Multimet N155 is a nickel-cobalt-chromium superalloy strengthened with molybdenum, tungsten, and nitrogen. It is designed for high-temperature service requiring both mechanical strength and oxidation resistance. Unlike precipitation-hardening alloys, N155 derives its properties from solid-solution strengthening, allowing use in the solution-treated condition without complex aging cycles.

1. Operating Limits & Selection Criteria

This alloy is selected for intermediate high-temperature service where both creep strength and environmental resistance are required.

• Effective Temperature Range: Retains useful mechanical strength up to 732°C (1350°F) . Short-term exposure possible at higher temperatures, but oxidation and strength loss accelerate above this range.

• Oxidation Resistance: Chromium and cobalt content provide good resistance to scaling and combustion products up to 980°C (1800°F) for intermittent service.

• Comparison to Other Superalloys: Offers better fabricability than many nickel-based superalloys, with strength levels between A-286 and more highly alloyed grades like Waspaloy. Suitable when formability plus high-temperature strength is required.

• Thermal Stability: Long-term exposure at upper temperature limits may result in sigma phase formation, which reduces ductility. Verify compatibility for extended service above 650°C.

2. Manufacturing Data & Specifications

• Chemical Composition (Specification Ranges)

  Element	Weight %
  Carbon (C)	0.08 - 0.16
  Manganese (Mn)	1.00 - 2.00
  Silicon (Si)	1.00 max
  Phosphorus (P)	0.040 max
  Sulfur (S)	0.030 max
  Chromium (Cr)	20.00 - 22.50
  Nickel (Ni)	19.00 - 21.00
  Cobalt (Co)	18.50 - 21.00
  Molybdenum (Mo)	2.50 - 3.50
  Tungsten (W)	2.00 - 3.00
  Niobium (Nb)	0.75 - 1.25
  Nitrogen (N)	0.10 - 0.20
  Iron (Fe)	Balance

• Physical Properties (Typical)

  Property	Metric	Imperial
  Density	8.19 g/cm³	0.296 lb/in³
  Melting Range	1315-1370°C	2400-2500°F

• Mechanical Properties (Solution Treated)

  Form / Specification	Tensile Strength	Yield Strength (0.2%)	Elongation	Hardness
  Sheet/Plate (AMS 5532)	760-965 MPa (110-140 ksi)	380 MPa min (55 ksi)	40% min	-
  Bar (AMS 5769)	860 MPa min (125 ksi)	410 MPa min (60 ksi)	30% min	156-217 HB
  Values are typical minimums; actual properties vary by section size and heat treatment.

• Fabrication Considerations

  • Heat Treatment: Supplied in solution-treated condition (1177°C / 2150°F, water quench). No further aging required. Do not anneal below solution temperature if high-temperature strength is required.

  • Forming: Good ductility allows conventional forming operations. Higher springback than stainless steel due to strength.

  • Welding: Readily welded by gas tungsten arc (GTAW) and gas metal arc (GMAW) processes using matching filler (AMS 5794). Post-weld heat treatment not required for service within design limits.

3. Applications

Multimet N155 is specified for gas turbine and airframe components operating in the 540-730°C range:

• Aircraft exhaust systems: Tailpipes, tail cones, exhaust manifolds

• Turbine engine components: Afterburner liners, combustion chambers, transition ducts

• Rotating hardware: Turbine blades, vanes, shafts, rotors (where alloy selection permits)

• Fasteners: High-temperature bolts for turbine casings

• Land-based gas turbine components requiring oxidation resistance

4. Available Product Forms & Supply

For engineers and procurement specialists requiring high-temperature alloys for turbine and aerospace applications, ZYTC Alloy stocks certified Multimet N155 (UNS R30155) to AMS specifications:

• Bar & Rod (AMS 5769)

• Sheet & Plate (AMS 5532)

• Welding Wire (AMS 5794)

• Coated Electrodes (AMS 5795)

All material is supplied with full traceability and certification, suitable for mission-critical aerospace and power generation applications. Contact ZYTC Alloy for stock availability and pricing.

Email: daisy@zytcsteel.com

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