Hastelloy N®, UNS N10003, NiMo17Cr17 - molten salt resistant nickel alloy

Hastelloy N, UNS N10003, NiMo17Cr17 - molten salt resistant nickel alloy according to ASTM B573/B434

Hastelloy N, N10003 – description

Hastelloy N (UNS N10003) is Ni-Mo-Cr corrosion-resistant with excellent resistance to hot fluoride salts in the temperature range of 705-870°C. It has also good resistance to aging and embrittlement and good fabricability.

Hastelloy N was invented at Oak Ridge Laboratories specifically to contain fuel for Molten Salt Reactors. It designed for 30 years life cycle and was actually put to use in years 1964-1969 when the first prototype of Molten Salt Reactor was in operation. Hastelloy N is to this day the best performing alloy in this environment, and with the MSR technology is trending again, the alloy is gaining popularity too. You can read more in this article.

Applications

Developed specificaly for primary-loop service in molten salt reactors. May be used also in environments with molten halides of zirconium, beryllium, lithium, sodium, potassium, thorium or uranium.

Physical and Tensile Properties

Room temperature physical properties:

• Density: 8.86 g/cm³
• Liquidus Temperature: 1300 °C
• Solidus Temperature: 1400 °C

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

• 200°C: 12.3 μm/m⋅K
• 400°C: 13.0 μm/m⋅K
• 600°C: 13.4 μm/m⋅K
• 700°C: 13.8 μm/m⋅K
• 800°C: 14.5 μm/m⋅K
• 900°C: 14.9 μm/m⋅K

Thermal Conductivity:

• 200°C: 13.1 W/m · K
• 300°C: 14.4 W/m · K
• 400°C: 16.5 W/m · K
• 500°C: 18.0 W/m · K
• 600°C: 20.3 W/m · K
• 700°C: 23.6 W/m · K

Electrical Resistivity:

• 20°C: 1.205 μΩ·m
• 705°C: 1.26 μΩ·m
• 815°C: 1.241 μΩ·m

Young's Modulus:

• 20°C: 219 GPa
• 200°C: 204 GPa
• 400°C: 192 GPa
• 600°C: 181 GPa
• 700°C: 171 GPa
• 800°C: 163 GPa
• 900°C: 151 GPa
• 1000°C: 136 GPa

Specific Heat Capacity:

• 100°C: 219 J/kg⋅K
• 200°C: 204 J/kg⋅K
• 300°C: 192 J/kg⋅K
• 400°C: 181 J/kg⋅K
• 480°C: 171 J/kg⋅K
• 540°C: 163 J/kg⋅K
• 570°C: 151 J/kg⋅K
• 590°C: 136 J/kg⋅K
• 620°C: 181 J/kg⋅K
• 660°C: 171 J/kg⋅K
• 680°C: 163 J/kg⋅K
• 700°C: 151 J/kg⋅K

Thermal Stability - room temperature hardness after aging in high temperature:

• as annealed: 96 HRB
• 815°C, 4h: 92 HRB
• 815°C, 8h: 97 HRB
• 815°C, 16h: 96 HRB
• 815°C, 32h: 97 HRB
• 815°C, 64h: 99 HRB
• 815°C, 128h: 96 HRB

Tensile Properties when heat-treated (1177°C):

• 20°C:
  • Yield strength: 314 MPa
  • Tensile strength: 794 MPa
  • Elongation: 50.7 %
• 600°C:
  • Yield strength: 227 MPa
  • Tensile strength: 599 MPa
  • Elongation: 45.3 %
• 700°C:
  • Yield strength: 218 MPa
  • Tensile strength: 480 MPa
  • Elongation: 30 %
• 815°C:
  • Yield strength: 203 MPa
  • Tensile strength: 385 MPa
  • Elongation: 24.3 %
• 925°C:
  • Yield strength: 179 MPa
  • Tensile strength: 234 MPa
  • Elongation: 30 %

Tensile Properties when aged (128h, 815°C):

• Yield strength: 340 MPa
• Tensile strength: 796 MPa
• Elongation: 46.8 %

Tensile Properties when heat-treated and welded:

• 20°C:
  • Tensile strength: 800 MPa
  • Elongation: 37.5 %
• 650°C:
  • Tensile strength: 493 MPa
  • Elongation: 17 %
• 700°C:
  • Tensile strength: 438 MPa
  • Elongation: 10.5 %
• 815°C:
  • Tensile strength: 359 MPa
  • Elongation: 8.5 %

Average Stress-Rupture Data:

• 590°C, 552 MPa
  • Life: 0.4 h
  • Elongation: 44 %
  • Reduction of Area: 31.6 %
• 590°C, 414 MPa
  • Life: 38.9 h
  • Elongation: 21 %
  • Reduction of Area: 19.4 %
• 590°C, 379 MPa
  • Life: 87.7 h
  • Elongation: 17.4 %
  • Reduction of Area: 16.9 %
• 705°C, 241 MPa
  • Life: 18.6 h
  • Elongation: 11.8 %
  • Reduction of Area: 11.0 %
• 705°C, 172 MPa
  • Life: 129.6 h
  • Elongation: 26.5 %
  • Reduction of Area: 10.3 %
• 705°C, 138 MPa
  • Life: 338.6 h
  • Elongation: 12.6 %
  • Reduction of Area: 9.0 %
• 815°C, 103 MPa
  • Life: 19.0 h
  • Elongation: 15.4 %
  • Reduction of Area: 9.6 %
• 815°C, 69 MPa
  • Life: 78.6 h
  • Elongation: 13.8 %
  • Reduction of Area: 9.5 %
• 815°C, 55 MPa
  • Life: 172.2 h
  • Elongation: 18.4 %
  • Reduction of Area: 10.1 %
• 925°C, 41 MPa
  • Life: 24.3 h
  • Elongation: 21.0 %
  • Reduction of Area: 21.4 %
• 925°C, 28 MPa
  • Life: 75.5 h
  • Elongation: 19.3 %
  • Reduction of Area: 11.5 %
• 925°C, 21 MPa
  • Life: 219.6 h
  • Elongation: 28.0 %
  • Reduction of Area: 11.5 %

Corrosion Resistance

Good oxidation and carburization resistance, as well as aging and embrittlement resistance. Exceptional resistance to hot fluoride salts, with continous operation in such environment possible up to as much as 980°C. In molten salt reactor's fuel salt (LiF-BeF₂) at 700°C the corrosion rate is less than 0,025 mm/year. In MSR coolant salt (NaBF₄-NaF) at 607°C the corrosion rate is about 0,015 mm/year.

Heat Treatment, Working and Machining

Standard recommended working and heat treatment parameters:

• Hot forming: 1177-870°C
• Solution-treatment: 1160-1190°C, 8 min°C

Good weldability by manual and automatic means. Use ERNiMo-2 welding wire.