HAYNES® 556® alloy for High-temperature Chemical Processes Tech Brief

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For High-Temperature Chemical Processes

Chemical Processes and Petrochemical Industry Applications can involve some of the most corrosive conditions known. This normally poses quite difficult material problems in designing long-lasting plant equipment. For those particular processes involving corrosive conditions coupled with high-temperature, such as tail gas burners, sulfuric acid recovery facilities, and ethylene dichloride crackers, the need for an outstanding material is even more critical.

HAYNES® 556® alloy has the best combination of strength, resistance to all major forms of high-temperature corrosion, and ease of fabrication of any available commercial alloy. It is suited for long-term service at temperatures from 800°F to 2000°F, and is capable of out-performing stainless steels, nickel-chromium alloys, and iron-nickel-chromium materials by as much as a factor of ten. The 556 alloy is also covered by ASME Boiler Code Case No. 2010 for pressurized applications.

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

Corrosion Attack for 215 Hour Exposure in a Highly-Sulfidizing, Reducing Gas Environment at 1400°F

(Ar-5%H2-5%CO-1%CO2-0.15%H2S)
Alloy Average Metal Affected
556® 3.8
310 9.1
800H 11.2
625 12.6
600 >21.7
X >29.5
601 >29.5

Comparative Stress Rupture Life (Hours)
Alloy 1600°F/4.5 ksi 1800°F/2.0 ksi
556® 29,000 11,000
625 14,000 2,400
X 5,900 2,800
601 1,200 1,000
800H 1,200 920
600 280 580
316 240 130

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, superheaters, 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 pulp 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