The Home of HASTELLOY® and HAYNES® alloys

Principle Features

High Strength and Resistance to High-Temperature Corrosion

HAYNES® 556® alloy (UNS # R30556) is an iron-nickel-chromium-cobalt alloy that combines effective resistance to sulfidizing, carburizing and chlorine-bearing environments at high temperatures with good oxidation resistance, fabricability, and excellent high-temperature strength. It has also been found to resist corrosion by molten chloride salts and other salts, and is resistant to corrosion from molten zinc.

Ease of Fabrication

HAYNES 556 alloy has excellent forming and welding characteristics. It may be forged or otherwise hot-worked, providing that it is held at 2150°F (1175°C) for a time sufficient to bring the entire piece to temperature. As a consequence of its good ductility, 556 alloy is also readily formed by cold working. All hot- or cold-worked parts should be annealed and rapidly cooled in order to restore the best balance of properties.

The alloy can be welded by a variety of techniques, including gas tungsten arc (GTAW), gas metal arc (GMAW), shielded metal arc (coated electrode), and resistance welding.


HAYNES 556 alloy is furnished in the solution heat-treated condition, unless otherwise specified. The alloy is normally solution heat-treated at 2150°F (1175°C) and rapidly cooled or water-quenched for optimum properties. Heat treatments at temperatures lower than the solution heat-treating temperature may cause precipitation of secondary phases.

Available in Practical Product Forms

HAYNES 556 alloy is available in the form of plate, sheet, strip, billet, bar, wire, pipe and tubing.

Applicable Specifications

HAYNES 556 alloy is covered by ASME Section VIII, Division 1, up to 1650°F (900°C) and ASME Section I, (Code Case 2010) up to 1200°F (650°C). ASTM specifications include B-435 (plate/sheet), B-572 (rod/bar), B-619 (welded pipe), B-622 (seamless pipe and tubing), and B-626 (welded tubing). AMS specifications are AMS 5874 (sheet/strip/plate), AMS 5877 (bar/forgings) and AMS 5831 (wire). 556 weld wire is covered by AWS specification A5.9 (ER3556). The UNS number for HAYNES 556 alloy is R30556.


HAYNES 556 alloy combines properties which make it highly useful for service at elevated-temperature in moderately to severely corrosive environments. Applications can include tubing and structural members in municipal and industrial waste incinerators, rotary calciners and kilns for minerals processing, and non-rotating components in land-based gas turbines burning low-grade fuels.

In the chemical process industry, 556 alloy is used for applications in rotary calciners, carbon regenerators, and in processes involving high-sulfur petroleum feedstocks.

In the metallurgical process industry, 556 alloy is widely used for hot-dip galvanizing fixtures, spinners and baskets, and for high speed furnace fans. 556 alloy is also employed in air preheaters of diesel engines, the inner covers of coil annealing furnaces, and in various high-temperature applications in the aerospace industry.

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