镍基高温合金GH4698的热变形组织演变机理

采用热模拟等研究方法,对不同变形工艺条件下的GH4698热变形组织演变机理开展了研究。结果表明:高温低速变形有利于动态再结晶进行,材料发生完全动态再结晶的初始变形温度大于1150 ℃;从工程角度出发,合金初始变形温度推荐1200 ℃,采用低速变形原则(0.01~0.1 s^-1),为获得相对均匀的锻造组织,终锻温度应高于1050 ℃,锻造过程可多火次完成;经GJB 3782标准推荐多级热处理后,晶粒内部存在大量弥散分布的γ′纳米析出物,起到良好的析出强化作用。

Microstructure evolution mechanism of nickel-based superalloy GH4698 during hot deformation

Microstructure evolution mechanism of the GH4698 alloy under different deformation conditions was studied by means of thermal simulation. The results show that high temperature and low speed deformation is conducive to dynamic recrystallization, and the initial deformation temperature of fully dynamic recrystallization is higher than 1150 ℃. From the engineering point of view, the initial deformation temperature of the alloy is recommended to be 1200 ℃, and the low speed deformation principle (0.01-0.1 s^-1) is adopted. In order to obtain relatively uniform forging microstructure, the final forging temperature should be higher than 1050 ℃, and the forging process can be completed in multiple heats. After GJB 3782 standard recommended multistage heat treatment, there are a lot of dispersed particles in the grain γ′ nano precipitates play a good role in precipitation strengthening.