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HAYNES® Alloys

For Fossil-Fuel-Fired Energy Systems

Many power plant facilities today are burning difficult to handle fuels such as high-sulfur coal and fuel oil.

Difficult to handle, in as much as process internals are too often subject to both reducing carburizing atmospheres and sulfidizing environments which lead to early failure. This can mean frequent replacement or maintenance for components such as burner buckets, grates, tube supports, rapper bars, soot blowers, and numerous other traditional boiler internals. And, in the never fluidized bed technology facilities, in-bed tubulars and support hardware require materials which can stand up to even harsher environments.

HAYNES® 556® alloy is one of few materials to combine excellent design strength with broad spectrum resistance to most key forms of high-temperature corrosion. This resistance includes carburizing atmospheres, sulfidizing environments, chlorine-contaminated process gases and several others, proven in such demanding uses as internals in municipal waste incinerators.

556 alloy is covered by ASME Boiler Code Case No. 2010 for use to 1200°F (650°C), with extension to 1650°F (900°C) coverage soon to be proposed. It is currently in service in several boiler and fluidized-bed facilities, and on test in many others.

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 municipal and chemical waste incinerators; power plant burner buckets, cair 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.

Proposed Design Stresses For
100,000-Hour Life at 1500°F (815°C)
Alloy Stress
- mils MPa
556® 23 3.4
X 20 2.9
800HY 15 2.2
304 10 1.4
316 9 1.3

Sulfidation Resistance for 215-Hour Exposure
(Ar-5%H2-5%CO-1%CO2-0.15%H2S)
1400°F (760°C)
Alloy Maximum Metal Affected
- mils µm
556® 3.8 97
310 9.1 231
800H 11.2 284
625 12.6 320
600 21.7 551
X 29.5 749

 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 52
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

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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