ThePipingMart Blog Grades Haynes 556 (UNS R30556) – Composition, Properties and Uses

Haynes 556 (UNS R30556) – Composition, Properties and Uses

Haynes 556

Haynes 556 is a unique metal alloy increasingly popular in many industrial applications. It is a nickel-chromium-cobalt-molybdenum alloy known for its excellent mechanical and physical properties. It is commonly used in industrial processes that require high-temperature resistance. This blog will take you through everything you need to know about Haynes556.

Haynes 556 Composition

Haynes 556’s unique composition makes it an excellent choice for high-temperature applications. It comprises 24-27% chromium, 14-17% cobalt, 5.5-9% molybdenum, and 1.5-3% titanium, with the remaining being nickel, iron, and other trace elements. The high chromium and molybdenum content makes Haynes556 highly resistant to corrosion and oxidation, while the titanium content increases its creep resistance.

Elements Content (%)
Iron, Fe 31
Chromium, Cr 22
Nickel, Ni 20
Cobalt, Co 18
Molybdenum, Mo 3
Tungsten, W 2.5
Manganese, Mn 1
Tantalum, Ta 0.6
Silicon, Si 0.4
Nitrogen, N 0.2
Aluminum, Al 0.2
Carbon, C 0.1
Lanthanum, La 0.02
Zirconium, Zr 0.02

Haynes 556 Mechanical Properties

Haynes 556 has excellent mechanical properties, making it suitable for high-temperature applications. It has a tensile strength of 1260 MPa and a yield strength of 690 Mpa. Haynes 556 maintains its strength even at high temperatures, making it an excellent choice for high-temperature applications.

Properties Metric Imperial
Tensile strength 815 MPa 118000 psi
Yield strength 410 MPa 59500 psi
Charpy impact 240 J 177 ft. lb
Elongation at break 47.70% 47.70%
Elastic modulus 205 GPa 29700 ksi

Haynes 556 Physical Properties

Haynes 556 has excellent physical properties that make it ideal for high-temperature applications. It has a density of 8.27g/cm3, a melting point of 1324°C, and a thermal conductivity of 10.85 W/m.K. Haynes 556 also has a low coefficient of thermal expansion, making it resistant to thermal shock.

Properties Metric Imperial
Density 8.23 g/cm³ 0.297 lb/in³
Melting point 1371ºC 2500ºF

Haynes 556 Equivalent

  • AMS 5831
  • AMS 5874
  • AMS 5877
  • ASTM B366
  • ASTM B435
  • ASTM B572
  • ASTM B619
  • ASTM B622
  • ASTM B626

Haynes 556 Uses

Haynes 556 is utilized in various applications, including gas turbines, heat exchangers, and petrochemical processing. Its high-temperature properties make it an excellent material for components subjected to thermal cycling or high-temperature service conditions. It is also commonly used in the aerospace industry.

Haynes 556 Corrosion Resistance

Haynes 556 has excellent corrosion resistance in various environments. Its high chromium content makes it resistant to corrosion, while the molybdenum content provides resistance against pitting and crevice attacks. Additionally, the titanium content increases its resistance to intergranular attack.

Haynes 556 Heat Treatment

Haynes 556 is a hot-worked alloy that can be annealed or aged to optimize its mechanical and physical properties. The annealing process is typically done at 1110°C and then air-cooled. The ageing process is usually done at 982°C, followed by air cooling. These processes can optimize the mechanical properties and enhance the alloy’s performance under high-temperature conditions.

Haynes 556 Machining

Haynes 556 is a high-strength, heat-resistant alloy that can be challenging to machine. However, proper machining techniques can be employed to achieve excellent results. Carbide-tipped tools are the best suited for machining Haynes 556. Low cutting speeds and high feed rates are recommended to reduce heat buildup and tool wear.

Haynes 556 Welding

Haynes 556 is ideally suited to welding processes such as TIG, MIG, and plasma arc. Proper welding procedures are required to prevent cracking and ensure optimum properties. Welding Haynes 556 requires preheating to avoid cracking and post-weld heat treatment to ensure optimum mechanical properties.


Haynes 556 is a unique alloy with excellent mechanical and physical properties, making it suitable for high-temperature applications. Its excellent corrosion resistance, Heat Treatment, Machining, and Welding processes make it an ideal choice for various industrial processes. Haynes 556 is the perfect material to consider if you have a high-temperature application.

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