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HAYNES® Alloys

For High-Temperature Pulp & Paper Process Equipment

Operating conditions in high-temperature pulp and paper production processes are among the most corrosive in industry. Super heaters and cyclone separators in Kraft recovery boilers are subjected to highly corrosive gases generated from the combustion of black liquors. Other facilities are subjected to high-temperature corrosion from process feed stocks containing sulfur-rich gases or molten salts.
HAYNES® 556® alloy combines the resistance to high-temperature corrosion required for survival in many of these hostile environments with excellent high-temperature strength - enough strength to allow for significant reduction in required section size for many types of components when compared to austenitic stainless steels or 600 or 800 alloys.
As for corrosion resistance, HAYNES 556 is designed to resist degradation from SO2 or H2S-bearing atmospheres at temperatures as high as 1800°F. It has very good resistance to molten salt environments, and is among the best materials for chlorine-contaminated oxidizing environments up to 1650°F. It also exhibits excellent resistance to carburization.

Nominal Composition

Iron: Balance
Nickel: 20
Cobalt: 18
Chromium: 22
Molybdenum: 3
Tungsten: 2.5
Tantalum: 0.6
Nitrogen: 0.2
Silicon: 0.4
Manganese: 1
Aluminum: 0.2
Carbon: 0.1
Lanthanum: 0.02
Zirconium: 0.02

Typical Tensile Properties, Plate

Test Temperature 0.2% Yield Strength Ultimate Tensile Strength Elongation
°F °C ksi MPa ksi MPa %
RT RT 55 375 116 805 51
1000 540 31 210 90 625 60
1200 650 31 210 83 575 57
1400 760 29 200 69 470 53
1600 870 28 190 49 340 69
1800 980 19 130 31 210 84
2000 1095 9 60 16 110 95

Typical Rupture Properties, Plate

Test Temperature Typical Rupture Properties: Stress Required to Produce Rupture in Hours Shown
100 h 1,000 h 10,000 h
°F °C ksi MPa ksi MPa ksi MPa
1400 760 25.0 172 17.5 121 11.9 82
1500 815 17.0 117 11.8 81 7.8 53
1600 870 11.5 79 7.5 52 4.9 34
1700 915 7.6 52 4.8 33 3.0 21
1800 980 4.8 33 3.0 21 1.9 13

Typical Room Temperature Physical Properties

Physical Property British Units Metric Units
Density 0.297 lb/in3 8.23 g/cm3
Electrical Resistivity 37.5 µohm-in 95.2 µohm-cm
Modulus of Elasticity 29.7 x 106 psi 206 GPA
Thermal Conductivity 77 Btu-in/ft2-h-°F 11.1 W/m-°C
Specific Heat 0.111 Btu/lb-°F 464 J/Kg-°C

Product Description

HAYNES 556 alloy 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 molten zinc.

HAYNES 556 alloy is highly useful for service at elevated-temperature in moderately to severely corrosive environments. Applications include tubing and structural members in waste heat recuperators, super heaters, and internals in burner buckets, air nozzles, and fluidized bed combustor heat exchangers and internals; in municipal and chemical waste incinerators; power plant burner buckets, air nozzles and fluidized bed combustor heat exchangers and internals; high-speed furnace fans, galvanizing bath hardware and brazing fixtures; and high-temperature rotary calciners and kilns. There are also additional uses in the chemical/petrochemical process and pump and paper industries.

Environmental Resistance

Oxidation in Air - Excellent at 2000°F (1095°C)

Sulfidation - Second only to Co-base alloys

Molten Chloride Salts - Equal to alloy X

Chlorination - Very good to 1650°F (900°C)

Carburization - Equal to alloy 800H

Molten Zinc - Best Available

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