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STUDY ON THE PRECIPITATION AND DISSOLUTION OF sigma PHASE IN A HOT CORROSION RESISTANCE CAST NICKLE BASE SUPERALLOY
Hou Jieshan; Guo Jianting; Yuan Chao; Zhou Lanzhang
Corresponding AuthorZhou Lanzhang(lzz@imr.ac.cn)
2016-02-11
Source PublicationACTA METALLURGICA SINICA
ISSN0412-1961
Volume52Issue:2Pages:168-176
AbstractThe experimental alloy is designed and employed in high-performance industrial gas turbines as low-pressure turbine blades, working in temperature range of 750 similar to 900 degrees C. The alloy contains high levels of refractory elements in order to increase the high-temperature mechanical properties. However, this can make the alloy prone to the formation of sigma phase during service, which could deteriorate the properties further if the fraction of sigma phase exceeds the safety allowances. In this study, the formation of sigma phase during long-term thermal exposure, dissolution of the sigma phase during rejuvenation process and their influence on stress-rupture properties of a hot-corrosion resistant nickel base superalloy have been investigated. During long-term thermal exposure at 800 similar to 900 degrees C for up to 1 x 10(4) h, the sigma phase formation is mainly in dendrite cores with a few at interdendritic regions. As the aging temperature increases, the precipitation rate of sigma phase increases and the incubation time for nucleation of sigma phase decreases. From the kinetic analysis, the sigma phase form firstly in the vicinity or on the M23C6 in dendrite cores with the strong segregation of W, Cr and Co. The calculated activation energies of a formation show that the early stage is related to Co and Cr diffusions and the steady stage is related to Mo diffusion. During solid solution process at 1000 similar to 1170 degrees C the sigma phase precipitated during long-term thermal exposure dissolves to gamma matrix. As the solid solution temperature is higher, the dissolution of a phase becomes faster. Moreover, the sigma phase does not embrittle the alloy. The reheat treatment of the alloy leads to the dissolution of precipitated sigma phase and further prolongs the stress-rupture life efficiently.
Keywordnickel base superalloy long-term exposure precipitation dissolution sigma phase
Funding OrganizationNational Natural Science Foundation of China
Indexed BySCI
Language英语
Funding ProjectNational Natural Science Foundation of China[30170302] ; National Natural Science Foundation of China[51571191]
WOS Research AreaMetallurgy & Metallurgical Engineering
WOS SubjectMetallurgy & Metallurgical Engineering
WOS IDWOS:000371849600006
PublisherSCIENCE PRESS
Citation statistics
Document Type期刊论文
Identifierhttp://ir.imr.ac.cn/handle/321006/121742
Collection中国科学院金属研究所
Corresponding AuthorZhou Lanzhang
AffiliationChinese Acad Sci, Inst Met Res, Shenyang 110016, Peoples R China
Recommended Citation
GB/T 7714
Hou Jieshan,Guo Jianting,Yuan Chao,et al. STUDY ON THE PRECIPITATION AND DISSOLUTION OF sigma PHASE IN A HOT CORROSION RESISTANCE CAST NICKLE BASE SUPERALLOY[J]. ACTA METALLURGICA SINICA,2016,52(2):168-176.
APA Hou Jieshan,Guo Jianting,Yuan Chao,&Zhou Lanzhang.(2016).STUDY ON THE PRECIPITATION AND DISSOLUTION OF sigma PHASE IN A HOT CORROSION RESISTANCE CAST NICKLE BASE SUPERALLOY.ACTA METALLURGICA SINICA,52(2),168-176.
MLA Hou Jieshan,et al."STUDY ON THE PRECIPITATION AND DISSOLUTION OF sigma PHASE IN A HOT CORROSION RESISTANCE CAST NICKLE BASE SUPERALLOY".ACTA METALLURGICA SINICA 52.2(2016):168-176.
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