Method for making a nickel base alloy having improved resistance to hydrogen embittlement

摘要

The present invention relates to a method for making a gamma prime precipitation strengthened nickel base alloy having an improved resistance to hydrogen embrittlement, particularly crack propagation. The alloy is cast, heat treated to dissolve substantially all the gamma-gamma prime eutectic islands and script carbides without causing incipient melting, cooled to below 1000 DEG C., HIP'ed to eliminate porosity, precipitation treated and aged. The alloy has a microstructure which is essentially free of script carbides, gamma-gamma prime eutectic islands and porosity. The microstructure further includes a plurality of regularly occurring large barrier gamma prime precipitates and a continuous field of fine cuboidal gamma prime precipitates surrounding the large barrier gamma prime precipitates.