A Comprehensive Guide to Nickel-based super alloy: Incoloy 801 (UNS N08801) & 802 (UNS N08802)

What is Incoloy 801 & 802?

• Incoloy 801: UNS N08801, also known as “Alloy 801”;
• Incoloy 802: UNS N08802, “Alloy 802”.

Very similar to Incoloy 800, both Incoloy 801 and Incoloy 802 are iron-nickel-chromium alloys. Incoloy 801 has increased titanium additions raising the tensile and rupture strength dramatically and it has exceptional resistance to polythionic acid cracking.

N08801 stainless steel is a superaustenitic (highly alloyed) stainless steel formulated for primary forming into wrought products. Cited properties are appropriate for the annealed condition. N08801 is the UNS number for this material. Alloy 801 is the common industry name.
It has a moderately low base cost among wrought superaustenitic stainless steels. In addition, it has a fairly high tensile strength and a moderately low ductility.
The graph bars on the material properties cards below compare N08801 stainless steel to: wrought superaustenitic stainless steels (top), all iron alloys (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it’s 50% of the highest, and so on.
Incoloy 802 offers competitive high-temperature strength capabilities because of its high carbon level and has been used extensively in sinter deck plate applications for handling abrasive, high-temperature environments. Yaang mainly supplies Incoloy 801 & 802 in the form of flange.

Characteristics of Incoloy 801 & 802 alloy

801 & 802 alloy is a high-temperature alloy composed of nickel, iron, chromium, and aluminum elements. Its unique characteristics make it perform well in high temperature and corrosive environments.

• 1. High temperature strength;
• 2. High creep rupture strength;
• 3. Oxidation and carburizing resistance in high temperature environment;
• 4. Good corrosion resistance in many acidic environments;
• 5. It has good tolerance to many sulfur-containing atmospheres.

Firstly, Incoloy 801 & 802 alloy has excellent corrosion resistance. It can resist the erosion of corrosive media such as acid, alkaline, and chloride and is therefore widely used in chemical, petroleum, and marine engineering fields. It can maintain the integrity and stability of its materials in both high-temperature and high-pressure environments.

Secondly, Incoloy 801 & 802 alloy has excellent high-temperature resistance. It can maintain strength and rigidity at high temperatures and is not easily deformed or melted. Therefore, it is often used to manufacture high-temperature process equipment such as high-temperature furnaces, heat exchangers, and petrochemical equipment. In addition, Incoloy 801 & 802 alloy has good mechanical properties. It has high strength and good plasticity and can withstand high stress and impact loads. This has made it widely used in aerospace, automotive, and mechanical manufacturing fields.

Finally, Incoloy 801 & 802 alloy has excellent welding performance. It can be connected through various common welding methods, such as arc welding, TIG welding, and MIG welding. This makes it more convenient and flexible in the manufacturing and maintenance process. Incoloy 801 & 802 alloy has broad application prospects in various fields due to its excellent corrosion resistance, high temperature resistance, good mechanical properties, and welding performance. It meets the needs of high temperature and corrosive environments and provides reliable performance and long-term service life.

Chemical Composition of Incoloy 801 (UNS N08801) & 802 (UNS N08802)

Element	Incoloy 801, %	Incoloy 802, %
Nickel	≥32	≥32
Chromium	≥20.5	≥21
Iron	Balance	Balance
Carbon	≤0.05	≤0.35
Aluminum	–	≥0.60
Titanium	≥1.10	≥0.70
Copper	≥0.15	–

Physical Properties of Incoloy 801 (UNS N08801) & 802 (UNS N08802)

Density	Melting Range	Specific Heat	Elastic Modulus
g/cm3	°C	J/kg. k	Gpa
8.0	1372-1400	485	200

Mechanical Properties of Incoloy 801 (UNS N08801) & 802 (UNS N08802)

Tensile Strength, min.	Yield Strength, min.	Elongation, min.	Reduction in Area, min.
Mpa	Mpa	%	%
1160	1035	15	53

*Incoloy 801 and Incoloy 802 flanges should be furnished in the conditions of oil quenched, fine grained and tempered at 426°C.

Uses of Incoloy 801 (UNS N08801) & Incoloy 802 (UNS N08802)

Incoloy 801 & 802 alloy is a nickel based alloy with excellent high temperature and corrosion resistance. It mainly comprises nickel, iron, chromium, aluminum, etc. It has good antioxidant and sulfurization resistance and can maintain stable mechanical properties at high temperatures. Incoloy 801 & 802 alloys are widely used in petrochemicals, energy, aerospace, etc.

• 1. Aerospace industry: Incoloy 801 & 802 high-temperature alloys are widely used in the production of aviation and jet engines due to their excellent high-temperature and corrosion resistance. The strength and corrosion resistance of Incoloy801 alloy in high-temperature environments makes it an ideal choice for manufacturing high-temperature components.
• 2. Energy industry: Incoloy 801 & 802 high-temperature alloys are widely used in power plants, nuclear plants, and petrochemical industries. The corrosion and oxidation resistance of Incoloy801 alloy makes it an ideal material for making chemical equipment, high-temperature pipelines, and engine components under high temperature and pressure environments.
• 3. Chemical industry: Incoloy 801 & 802 high-temperature alloys are also widely used in chemical plants, especially in high-temperature, high-pressure, and corrosive media environments. Its corrosion, strength, and oxidation resistance make it an ideal material for making chemical equipment, valves, and pipelines.
• Incoloy 801 & 802 alloys have been widely used in petrochemical, energy, aerospace, and other industries due to their excellent high-temperature and corrosion resistance, providing reliable material solutions for various industries.

Corrosion Resistance of Incoloy 801 (UNS N08801) & Incoloy 802 (UNS N08802)

Incoloy 801 & 802 have excellent corrosion resistance properties, making them suitable for harsh conditions. The presence of titanium and aluminum elements in the alloy prevents the formation of chromium carbides, which can cause intergranular corrosion. Additionally, this material is resistant to sulfate-reducing bacteria attacks in seawater environments.

Heat Treatment of Incoloy 801 (UNS N08801) & Incoloy 802 (UNS N08802)

Incoloy 801 & 802 can be heat-treated to enhance its high-temperature strength and durability. The material can be solution annealed at 1093°C before being cooled rapidly. This heat treatment ensures that the material has improved grain structure, enhancing its strength and resistance to high-temperature oxidation.

Machining of Incoloy 801 (UNS N08801) & Incoloy 802 (UNS N08802)

Incoloy 801 & 802 can be machined using conventional machining techniques. However, the material is prone to work hardening, so caution must be taken when machining it. It’s, therefore, essential to use carbide tooling, low cutting speeds, and high feed rates when machining Incoloy 801 & 802. This will reduce the chances of work hardening and prolong the life of the cutting tool.

Welding of Incoloy 801 (UNS N08801) & Incoloy 802 (UNS N08802)

Incoloy 801 & 802 can be welded using several welding techniques, including Gas Tungsten Arc Welding (GTAW/TIG), Gas Metal Arc Welding (GMAW/MIG), and Submerged-Arc-Welding (SAW). It’s, however, crucial to take special precautions when welding this material to prevent cracking, porosity, and intergranular corrosion.