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XM

25/35 Cr/Ni Nb 0.4% C
  • Microalloy Steam Reformer & Cracker

Application

Long-Established 25/35 Alloy

XM is the reference alloy, developed in 1990s for the “heavy-duty” passes of Pyrolysis Cracker Coils where high carburisation resistance is required, and “peak” temperatures can exceed 1125°C, the alloy is widely used today. The very high creep rupture strength also makes it ideal for steam reformer furnaces where high tube temperatures or thinner tube walls are required. Because of the combination of exceptional creep strength and carburisation resistance, microalloyed XM boasts a proven track record of success within the petrochemical industry over many years.

XM is a weldable chromium nickel heat resistant steel which is the microalloyed version of XM. In addition to the controlled niobium content, further creep strengthening is introduced by making microalloy additions. The important elements interact by the process of “synergism” to increase the high temperature strength

Nominal Composition

  • 6
    C Carbon
    0.4
  • 14
    Si Silicon
    1.5
  • 25
    Mn Maganese
    1
  • 24
    Cr Chromium
    25
  • 28
    Ni Nickel
    35
  • 43
    Nb Niobium
    1.2
  • Plus
    Additions

Physical Properties

Thermal Expansion Coefficient (mm/mm°C)Thermal Conductivity (W/m°C)(Density kg/m3)Young Modulus (N/mm2 x 103)Specific Heat (J/KgK)
20 - 100°C - 15.5 x 10⁻⁶100°C - 137.97 x 1020°C - 158.5455
20 - 800°C - 18.9 x 10⁻⁶750°C - 24.3 800°C - 108.2 
20 - 1000°C - 19.4 x 10⁻⁶1000°C - 27.7 1000°C - 95.1 
20 - 1100°C - 19.7 x 10⁻⁶1000°C - 29.7   

Mechanical Properties

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