Alloy 188, 2.4683, UNS R30188, UDIMET Alloy 188, CoCr22Ni22W15 - cobalt alloy

Alloy 188, 2.4683, UNS R30188, UDIMET Alloy 188, CoCr22Ni22W15 - cobalt alloy

Udimet Alloy 188, R30188, 2.4683 – description 

Alloy 188 (UNS R30188) is a cobalt–nickel–chromium–tungsten alloy designed for high-temperature service. It offers excellent strength and stability at elevated temperatures together with outstanding oxidation resistance up to 1095 °C. The alloy also resists sulfidation, hot corrosion from sulfate deposits, and molten chloride salts. A protective and adherent oxide scale, enhanced by its chromium content and lanthanum additions, ensures long-term performance. Alloy 188 is readily fabricated and welded, making it well-suited for demanding gas turbine components such as combustors, liners, flame holders, transition ducts, and cast parts.

Application

Used in military and commercial gas turbine engines for combustion cans, transition ducts and after-burned components.

Physical and Tensile Properties

Room temperature physical properties:

• Density: 8.98 g/cm³
• Melting temperature: 1315-1410 °C

High-Temperature Coefficient of Thermal Expansion, from 20°C to:

• 100°C: 12.1 μm/m⋅K
• 200°C: 12.7 μm/m⋅K
• 300°C: 13.1 μm/m⋅K
• 400°C: 13.5 μm/m⋅K
• 500°C: 13.9 μm/m⋅K
• 600°C: 14.3 μm/m⋅K
• 700°C: 15.0 μm/m⋅K
• 800°C: 15.5 μm/m⋅K
• 900°C: 16.0 μm/m⋅K
• 1000°C: 16.5 μm/m⋅K

Specific Heat Capacity:

• 20°C: 405 J/kg⋅K
• 100°C: 423 J/kg⋅K
• 200°C: 444 J/kg⋅K
• 300°C: 465 J/kg⋅K
• 400°C: 486 J/kg⋅K
• 500°C: 502 J/kg⋅K
• 600°C: 523 J/kg⋅K
• 700°C: 540 J/kg⋅K
• 800°C: 557 J/kg⋅K
• 900°C: 573 J/kg⋅K
• 1000°C: 590 J/kg⋅K

Electrical Resistivity:

• 100°C: 1.03 μΩ·m
• 200°C: 1.05 μΩ·m
• 300°C: 1.07 μΩ·m
• 400°C: 1.10 μΩ·m
• 500°C: 1.13 μΩ·m
• 600°C: 1.15 μΩ·m
• 700°C: 1.16 μΩ·m
• 800°C: 1.18 μΩ·m
• 900°C: 1.18 μΩ·m
• 1000°C: 1.19 μΩ·m

Thermal Conductivity:

• 20°C: 10.4 W/m · K
• 100°C: 12.2 W/m · K
• 200°C: 14.3 W/m · K
• 300°C: 15.9 W/m · K
• 400°C: 17.5 W/m · K
• 500°C: 19.3 W/m · K
• 600°C: 21.1 W/m · K
• 700°C: 23.0 W/m · K
• 800°C: 24.8 W/m · K
• 900°C: 25.5 W/m · K
• 1000°C: 27.6 W/m · K

Poisson's Ratio:

• 20°C: 0.3
• 100°C: 0.29
• 200°C: 0.27
• 300°C: 0.29
• 400°C: 0.29
• 500°C: 0.30
• 600°C: 0.31
• 700°C: 0.32
• 800°C: 0.32
• 900°C: 0.33
• 1000°C: 0.33

Young's Modulus:

• 20°C: 232 GPa
• 100°C: 226 GPa
• 200°C: 220 GPa
• 300°C: 213 GPa
• 400°C: 206 GPa
• 500°C: 198 GPa
• 600°C: 189 GPa
• 700°C: 180 GPa
• 800°C: 171 GPa
• 900°C: 160 GPa
• 1000°C: 150 GPa

Shear Modulus:

• 20°C: 90 GPa
• 100°C: 88 GPa
• 200°C: 86 GPa
• 300°C: 83 GPa
• 400°C: 80 GPa
• 500°C: 76 GPa
• 600°C: 73 GPa
• 700°C: 69 GPa
• 800°C: 65 GPa
• 900°C: 61 GPa
• 1000°C: 56 GPa

Thermal Diffusivity:

• 20°C: 29.2 10^–6⋅m²/s
• 100°C: 32.7 10^–6⋅m²/s
• 200°C: 36.5 10^–6⋅m²/s
• 300°C: 38.7 10^–6⋅m²/s
• 400°C: 40.8 10^–6⋅m²/s
• 500°C: 43.5 10^–6⋅m²/s
• 600°C: 45.7 10^–6⋅m²/s
• 700°C: 48.2 10^–6⋅m²/s
• 800°C: 50.4 10^–6⋅m²/s
• 900°C: 50.4 10^–6⋅m²/s
• 1000°C: 53.0 10^–6⋅m²/s

High-temperature Tensile Properties, Cold-Rolled:

• 20°C:
  • Yield strength 0.2%: 465 MPa
  • Tensile strength: 945 MPa
  • Elongation: 53 %
• 540°C:
  • Yield strength 0.2%: 290 MPa
  • Tensile strength: 750 MPa
  • Elongation: 61 %
• 650°C:
  • Yield strength 0.2%: 275 MPa
  • Tensile strength: 710 MPa
  • Elongation: 59 %
• 760°C:
  • Yield strength 0.2%: 735 MPa
  • Tensile strength: 270 MPa
  • Elongation: 620 %
  • Long-time Strength, 100h: 220 MPa
  • Long-time Strength, 1000h: 160 MPa
• 815°C:
  • Long-time Strength, 100h: 150 MPa
  • Long-time Strength, 1000h: 105 MPa
• 870°C:
  • Yield strength 0.2%: 250 MPa
  • Tensile strength: 415 MPa
  • Elongation: 64 %
  • Long-time Strength, 100h: 99 MPa
  • Long-time Strength, 1000h: 65 MPa
• 925°C:
  • Long-time Strength, 100h: 63 MPa
  • Long-time Strength, 1000h: 38 MPa
• 980°C:
  • Yield strength 0.2%: 130 MPa
  • Tensile strength: 245 MPa
  • Elongation: 59 %
  • Long-time Strength, 100h: 37 MPa
  • Long-time Strength, 1000h: 17 MPa
• 1095°C:
  • Yield strength 0.2%: 64 MPa
  • Tensile strength: 130 MPa
  • Elongation: 32 %

High-temperature Tensile Properties, Hot-Rolled Sheet and Plates:

• 20°C:
  • Yield strength 0.2%: 470 MPa
  • Tensile strength: 985 MPa
  • Elongation: 56 %
• 540°C:
  • Yield strength 0.2%: 275 MPa
  • Tensile strength: 775 MPa
  • Elongation: 69 %
• 650°C:
  • Yield strength 0.2%: 265 MPa
  • Tensile strength: 755 MPa
  • Elongation: 73 %
• 760°C:
  • Yield strength 0.2%: 270 MPa
  • Tensile strength: 650 MPa
  • Elongation: 70 %
  • Long-time Strength, 100h: 255 MPa
  • Long-time Strength, 1000h: 179 MPa
  • Long-time Strength, 10 000h: 128 MPa
• 815°C:
  • Long-time Strength, 100h: 172 MPa
  • Long-time Strength, 1000h: 121 MPa
  • Long-time Strength, 10 000h: 83 MPa
• 870°C:
  • Yield strength 0.2%: 250 MPa
  • Tensile strength: 450 MPa
  • Elongation: 77 %
  • Long-time Strength, 100h: 117 MPa
  • Long-time Strength, 1000h: 80 MPa
  • Long-time Strength, 10 000h: 54 MPa
• 925°C:
  • Long-time Strength, 100h: 77 MPa
  • Long-time Strength, 1000h: 50 MPa
• 980°C:
  • Yield strength 0.2%: 185 MPa
  • Tensile strength: 265 MPa
  • Elongation: 84 %
  • Long-time Strength, 100h: 48 MPa
  • Long-time Strength, 1000h: 30 MPa
• 1095°C:
  • Yield strength 0.2%: 88 MPa
  • Tensile strength: 145 MPa
  • Elongation: 89 %
• 1150°C:
  • Yield strength 0.2%: 48 MPa
  • Tensile strength: 96 MPa
  • Elongation: 60 %
• 1200°C:
  • Yield strength 0.2%: 28 MPa
  • Tensile strength: 83 MPa
  • Elongation: 71 %

0,5% Creep Strength of Cold-Rolled and Solution-Annealed Sheet:

• 760°C, 10h: 155 MPa
• 760°C, 100h: 115 MPa
• 760°C, 1000h: 81 MPa
• 815°C, 10h: 105 MPa
• 815°C, 100h: 77 MPa
• 815°C, 1000h: 54 MPa
• 870°C, 10h: 74 MPa
• 870°C, 100h: 52 MPa
• 870°C, 1000h: 34 MPa
• 925°C, 10h: 50 MPa
• 925°C, 100h: 34 MPa
• 925°C, 1000h: 21 MPa
• 980°C, 10h: 34 MPa
• 980°C, 100h: 21 MPa
• 980°C, 1000h: 12 MPa

1,0% Creep Strength of Cold-Rolled and Solution-Annealed Sheet:

• 760°C, 10h: 175 MPa
• 760°C, 100h: 130 MPa
• 760°C, 1000h: 92 MPa
• 815°C, 10h: 120 MPa
• 815°C, 100h: 87 MPa
• 815°C, 1000h: 61 MPa
• 870°C, 10h: 84 MPa
• 870°C, 100h: 58 MPa
• 870°C, 1000h: 39 MPa
• 925°C, 10h: 57 MPa
• 925°C, 100h: 39 MPa
• 925°C, 1000h: 25 MPa
• 980°C, 10h: 39 MPa
• 980°C, 100h: 25 MPa
• 980°C, 1000h: 14 MPa

Corrosion Resistance

Alloy 188 is not specifically engineered for use in corrosive aqueous environments. Nevertheless, it offers outstanding high-temperature strength together with very good resistance to oxidizing conditions at temperatures up to 1095 °C during extended exposure. The alloy also demonstrates excellent resistance to sulfate-deposit hot corrosion, is highly resistant to molten chloride salts, and provides good protection against gaseous sulfidation.

High-temperature oxidation - very good resistance. 1008h long flowing air oxidation test results:

• 980°C:
  • Metal loss: 3 μm
  • Average metal affected: 28 μm
• 1090°C:
  • Metal loss: 13 μm
  • Average metal affected: 94 μm
• 1150°C:
  • Metal loss: 218 μm
  • Average metal affected: 272 μm

– very good resistance. After 1000 hours of testing the alloy in aviation fuel containing 0.4% sulfur, with a fuel-to-air ratio of 1 to 30, the average metal penetration was 69 micrometers, and the total metal loss was 20 micrometers.

Heat Treatment, Working and Machining

HAYNES® 188 alloy is easy to fabricate thanks to its good ductility. It can be hot-worked after being heated to 1175°C long enough for the entire piece to reach temperature, and it can also be shaped by cold working. Because the alloy hardens quickly during cold working, intermediate annealing may be necessary for forming complex parts. After any hot- or cold-working, components should be annealed and rapidly cooled to restore their full set of properties.

Standard recommended working and heat treatment parameters:

• Hot forming: 1175°C
• Intermediate annealing: 1175°C
• Solution-treatment: 1163-1191°C

We deliver this steel alloy as:

• Bars, rings, forgings according to AMS 5772
• Plates, strips and sheets according to AMS 5608
• Filler metal according to AMS 5801