For best performance of low-expansion properties, up to 300°C, look no further than Alloy 42

Alloy 42 has been specifically manufactured for composite tooling and exhibits a low thermal expansion from cryogenic temperatures up to 300°C.

  • UNS Number: K94100
  • Werkstoff Number: 1.3917
  • ASTM: F30, B753.
  • Other: DIN 17744, AFNOR NF A54-301

Product availability

Round Bar
Welding Wire

Chemical analysis



  • Cryogenic components
  • Glass to metal and ceramic to metal seals
  • Semiconductor packages
  • Tooling and dies for composite forming
  • Electronic tubes
  • CRT electron guns
  • Microelectronic components
  • Thermostat rods
  • Vacuum devices
  • Electric industrial lamps
  • Bi-metal temperature switches
  • Liquid Gas Storage tanks

About Alloy 42

NeoNickel supplies Alloy 42 in accordance to the ASTM-F-1684 specification and is manufactured for industrial applications where a low Coefficient of Thermal Expansion (CTE) is required over a range of temperatures. The constraints of the specifications limit the Sulphur and Phosphorus content of the material for increased weldability.

Features of Alloy 42 include:

  • Low Expansion Rate up to 300°C
  • Readily Weldable
  • Easily Machined
  • Ideal for Composite Tooling
  • Density: 8.12 g/cm³
  • Melting Range: 1425°C - 1435°C
  • Curie Temperature: 380°C
  • Thermal Conductivity at 20/100°C: 10.7 W/m-K
  • Modulus of Elasticity at 20°C: 148 GPa
  • Coefficient of Thermal Expansion: -
  • 30 – 300°C: 4.0 – 4.7 (10-6/°C)
  • 30 – 450°C: 6.7 – 7.4 (10-6/°C)
Proud members of the British Valve & Actuator AssociationProud members of the British Valve & Actuator Association