Development of extra Fine grain structure of Superalloy 718

摘要

The thermomechanical process is commonly used for the manufacturing of the fine grain structure for Inconel 718, but it is energy consumptive and hard to control precisely. In this study, cold forming combined with recrystallized treatment were used as an alternative method for achieving a fine grain structure, wherein proper control of 8 phase formation is quite essential. With the aid of fine uniformly dispersed 5 phase precipitates in the matrix, the rapid growth of recrystallized grains that usually happens at high temperature is substantially retarded. Consequently, a fine recrystallized structure with an average grain size of 2-3μm is obtained, which is much finer than the reported finest grains of 11.2μm obtainable by conventional thermomechanical process.