Incoloy® alloy 825

Sandmeyer Steel Company stocks Incoloy® alloy 825 nickel alloy plate in thicknesses from .1875" (4.8mm) through 2.00" (50.8mm) for corrosion resistant applications in the air pollution control, chemical and petrochemical, food processing, nuclear, offshore oil and gas production, ore processing, petroleum refining, steel pickling and waste disposal industries.

Available thicknesses for Incoloy® alloy 825:

Incoloy® alloy 825 (UNS N08825) is an austenitic nickel-iron-chromium alloy with additions of molybdenum, copper and titanium. It was developed to provide exceptional corrosion resistance in both oxidizing and reducing environments. This nickel alloy is resistant to chloride stress-corrosion cracking and pitting. The addition of titanium stabilizes Incoloy® alloy 825 against sensitization in the as-welded condition making the alloy resistant to intergranular attack after exposure to temperatures in a range that would sensitize un-stabilized stainless steels. The fabrication of Incoloy® alloy 825 is typical of nickel-base alloys, with material being readily formable and weldable by a variety of techniques.

General Properties

Incoloy® alloy 825 (UNS N08825) is an austenitic nickel-iron-chromium alloy with additions of molybdenum, copper and titanium. It was developed to provide exceptional resistance to numerous corrosive environments, both oxidizing and reducing.

The nickel content of Incoloy® alloy 825 makes it resistant to chloride stress-corrosion cracking, and combined with molybdenum and copper, provides substantially improved corrosion resistance in reducing environments when compared to conventional austenitic stainless steels. The chromium and molybdenum content of Incoloy® alloy 825 provides resistance to chloride pitting, as well as resistance to a variety of oxidizing atmospheres. The addition of titanium stabilizes the alloy against sensitization in the as-welded condition. This stabilization makes Incoloy® alloy 825 resistant to intergranular attack after exposure in the temperature range which would typically sensitize un-stabilized stainless steels.

Incoloy® alloy 825 is resistant to corrosion in a wide variety of process environments including sulfuric, sulfurous, phosphoric, nitric, hydrofluoric and organic acids and alkalis such as sodium or potassium hydroxide, and acidic chloride solutions.

The fabrication of Incoloy® alloy 825 is typical of nickel-base alloys, with material readily formable and weldable by a variety of techniques.

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Chemical Analysis

Typical Values (Weight %)

Mechanical Properties

Typical Room Temperature Mechanical Properties, Mill Annealed

Incoloy® alloy 825 has good mechanical properties from cryogenic to moderately high temperatures. Exposure to temperatures above 1000°F (540°C) can result in changes to the microstructure that will significantly lower ductility and impact strength. For that reason, Incoloy® alloy 825 should not be utilized at temperatures where creep-rupture properties are design factors. The alloy can be strengthened substantially by cold work. Incoloy® alloy 825 has good impact strength at room temperature, and retains it’s strength at cryogenic temperatures.

Table 6 - Charpy Keyhole Impact Strength of Plate

Corrosion Resistance

The most outstanding attribute of Incoloy® alloy 825 is its excellent corrosion resistance. In both oxidizing and reducing environments, the alloy resists general corrosion, pitting, crevice corrosion, intergranular corrosion and chloride stress-corrosion cracking.

Resistance to Laboratory Sulfuric Acid Solutions

Stress-Corrosion Cracking Resistance

The high nickel content of Incoloy® alloy 825 provides superb resistance to chloride stress-corrosion cracking. However, in the extremely severe boiling magnesium chloride test, the alloy will crack after long exposure in a percentage of samples. Incoloy® alloy 825 performs much better in less severe laboratory tests. The following table summarizes the alloy's performance.

Resistance to Chloride Stress Corrosion Cracking

Mixed – A portion of the samples tested failed in the 2000 hours of test. This is an indication of a high level of resistance.

Pitting Resistance

The chromium and molybdenum content of Incoloy® alloy 825 provides a high level of resistance to chloride pitting. For this reason the alloy can be utilized in high chloride environments such as seawater. It can be used primarily in applications where some pitting can be tolerated. It is superior to conventional stainless steels such as 316L, however, in seawater applications Incoloy® alloy 825 does not provide the same levels of resistance as SSC-6MO (UNS N08367) or Alloy 625 (UNS N06625).

Crevice Corrosion Resistance

Resistance to Chloride Pitting and Crevice Corrosion

*ASTM Procedure G-48, 10% Ferric Chloride

NOTE: The information and data in this product data sheet are accurate to the best of our knowledge and belief, but are intended for informational purposes only, and may be revised at any time without notice. Applications suggested for the materials are described only to help readers make their own evaluations and decisions, and are neither guarantees nor to be construed as express or implied warranties of suitability for these or other applications. Stainless Steel, Nickel Alloy and Titanium products are classified as sheet if the thickness of the metals is less than 3/16” (4.7mm). If the thickness of the metal is 3/16” (4.7mm) or more, then it is considered a plate.

Incoloy® and Inconel® are registered trademarks of Special Metals Corporation.