| 摘要 |
A method of forging to impart a critical amount of retained strain is described for Ni-base superalloys, particularly those which comprise a mixture of gamma and gamma ' phases, and most particularly those which contain at least about 40 percent by volume of gamma '. This forging method harnesses nucleation-limited recrystallization, a phenomenon which has been known in the past to produce uncontrolled, non-uniform Critical grain growth, to produce forged articles having a uniform average grain size in the range of about 90-120 microns. The method comprises the selection of a forging preform formed from a Ni-base superalloy. Isothermal subsolvus forging is then used to form a precursor forging which has a near-net shape. The precursor forging is then forged using relatively high strain rate techniques, such as hammer forging, hot die forging or room temperature forging, to impart all or some portion of it with a critical amount of retained strain energy. The forging is then given a final subsolvus soak and supersolvus anneal to form the uniform grain structure.
|
