GH4706合金的动态再结晶与晶粒控制*

采用双锥压缩实验结合有限元数值模拟, 研究了变形温度、变形量对GH4706合金动态再结晶(DRX)与η相的影响, 分析了发生DRX的临界条件, 探讨了利用η相细化晶粒的方法。结果表明: GH4706合金DRX机制为应变诱发的不连续原始晶界弓出; 临界DRX温度(T_DRX)为975℃, 而临界变形量(ε_DRX)则取决于变形温度与变形生热。由于η相的溶解温度近于T_DRX, 当合金在略低于T_DRX温度变形时, 有部分η相残留, 具有阻碍亚晶界或晶界迁移的效果。由此, 对GH4706合金在变形温度低于T_DRX条件下进行大变形, 可利用η相与再结晶的交互作用, 细化合金晶粒。

Dynamic Recrystallization Behavior and Grain Size Control of GH4706 Superalloy

The influence of deformation temperature and strain on the microstructure of GH4706 superalloy was studied by means of double-cone samples compression combined with finite element numerical (FEM) simulation. The results show that the dynamic recrystallization (DRX) mechanism of GH4706 superalloy is a discontinuous process associated with a strain induced grain boundaries bulging leading to the formation of nuclei. It is found that the critical temperature (T_DRX) is 975℃, while the critical strain (ε_DRX) of DRX depends on both the solve of η phase and deformation generating heat. When the deformation temperature is slight lower than the T_DRX, η phase will be partially retained in the alloy, which then hinders the migration of sub-grain or grain boundaries. Therefore, finer grain of GH4706 superalloy can be obtained by deforming with a larger strain at a temperature below T_DRX.