| About this Abstract |
| Meeting |
10th International Symposium on Superalloy 718 and Derivatives (2023)
|
| Symposium
|
Superalloy 718 and Derivatives
|
| Presentation Title |
Hot Corrosion Behavior of a GH4720Li Disk Superalloy at 700℃ |
| Author(s) |
Teng An, Fangzhen Duan, Yu Gu, Yuting Shi, Di Wang, Jinglong Qu, Zhongnan Bi, Jinhui Du |
| On-Site Speaker (Planned) |
Teng An |
| Abstract Scope |
The nickel-based superalloy disk components in the turbine sections were subjected to Type II hot corrosion damage in the sulfur-containing salt contaminants at 650℃–750℃. The alloy GH4720Li with different grain sizes was corroded in a mixture of sulfates (25% NaCl + 75% Na2SO4) at 700℃ for 200 h, and the microstructure evolution was investigated. The experimental results showed that when the grain size increased from 15.9 to 127 μm, the mass loss decreased by 96%, and the corrosion layer thickness decreased by 44%. The hot corrosion resistance increased with the increasing grain size, and the corrosion failure mechanisms changed from pitting corrosion to uniform corrosion. The corrosion layer comprised NiCr2O4, Al2O3, CoO, TiO, Ni3S2, and CoS2. The oxide layer, Ni/Co-rich layer, and S-rich layer were stratified and sequentially located on the alloy GH4720Li surface. The corrosion behavior was accelerated by the triangular grain boundaries (GBs) and γ´ phase, the segregation behavior of Cr elements in the GBs, as well as the γ´ phase formation promoted the tendencies for pit nucleation in the fine-grained structure. In contrast, the Ni/Co-rich layer provided better resistance to hot corrosion and was easier to form on the surface of the coarse-grained structure. The sulfide-oxidation cycle mechanism could well describe the hot corrosion behavior of the disk superalloy. |
| Proceedings Inclusion? |
Definite: At-meeting proceedings |