Method of making superalloy turbine disks having graded coarse and fine grains

摘要

A method and apparatus for heat-treating nickel base superalloy articles to provide different properties in different regions of the article. An initially fine grain microstructure is heated such that a portion of the article is held above the gamma ' solvus temperature long enough to provide a coarse grain microstructure while the remainder of the article remains below the gamma ' solvus temperature and retains the fine grain microstructure. The coarse grain microstructure provides a reduced rate of fatigue crack growth rate while the fine grain microstructure retains good tensile properties. The invention is particularly applicable to the fabrication of turbine disks for gas turbine engines.