Monel K500, Alloy K500, 2.4375, UNS N05500 - nickel alloy

Alloy K500, 2.4375, UNS N05500, Monel® alloy K-500 - nickel alloy according to AMS 4676, NACE MR 0175 / ISO 15156, API 6ACRA

Alloy K500, 2.4375, UNS N05500, Monel® alloy K-500 – description

Alloy K500 (Monel® K500, UNS N05500) is a Ni-Cu based alloy with alloying of titanium and aluminium, age-hardenable, and extremely corrosion resistant in the marine environment, chemical processing and oil well environment. It is NACE MR 0175 / ISO 15156 and API 6ACRA certified. It can be seen as a stronger and harder variation of Monel® alloy 400. It has a high tensile strength up to 650°C in the aged condition. It is available in cold or hot-formed condition or with subsequent heat treatment in solution-annealed or age-hardened condition.

Monel® K-500 is virtually non-magnetic, which is important in some applications, like oil-surveying equipment and electronic components. However, during processing a magnetic surface layer may be developed, particularly on thin wire or strip. Pickling or bright dipping in acid removes the magnetic film. The alloy is suitable for many cryogenic applications, as no ductile-to-brittle transformation occurs at temperatures as low as that of liquid hydrogen. Monel® alloy K-500 is approved by the ASME Boiler and Pressure Vessel Code as an acceptable material for use as bolting up to 235°C.

Applications

Used in offshore engineering (valve seals, wearing rings), shipbuilding (fasteners, mounting elements), oil drill wells and oil processing (pump shafts, pump impellers, oil well collars, springs, valve trims), chemical processing (pump and valve components), paper industry (doctor blades, scrapers), and aircraft instrument components.

Physical and Tensile Properties

Room temperature physical properties:

• Density: 8.44 g/cm³
• Melting Temperature: 1315-1350 °C
• Magnetic Permeability: 1.0006
• Curie Temperature: -100°C (age hardened)
• Curie Temperature: -135°C (annealed)

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

• -130°C: 12.3 μm/m⋅K
• 100°C: 13.7 μm/m⋅K
• 200°C: 14.6 μm/m⋅K
• 300°C: 14.9 μm/m⋅K
• 400°C: 15.2 μm/m⋅K
• 500°C: 15.5 μm/m⋅K
• 600°C: 16 μm/m⋅K
• 700°C: 16.6 μm/m⋅K
• 800°C: 17 μm/m⋅K
• 900°C: 17.5 μm/m⋅K

Thermal Conductivity:

• -130°C: 13.3 W/m · K
• 20°C: 17.4 W/m · K
• 100°C: 19.4 W/m · K
• 200°C: 20.9 W/m · K
• 300°C: 25.1 W/m · K
• 400°C: 27.8 W/m · K
• 500°C: 30.5 W/m · K
• 600°C: 33.1 W/m · K
• 700°C: 35.7 W/m · K
• 800°C: 37.4 W/m · K
• 900°C: 41.2 W/m · K

Specific Heat Capacity:

• -130°C: 323 J/kg⋅K
• 20°C: 420 J/kg⋅K
• 100°C: 545 J/kg⋅K
• 200°C: 480 J/kg⋅K
• 300°C: 491 J/kg⋅K
• 400°C: 500 J/kg⋅K
• 500°C: 517 J/kg⋅K
• 600°C: 538 J/kg⋅K
• 700°C: 567 J/kg⋅K
• 800°C: 613 J/kg⋅K
• 900°C: 685 J/kg⋅K

Electrical Resistivity:

• 20°C: 6.1 μΩ·m
• 100°C: 6.2 μΩ·m
• 200°C: 6.3 μΩ·m
• 300°C: 6.5 μΩ·m
• 400°C: 6.5 μΩ·m
• 500°C: 6.5 μΩ·m
• 600°C: 6.6 μΩ·m
• 700°C: 6.6 μΩ·m
• 800°C: 6.7 μΩ·m
• 900°C: 6.8 μΩ·m

Young's Modulus:

• 20°C: 179 GPa
• 100°C: 178 GPa
• 200°C: 176 GPa
• 300°C: 173 GPa
• 400°C: 168 GPa
• 500°C: 164 GPa
• 600°C: 162 GPa
• 700°C: 158 GPa

High-Temperature Mechanical Properties of Alloy K500 in solutioned and aged condition:

• 20°C:
  • Yield strength: 690 MPa
  • Tensile strength: 1100 MPa
  • Elongation: 24 %
• 100°C:
  • Yield strength: 670 MPa
  • Tensile strength: 1040 MPa
• 200°C:
  • Yield strength: 640 MPa
  • Tensile strength: 1020 MPa
• 300°C:
  • Yield strength: 620 MPa
  • Tensile strength: 980 MPa
• 400°C:
  • Yield strength: 600 MPa
  • Tensile strength: 890 MPa
• 500°C:
  • Yield strength: 570 MPa
  • Tensile strength: 750 MPa
• 600°C:
  • Yield strength: 490 MPa
  • Tensile strength: 620 MPa

Nominal Mechanical Properties of Monel® K-500 cold-drawn rods and bars:

• Annealed:
  • Yield strength: 276-414 MPa
  • Tensile strength: 621-758 MPa
  • Elongation: 50-25 %
• Annealed and aged:
  • Yield strength: 586-827 MPa
  • Tensile strength: 896-1310 MPa
  • Elongation: 30-20 %

Nominal Mechanical Properties of Monel® K-500 cold-drawn rods and bars:

• Annealed:
  • Yield strength: 276-414 MPa
  • Tensile strength: 621-758 MPa
  • Elongation: 50-25 %
• Annealed and aged:
  • Yield strength: 586-827 MPa
  • Tensile strength: 896-1310 MPa
  • Elongation: 30-20 %

Nominal Mechanical Properties of Monel® K-500 cold-drawn strips:

• Spring Tempered:
  • Yield strength: 896-1103 MPa
  • Tensile strength: 1000-1138 MPa
  • Elongation: 8-3 %
  • Hardness: >25 HC %
• Spring Tempered and Aged:
  • Yield strength: 896-1345 MPa
  • Tensile strength: 1172-1517 MPa
  • Elongation: 10-5 %
  • Hardness: > 34 HC %

Nominal Mechanical Properties of Monel® K-500 cold-drawn tubes and pipes:

• Annealed:
  • Yield strength: 276-448 MPa
  • Tensile strength: 621-758 MPa
  • Elongation: 45-25 %
• Annealed and aged:
  • Yield strength: 586-827 MPa
  • Tensile strength: 896-1241 MPa
  • Elongation: 30-15 %

Nominal Mechanical Properties of Monel® K-500 cold-drawn wires:

• Annealed:
  • Yield strength: 241-448 MPa
  • Tensile strength: 552-758 MPa
  • Elongation: 40-20 %
• Annealed and aged:
  • Yield strength: 621-758 MPa
  • Tensile strength: 827-1034 MPa
  • Elongation: 30-15 %
• Spring Tempered and Aged:
  • Yield strength: 965-1310 MPa
  • Tensile strength: 1103-1379 MPa
  • Elongation: 8-3 %

Nominal Mechanical Properties of Monel® K-500 cold-rolled sheet:

• Yield strength: 276-448 MPa
• Tensile strength: 621-724 MPa
• Elongation: 45-25 %

High-Temperature Hardness of alloy K500 hot-finished and aged:

• 20°C: 331 HBW
• 370°C: 311 HBW
• 425°C: 302 HBW
• 480°C: 293 HBW
• 540°C: 255 HBW
• 595°C: 229 HBW

Corrosion Resistance

Monel® K-500, a nickel-copper alloy, is more resistant to reducing environment than nickel and more resistant to oxidizing environment than copper. It is generally free from stress-corrosion cracking.

Seawater - exceptional resistance. In stagnant water fouling may occur followed by pitting, but the process slows down after a fairly rapid initial attack. After 3 years of testing in stagnant seawater, maximum pit depth was 0.864 mm.

Oil well environment - very good resistance. NACE MR0175 / ISO 15156 states that the alloy can be used in ""without restriction on temperature, pH2S, Cl−, or in situ pH in production environments"".

Weldability

Good weldability. Best results are achieved with GTAW process. The material should be in the solution-annealed condition. Post-welding heat treatment of 850-900°C with rapid cooling is recommended. After the treatment, the component may be age-hardened, but the weldment itself would not achieve the strength of the base metal.

Filler metal - VDM FM 60 (2.4377), Monel® filler metal 60, S Ni 4060, UNS N04060, ERNiCu-7.

Heat Treatment, Working and Machining

Hot forming temperature range is 880-1150°C (1040 is the minimum temperature for heavy forging). Withdraw the piece when heated, as prolonged soaking at this temperature is harmful. For best results, the last forging operation should include reheating to 1090°C and at least 30% reduction of area. Water quench is the recommended method of cooling.

Cold forming should be carried in the annealed condition. It requires significant force but yields good results due to the alloy's excellent ductility.

Solution annealing of hot-finished products is performed at 980°C, and of cold-worked ones at 1040°C. To avoid excessive grain growth, time at temperature should be kept to below 30 minutes. Both heating and cooling should be performed as fast as possible.

Intermediate annealing may be required to soften the product during the production of forming. It is usually performed at temperatures between 760 and 870°C for 1h.

Age hardening procedure of:

• Soft material (140-180 HBW) - as-forged and quenched or annealed forgings, annealed or hot-rolled rods, large cold-drawn rods, and soft-temper wire and strip:
  • Age hardening: 580-610°C; 16h
  • Furnace cooling: 12°C / h down to 480°C
  • Air cooling:
• Moderately cold-worked material - cold-drawn rods, half-hard strip, cold-upset pieces and intermediate-temper wire:
  • Age hardening: 580-610°C; 8h
  • Furnace cooling: 12°C / h down to 480°C
  • Air cooling:
• Fully cold-worked material (260-325 HBW, 25-35 HC) - spring-temper strip, spring wire or heavily cold-worked pieces such as small, cold-formed balls:
  • Age hardening: 520-540°C; 6h
  • Furnace cooling: 12°C / h down to 480°C
  • Air cooling:

The machinability is difficult. Roughing should be performed in the annealed condition, and finishing the aged condition.

Turning parameters of Monel® K-500 alloy with a turning tool made out of coated carbide:

• Roughing in the annealed condition:
  • Feed: 0.25 mm/rev
  • Cutting speed: 244 m/min
  • Depth of cut: 6.35 mm
• Finishing in the hardened condition:
  • Feed: 0.13 mm/rev
  • Cutting speed: 35 m/min
  • Depth of cut: 1.02 mm

We deliver this steel alloy as:

• Rod, bar, wire, forging according to DIN 17743, 17752, 17754
• Rod, bar, wire, forging according to ASTM B 865 / ASME SB-865
• Rod, bar, wire, forging according to NACE MR 0103, MR0175 / ISO 15156
• Rod, bar, wire, forging according to AMS 4676
• Rod, bar, wire, forging according to QQ-N-286 Form 1,2

Replacements, equivalents and other designations:

Monel® K-500, Monel® alloy K-500, Monel® K500, N05500, ASTM B 865 (N05500) / ASME SB-865 (N05500), AMS 4676, MIL N-24549, Nickelvac K-500, VDM alloy K-500, CarTech K500 Alloy, MIL-V-17547, QQ N-286, DMV 500, Ni-Cu K500, SPEC MIL-N-24549, Coralloy K-500, 2.4375, NiCu30Al, H05500, NS6500, NA 18 BS 3072, NA 18 BS 3073, NA 18 BS 3074, NA 18 BS 3075, NA 18 BS 3076, NW5500, K-Monel® TU 14-1-3917-85, N65D29JuT-ISh, Nicorros Al