Nickel base superalloy single crystal articles with improved performance in air and hydrogen

• Main Authors: DeLuca, Daniel P, Cowles, Bradford A, Gell, Maurice L, Duhl, David N, Cetel, Alan D, Biondo, Charles M
• Format: Patent
• Language: English
• Published: 12.03.2002

This invention relates to nickel base superalloy articles possessing improved resistance to hydrogen embrittlement, and also improved fatigue resistance in air. The invention comprises a combination of aspects including composition, and heat treatment which produce an unexpected improvement in properties in certain environments. The invention primarily comprises a limited composition range in combination with a specific heat treatment and a HIP treatment. The result of this product has the unique combination of properties previously described. Compositional requirements and processing improvements are disclosed which improve the hydrogen embrittlement resistance and the fatigue resistance in air of nickel base single crystal articles. The compositional requirements enlarge the difference between the ′ solvus temperature and the incipient melting temperature, thus enabling the solution of / ′ eutectic islands without causing incipient melting, while hot isostatic pressing and careful melt practice eliminate porosity and carbides, borides and nitrides, all of which act as crack initiation sites.