800H合金长时间蠕变下的显微组织

The Microstructure of Incoloy 800H after Long-time Creep

对低负荷长时间蠕变试验下800H合金显微组织的研究表明:空洞在晶界M_(23)C_6碳化物的一侧形成,微裂纹通过一连串这样的小空洞而发展;晶界M_(23)C_6碳化物和相邻两晶粒之一有共格关系而与另一晶粒无共格界面,共格界面强化了晶界,这一强化作用可用蠕变激活能的提高来说明,晶界还有G相析出,但未发现合金中有γ'相的形成。合金能长时间保留网状的位错结构,晶界碳化物附近有位错塞积,亚晶界结构发展不充分,这与典型的回复蠕变是不同的。

The microstructural change of Incoloy 800H after creep tests with low loads and long rupture time has been inVestigated. Cavities nucleate at One side of M_(23)C_6 carbide particles on grain boundaries. Microcrack propagate hy passing throung a string of these cavities. M_(23)C_6 carbide particles on grain broudaries have a coherent relationship with one of both neighbouring grains, so grain boundaries are strengthened, and the strengthening effect can be estimated for enhanced activation energy. G prase precipitation can be observed on grain boundaries, but no γ' phase particles can be found. Dislocation substructure is different from the typical recovery creep. Dislocation piles appeare near M_(23)C_6 carbide particles on grain boundaries. Subgrain structure poorly develope and network distribution of dislocation can remain after relative long creep.