Technical Resources

Hastelloy 22, Alloy C2000®, Alloy 59, Hastelloy C276 and Inconel Alloy 686


Hastelloy® C2000, Alloy C276, Alloy 686, Hastelloy 22 and Alloy 59 are all nickel based alloys. Incredibly corrosion resistant, Hastelloy Alloy and its related alloys offer excellent quality in a range of applications.

The key alloying elements of these metals are Molybdenum, tungsten and Chromium, each with their own unique qualities:


  • Chromium enhances corrosion resistance in oxidizing environments.
  • Molybdenum enhances corrosion resistance in reducing environments.
  • Tungsten, Chromium and molybdenum improve the crevice corrosion and pitting resistance characteristics of the alloy.

CHEMICAL ANALYSIS

The chemical anlaysis of these alloys is as follows:

Alloy (UNS) Mo Cr W Ni Fe Cu Carbon
C2000 (N06200) 15.00-17.00 22.00-24.00 - Bal 3.00 max. 1.30-1.90 0.010max.
22 (N06022) 12.50-14.50 20.00-22.50 2.50-3.50 Bal 2.00-6.00 - 0.015max.
686 (N06686) 15.00-17.00 19.00-23.00 3.00-4.40 Bal 1.00 max. - 0.010max.
59 (N06059) 15.00-16.50 22.00-24.00 Bal 1.00 nom. - 0.010max.
C276 (N10276) 15.00-17.00 14.50-16.50 3.00-4.50 Bal 4.00-7.00 - 0.010max.

ESSENTIAL INFORMATION

With the advent of AOD/VOD refining, the Carbon and Silicon contents of the entire “C” family of alloys are controlled to very low limits, reducing the effect of continuous grain boundary precipitates in the HAZ (Heat Affected Zone).

  • The specified Carbon content across the alloys is 0.015% maximum, with Silicon content of 0.10% maximum.
  • All alloys are produced with the Carbon content below 0.005 % maximum, and Silicon content 0.050 % maximum.

  • PITTING RESISTANCE EQUIVALENT

    Critical pitting resistance and crevice corrosion properties can be measured using the “pitting resistance equivalent” (PREN or PRE) index.

    • PREN = %Cr + 1.5(%MO + %W + %Nb)
    • PRE = %Cr + 3.3(%Mo) + 30N

    Alloy PRE INDEX PREN INDEX
    59 76 47
    22 65 46
    C2000 76 47
    686 74 51
    C276 59 45

    • Localised corrosion resistance in the Green Death Solutions (11.4%H2S04 + 1.2%HCL + 1%FeCl3 +1%CuCl2). Above 120°C the Green Death Solution chemically breaks down.
    Alloy CPT(°C) CCT(°C)
    59 >120 110
    C2000 110 100
    C276 110 105
    22 120 105
    686 >20 110

    • Localised Corrosion Resistance in 10% FeCL3 Solution (ASTM G 48). Above 85 °C, the 10% FeCL3 solution breaks down.
    Alloy CPT(°C) CCT(°C)
    686 >85 >85
    C276 >85 >85
    C2000® >85 >85
    59 >85 >85
    C22 >85 58

    • Thermal Stability properties can be measured by completing the ASTM G28A & G28B tests after sensitising the material at 871°C. Corrosion rate (mpy).
    Media C276 22 686 C2000 59
    ASTM G28A >500 >500 872 116 40
    ASTMG28B >500 339 17 >500 4
    Pitting attack severe severe severe severe none
    Intergranular attack severe severe severe severe none

    • Alloy C276, 22, C2000® and 686: Heavy pitting attack due to intergranular attack.
    • Alloy 59: No attack.