% C% Cu% P% S% Cu% RE%
Inconel 690 Min 58 27-31 7-11 Max 0.5 Max 0.5 Max 0.5 Max 0.05 Max 0.5 Max 0.030 Max 0.015 Max 0.5 Max 0.1


Grade UNS Werkstoff Nr.
Inconel 690 N06690 2.4642

Physical Properties

Grade Density Melting Point
Inconel 690 8.2 g/cm3 1340°C-1377 °C

Mechanical Properties

Alloy Tensile Strength Yield Strength Elongation Brinell Hardness (HB)
Inconel 690 Annealed >580 MPa >260 MPa 30% 150-240

Size Range

Inconel 690 wire, bar are available.

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