Low Expansion 43-PH

Low Expansion 43-PH is an age-hardenable, ferromagnetic, austenitic alloy with a constant modulus of elasticity, inherent high-strength, good formability, adjustable elastic coefficient, and low mechanical hysteresis. Due to its insensitivity to temperature changes, the temperature compensation of Low Expansion 43-PH is extremely reliable, and, in some cases, mechanical linkage corrections may be unnecessary. The thermal elastic coefficient (TEC) of this alloy can be adjusted to zero, or some value near zero, by varying the aging temperature and the degree of prior cold work applied to the material. Low Expansion 43-PH is considered in precision devices where a stressed member must maintain a constant stiffness or deflection, deliver a constant force, or where a vibrating member must maintain a constant frequency regardless of the ambient temperature in the range of -50°F to 150°F (-47°C to 66°C).

Type Analysis

  • Carbon (Maximum) 0.03
  • Silicon (Maximum) 0.5
  • Nickel (Nominal) 42.5
  • Titanium (Nominal) 2.5
  • Manganese (Maximum) 0.5
  • Chromium (Nominal) 5.25
  • Iron (Nominal) Balance
  • Aluminum (Nominal) 0.5


Springs, diaphragms and supports in timing and measuring devices, continuous weighing systems, flow meters, gyro suspensions, motor speed switches, bourdon tubes and tuning forks

Applicable Specifications

  • AMS 5221C
  • AMS 5223C
  • AMS 5225C





Technical Information


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