|
|
|
| HOT CORROSION OF A Ni-BASE SUPERALLOY IN SO~2/AIR ENVIRONMENT UNDER APPLIED LOAD |
| Hu Gengxiang Zhou Lang Zhang Yuanhu(Shanghai Jiao Tong University) |
|
|
|
|
Abstract Hot corrosion of GH33 Ni-base superalloy was investigated by conducting creep tests in an environmental chamber circulated with SO_2-air mixed gas. Analyses were carried out on the outer surfaces, longitudinal sections and fracture surfaces of the tested specimens, including specimens tested to rupture or interrupted at various extents of creep strain. The results were compared with those tested in air.It was found that both in air and in SO_2/air environment a Cr-riched oxide scale was formed initially, which protected the grain boundaries and matrix from being attacked by SO_2. Therefore, as long as the protective scale was not ruptured by the creep deformation, SO_2/air and air played the same role in corrosion, i. e. oxidation is the principal process. But after the deformation increased to a certain extent, intergranular cracks initiated on the specimen surface and sulfur attack occurred. Molten Ni-Ni_3S_2 eutectics formed at grain boundaries which led to catastrophic corrosion and premature failure of the specimen.The mechanism of such corrosion process is discussed. It is suggested that the interaction of hot corrosion and creep of superalloy greatly accelerated the failure process and attention should be paid to this problem during engineering design or material application.
|
|
Received: 25 February 1987
|
[1] Hocking, M. G.: Vasantasree, V., Corrosion Science.,16, 279 (1976)
[2] Sidky, P. S.; Hocking, M. G., Behaviour of High Temperature Alloys in Agressive Enviroments., 497 (1979)
[3] Chang, D. R.; Nemoto, R.: Wagner, Jr. J. B.. Met. Trans. A 7A, 803(1976)
[4] Worrell, L.: Rao. B. K., High Temperature Corrosicn 297(1983)
[5] Hancock. P., International Congress on Metallic Corrosicn 193 (1962) |
| No Suggested Reading articles found! |
|
|
Viewed |
|
|
|
Full text
|
|
|
|
|
Abstract
|
|
|
|
|
Cited |
|
|
|
|
| |
Shared |
|
|
|
|
| |
Discussed |
|
|
|
|
