HAYNES® 556
High Strength and Resistance to High-Temperature Corrosion
HAYNES® 556™
HAYNES® 556™ 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.Fabrication
HAYNES® 556 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.Applications
HAYNES® 556 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, alloy 556 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. Alloy 556 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.
Heat Treatment
HAYNES® 556 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.Welding Procedures
HAYNES® 556™ alloy is readily welded by gas tungsten arc (GTAW), gas metal arc (GMAW), shielded metal arc (coated electrode), and resistance welding techniques. Submerged arc welding is not recommended as this process is characterized by high heat input to the base metal and slow cooling of the weld. These factors can increase weld restraint and promote cracking.Base Metal Preparation
The joint surface and adjacent area should be thoroughly cleaned before welding. All grease, oil, crayon marks, sulfur compounds and other foreign matter should be removed. It is preferable, but not necessary, that the alloy be in the solution annealed condition when welded.Filler Metal Selection
Matching composition filler metal is recommended for joining alloy 556. For shielded metal-arc welding, MULTIMET® electrodes (AMS 5795) are suggested. For dissimilar metal joining of alloy 556 to nickel- or cobalt-base materials, 556 filler metal will generally be a good selection, but HASTELLOY® S (AMS 5838A) or HASTELLOY® W (AMS 5786B, 5787A) welding products may be used. For dissimilar welding to iron-base materials, 556 filler metal is recommended.Preheating, Interpass Temperatures and PostWeld Heat Treatment
Preheat is not usually required so long as base metal to be welded is above 32°F (0°C). Interpass temperatures generally should be low. Auxiliary cooling methods may be used between weld passes, as needed, providing that such methods do not introduce contaminants. Post-weld heat treatment is not normally required for 556 alloys.Specifications:
- ASME Section VIII, Division 1, up to 1650°F (900°C)
- ASME Section I, (Code Case 2010) up to 1200°F (650°C)
- AMS 5831
- AWS A5.9 ER3556
- UNS R30556
| Nominal Chemical Composition (%) | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Fe | Ni | Co | Cr | Mo | W | Ta | N | Si | Mn | Al | C | La | Zr |
| Bal | 20 | 18 | 22 | 3 | 2.5 | 0.6 | 0.2 | 0.4 | 1 | 0.2 | 0.1 | 0.02 | 0.02 |