Alloy 800, Alloy 800H, Alloy 800HT - Nickel Alloy

Alloy 800, Incoloy 800, Incoloy 800H, Incoloy 800HT and substitutes according to UNS, ASTM A182/SA182, JIS G 4902:2019, EN 10216-5:2021

Incoloy 800, N08810, alloy 800 – description

Alloy 800 (N08810) is a Fe-Ni-Cr alloy, designed to be leaner and cheaper alternative to Ni-Cr-Fe alloys. Nickel and Chromium improve oxidation, carburization, nitridation and chlorination resistance. alloy 800 also has Aluminum and Titanium, which serve as age-hardening components and improve sulfidation and oxidation resistance. It must be said however, that the content of Al and Ti is quite low and the alloys with higher Al content have significantly better corrosion resistance. Shouldn't be applied in temperatures exceeding 650°C.

N08810 / alloy 800H is a variant of alloy 800 that has better high-temperature mechanical properties, hence can be used at temperatures above 650°C.

N08811 / alloy 800HT is an improved variant of alloy 800 with a higher minimum amount of aluminium and titanium. It is characterised by improved high-temperature strength, heat-resistance and creep-resistance.

Applications

Alloy 800 was first introduced as a sheathing material for electric stove elements. Now it is applied in high-temperature petrochemical environments where naptha and heavy oils are cracked into component distillate parts. It can be found in nuclear engineering.

Alloy H is used in thermal processing applications and in petrochemical industry.

Alloy HT is also used in thermal processing applications and in petrochemical industry, but can operate in more severe environments.

Alloy 800 / 800H / 800HT - physical and mechanical properties

The physical and mechanical properties do not differ significantly between alloy 800, alloy 800H and alloy 800HT, especially at temperatures below 650°C. Hence, unless explicitly stated, the following parameters apply to all three alloys.

Room temperature physical and mechanical properties:

• Density: 7.94 g/cm³
• Electrical resistivity: 0.989 μΩ⋅m
• Specific heat capacity: 502 J/kg⋅K
• Magnetic permeability: 1.0092 ; 16kA/m
• Melting temperature: 1357-1385 °C
• Curie temperature: -115 °C
• Young's modulus: 193 GPA
• Hardness: 138 HRB

Electrical resistivity and temperature:

• 100°C: 0.989 μΩ⋅m
• 200°C: 1.035 μΩ⋅m
• 300°C: 1.089 μΩ⋅m
• 400°C: 1.127 μΩ⋅m
• 500°C: 1.157 μΩ⋅m
• 600°C: 1.191 μΩ⋅m
• 700°C: 1.223 μΩ⋅m
• 800°C: 1.266 μΩ⋅m
• 900°C: 1.283 μΩ⋅m
• 1000°C: 1.291 μΩ⋅m

Thermal conductivity and temperature:

• 100°C: 13 W/(m*K)
• 200°C: 14.7 W/(m*K)
• 300°C: 16.3 W/(m*K)
• 400°C: 17.9 W/(m*K)
• 500°C: 19.5 W/(m*K)
• 600°C: 21.1 W/(m*K)
• 700°C: 22.8 W/(m*K)
• 900°C: 21.1 W/(m*K)
• 1000°C: 31.9 W/(m*K)

Coefficient of thermal expansion and temperature (linear):

• 26-500°C: 16.8 *10^-6m/(m*K)
• 26-600°C: 17.1 *10^-6m/(m*K)
• 26-700°C: 17.5 *10^-6m/(m*K)
• 26-800°C: 18 *10^-6m/(m*K)

Elastic modulus and temperature:

• 100°C: 191.3 GPa
• 200°C: 184.8 GPa
• 300°C: 178.3 GPa
• 400°C: 171.6 GPa
• 500°C: 165 GPa
• 600°C: 157.7 GPa
• 700°C: 150.1 GPa
• 800°C: 141.3 GPa

Tensile strength of Incoloy 800 (for common section sezes, small sizes have better strength):

• Annealed bar: 517-690 MPa
• Hot finished bar: 552-827 MPa
• Cold drawn bar: 690-1034 MPa
• Hot rolled plate: 552-758 MPa
• Annealed plate: 517-724 MPa
• Annealed Strip: 517-690 MPa
• Hot finished tube: 517-724 MPa
• Cold drawn and annealed tube: 517-690 MPa
• Annealed wire: 552-758 MPa

Yield strength of Incoloy 800 (for common section sezes, small sizes have better strength):

• Annealed bar: 207-414 MPa
• Hot finished bar: 241-621 MPa
• Cold drawn bar: 517-862 MPa
• Hot rolled plate: 207-448 MPa
• Annealed plate: 207-414 MPa
• Annealed Strip: 207-379 MPa
• Hot finished tube: 172-414 MPa
• Cold drawn and annealed tube: 207-414 MPa
• Annealed wire: 241-448 MPa

Elongation of Incoloy 800 (for common section sezes, small sizes have smaller elongation):

• Annealed bar: 60-30%
• Hot finished bar: 50-25%
• Cold drawn bar: 30-10%
• Hot rolled plate: 50-25%
• Annealed plate: 50-30%
• Annealed strip: 50-30%
• Hot finished tube: 50-30
• Cold drawn and annealed tube: 50-30
• Annealed wire: 45-25

Stress-rupture data showing average rupture life strength for given temperature and test duration:

• Temperature 650°C:
  • T. duration 100 h: 220 MPa
  • T. duration 1000 h: 145 MPa
  • T. duration 10,000 h: 121 MPa
  • T. duration 30,000 h: 103 MPa
  • T. duration 50,000 h: 97 MPa
  • T. duration 100,000 h: 90 MPa
• Temperature 760°C:
  • T. duration 100 h: 115 MPa
  • T. duration 1000 h: 69 MPa
  • T. duration 10,000 h: 50 MPa
  • T. duration 30,000 h: 43 MPa
  • T. duration 50,000 h: 40 MPa
  • T. duration 100,000 h: 37 MPa
• Temperature 870°C:
  • T. duration 100 h: 45 MPa
  • T. duration 1000 h: 33 MPa
  • T. duration 10,000 h: 24 MPa
  • T. duration 30,000 h: 21 MPa
  • T. duration 50,000 h: 19 MPa
  • T. duration 100,000 h: 17 MPa
• Temperature 925°C:
  • T. duration 10,000 h: 13 MPa
  • T. duration 30,000 h: 11 MPa
  • T. duration 50,000 h: 10 MPa
  • T. duration 100,000 h: 8.3 MPa
• Temperature 980°C:
  • T. duration 10,000 h: 8.3 MPa
  • T. duration 30,000 h: 6.9 MPa
  • T. duration 50,000 h: 6.5 MPa
  • T. duration 100,000 h: 6.2 MPa

Charpy's impact energy of annealed plates:

• -253°C: 99 J
• -196°C: 106 J
• -78°C: 122 J
• In ambient temperature: 122 J

Corrosion behaviour

Alloy 800 has good oxidation resistance, is relatively free from stress-corrosion cracking, offers resistance to polythionic acid cracking and chloride-ion sulfide stress cracking (SSC). Applications generally at temperatures below 650°C. Alloy 800H shows improved resistance to oxidation, carburisation and nitration at temperatures above 650°C. Alloy 800 HT can be used at even higher temperatures (typically up to 925°C) due to improved high-temperature strength.

Let us analyse the corrosion resistance in the different environments. For each result, it is indicated specifically which alloy the test applies to. In most cases, however, the results can be considered representative of all three alloys.

Nitric acid HNO₃ - excellent resistance of alloy 800 at concentrations up to 70% and at temperatures up to boiling point.

Atmospheric corrosion - good resistance of alloy 800. Results of a 20 year exposure to atmosphere near the ocean at Kure Beach show that average weight loss is 27,9 mg/dm² and the average pit was less than 0.025 mm deep.

Organic acids - good resistance of all three alloys.

Sea water - good resistance.

Corrosion rates of incoloy 800 for common acids and other corrosive media (laboratory tests at 80°C):

• Acetic acid CH₃COOH, 10%: 0.0003 mm/year
• Aluminum sulfate Al₂(SO₄)₃, 5%: 0.0003 mm/year
• Ammonium chloride NH₄Cl, 5%: 0.0006 mm/year
• Ammonium hydroxide NH₄OH, 5%: 0.0003 mm/year
• Ammonium hydroxide NH₄OH, 10%: 0.0003 mm/year
• Ammonium sulfate (NH₄)₂SO₄, 5%: 0.00 mm/year
• Barium chloride BaCl₂, 10%: 0.0008 mm/year
• Bromine water: 0.19 mm/year
• Calcium chloride CaCl₂, 5%: 0.0003 mm/year
• Chromic acid H₂CrO₄, 5%: 0.041 mm/year
• Citric acid C₆H₈O₇, 10%: 0.00 mm/year
• Copper sulfate CuSO₄, 10%: 0.00 mm/year
• Ferric chloride FeCl₃, 5%: 11 mm/year
• Ferrous ammonium sulfate (NH₄)₂Fe(SO₄)₂·6H₂O, 5%: 0.002 mm/year
• Lactic acid C₃H₆O₃, 10%: 0.001 mm/year
• Methanol CH₃OH: 0.00 mm/year
• Oxalic acid C₂H₂O₄, 5%: 0.003 mm/year
• Oxalic acid C₂H₂O₄, 10%: 0.28 mm/year
• Potassium ferricyanide K₃[Fe(CN)₆] 5%: 0.001 mm/year
• Sodium bisulfite NaHSO₃, 5%: 0.0008 mm/year
• Sodium carbonate Na₂CO₃: 0.00 mm/year
• Sodium chloride NaCl, 10%: 0.0003 mm/year
• Sodium chloride NaCl, 20%: 0.0086 mm/year
• Sodium hypochlorite NaClO, 1%: 0.127 mm/year
• Sodium hypochlorite NaClO, 5%: 0.2 mm/year
• Sodium sulfate Na₂SO₄, 5%: 0.00 mm/year
• Sodium sulfate Na₂SO₄, 10%: 0.0006 mm/year
• Sulfurous acid H₂SO₃5%: 1.09 mm/year
• "
• Tartaric acid HOOC−(CHOH) 2−COOH, 10%: 0.0006 mm/year
• "
• Zinc chloride ZnCl₂, 10%: 0.0003 mm/year

Stress-corrosion cracking - generally very good resistance. The list of known environments that cause SCC in alloy 800:

• 155°C 42% MgCl₂
• 155°C 42% MgCl₂
• Boiling 85% ZnCl₂

Incoloy 800 has very good resistance to SCC in polythionic acid solutions, but wrong heat treatment (holding at 650°C) may lead to sensitisation and low scc resistance. It has also exceptional resistance to SCC in high-temperature water and dilute aqueous solutions. alloy 800 may be better choice for tubing materials in steam generators of pressurized nuclear water reactors.

High-temperature tests - due to iron base, alloy 800 is generally not resistant to temperatures above 670°C, and alloy 800H as well as 800HT are only comparatively better. Nickel-base alloys are much better in this regard.

High-temperature oxidation - medium resistance of alloy 800H and alloy 800HT. Rather poor resistance at temperatures above 925°C, as confirmed by test results:

Average metal affected after 1008h of static oxidation test at indicated temperatures (alloy 800H):

• 980°C: 0.046 mm
• 1095°C: 0.19 mm
• 1150°C: 0.23 mm
• 1205°C: 0.35 mm

Metal loss after 500h of dynamic oxidation test in high-velocity combustion stream at 1090°C equaled 0.77mm (alloy 800H), which is very high.

High-temperature carburization - mediocre resistance, that can be acceptable in some allowances. Nickel based alloys fare noticeably better. Carbon absorption results for alloy 800H in high-temperature tests:

• Ar-5H₂-5CO-5CH₄ 215 h; 870°C: 0.5
• Ar-5H₂-5CO-5CH₄ 215 h; 930°C: 1
• Ar-5H₂-5CO-5CH₄ 55 h; 980°C: 1
• Ar-5H₂-5CO-5CH₄ 24 h; 1090°C: 12.6
• H₂-2CH₄ 100 h (alloy 800); 1000°C: 19

High-temperature nitridation - mediocre resistance. Alloy 800 is not resistant to high temperature nitridation. It corrodes strongly even in pure nitrogen at temperatures above 980°C. Pure nitrogen, however, does not cause problems to alloy 800H and 800 HT. These two alloys, however, are not resistant to high-temperature ammonia. The results of the nitrogen absorption test for the alloy alloy 800H are as follows:

• Ammonia 168 h; 650°C: 4.3
• Ammonia 168 h; 980°C: 4.0
• Ammonia 168 h; 1090°C: 5.5

High-temperature sulfidation - poor resistance. Due to high chromium content and presence of titanium, alloy 800H resists sulfidation for some time, but after few thousand hours rapid breakaway corrosion happens.

High-temperature halogenation - poor resistance, which is evident from the weight-loss experienced after following tests (alloy 800H):

• Ar-30Cl₂ 500 h; 400°C: 6
• Ar-30Cl₂ 500 h; 500°C: 13
• Ar-30Cl₂ 500 h; 705°C: 200-270
• Ar-20O₂-0.25Cl₂ 400 h; 900°C: 26.91
• Ar-20O₂-0.25Cl₂ 400 h; 1000°C: 87.05

Hot corrosion - poor resistance, alloy 800 / 800H / 800HT cannot be used for gas turbines.

Ash/salt deposit corrosion - adequate resistance and alloy 800H is widely used in coal-fired boilers. In a field test when uncooled specimens were exposed in the superheated section at 815°C in a boiler fired with high vanadium Bunker C fuel, measured corrosion rate was 9-12 mm/year.

Weldability

Weldability - alloy 800 belongs to group 45 according to ISO 15608. For brazing, p-number is equal 111, according to ASME, section IX.

Selection of welding consumables for alloy 800:

• Filler metals: ERNiCr-3

Selection of welding consumables for alloy 800H and alloy 800 HT:

• Coated electrodes: ENiCrCoMo-1
• Filler metals: ERNiCr-3 or ERNiCrCoMo-1

Hot-cracking - the alloy is sensitive to hot-cracking due to high iron content. However, one study has found that reducing the aluminum plus titanium content to <0.06% essentially eliminated hot-cracking. It can further mean that alloy 800H and alloy 800HT are more susceptible to hot-cracking due to typically higher Al+Ti content.

Electropolishing

Electropolishing - electrolyte composition: 37 ml of H₃PO₄, 56 ml of glycerol. Platinum cathode. 3.1 A/cm².

Heat treatment and working

Recommended working and heat treatment parameters:

• Hot working: 1205 °C
• Heavy forging: 1010 °C
• Light forging: >870 °C
• First melting temperature: 1260 °C
• Precipitation temperature: 760 °C
• Batch annealing in bell-type furnaces:

Cool rapidly through the range between 760-540°C to ensure freedom from sensitization. Alloy 800 is not susceptible to thermal cracking.

Machining - the alloy 800 / alloy 800H / alloy HT is best machined in the cold-drawn or cold-drawn and stress-relieved conditions.

We deliver this steel alloy as:

• Welding fittings according to ASTM B 366
• Sheets and plates according to ASTM B 409
• Bars according to ASTM B 408
• Seamless pipes according to ASTM B 407. B 829
• Welded pipes according to ASTM B 514. B 775
• Forgings according to AMS 564

Replacements, equivalents and other designations:

1.4558, alloy 800, Ch20n32t, f-3314, FeNi32Cr21AlTi, INCOLOY 800, N08800, NW8800, SANICRO 30, une f-3314, x2nicralti32-20, z10nc32-21, BOHLER H500, EMVAC 800, DMV 4958, DMV 4959, NY800, PYRAD 33, VLX 800, CHRONIMO 1.4876, CRONIDUR 4959, Coralloy 800, HAYNES 800, NY 811, NAS 800, NCF800, SINOXX 4876, UNITEMP 800, AL800, F-3314, Ch20N32T, EP670, ChN32T, NCF800H, NCF800HTB, NCF800HTF, NCF800HTP, NCF800TB