STP425: Stress Corrosion Cracking Rates of a Nickel-Brass Alloy Under Applied Potential

    McKinney, Nancy
    Chemist and chemist, Bell Telephone Laboratories, Inc., Holmdel, N. J.

    Hermance, H. W.
    Chemist and chemist, Bell Telephone Laboratories, Inc., Holmdel, N. J.

    Pages: 18    Published: Jan 1967


    A method was developed to test the susceptibility of nickelbrass alloys to stress corrosion cracking in the presence of nitrates or other salts. A wire of the alloy under test was stressed, and an electrical leakage path was provided to a cathode by a filter paper impregnated with the electrolyte being studied. Stresses, potentials, salt concentrations, relative humidities, and time were varied to evaluate these factors. In the case of ASTM Grade D nickel-brass alloy, using ammonium nitrate as the electrolyte, the rate of crack penetration increased with increases in the salt concentration in the leakage path, the applied stress, relative humidity, and temperature. There was no direct correlation with the applied potential. Other hygroscopic nitrates such as zinc, and to a lesser degree calcium and copper, also caused stress corrosion cracking. Chlorides and sulfates were ineffective under conditions in which nitrates produced cracking. From the data obtained, the expected failure times of nickel-brass parts at average ambient temperature and humidity could be estimated.


    copper alloys, nickel alloys, zinc alloys, corrosion, stress corrosion, electric potential, nitrates, humidity, sulfates, chlorides, salt water

    Paper ID: STP46465S

    Committee/Subcommittee: G01.05

    DOI: 10.1520/STP46465S

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