Effect of thermal exposure on microstructure and nano-hardness of broached Inconel 718

Zhe Chen, Ru Lin Peng, Pajazit Avdovic, Jinming Zhou, Johan Moverare, Fredrik Karlsson, Sten Johansson

Research output: Chapter in Book/Report/Conference proceedingPaper in conference proceedingpeer-review

8 Citations (SciVal)

Abstract

Inconel 718 is a high strength, heat resistant superalloy that is used extensively for components in hot sections of gas turbine engines. This paper presents an experimental study on the thermal stability of broached Inconel 718 in terms of microstructure and nano-hardness. The broaching process used in this study is similar to that used in gas turbine industries for machining fir-tree root fixings on turbine discs. Severe plastic deformation was found under the broached surface. The plastic deformation induces a work-hardened layer in the subsurface region with a thickness of similar to 50 mu m. Thermal exposure was conducted at two temperatures, 550 degrees C and 650 degrees C respectively, for 300 h. Recrystallization occurs in the surface layer during thermal exposure at 550 degrees C and alpha-Cr precipitates as a consequence of the growth of recrystallized delta phases. More recrystallized grains with a larger size form in the surface layer and the alpha-Cr not only precipitates in the surface layer, but also in the sub-surface region when the thermal exposure temperature goes up to 650 degrees C. The thermal exposure leads to an increase in nano-hardness both in the work-hardened layer and in the bulk material due to the coarsening of the main strengthening phase gamma ''.
Original languageEnglish
Title of host publicationEurosuperalloys 2014 - 2nd European Symposium on Superalloys and their Applications
PublisherEDP Sciences
Pages08002
Volume14
DOIs
Publication statusPublished - 2014
Event2nd European Symposium on Superalloys and their Applications - Giens, FRANCE
Duration: 2014 May 122014 May 16

Publication series

Name
Volume14
ISSN (Print)2261-236X

Conference

Conference2nd European Symposium on Superalloys and their Applications
Period2014/05/122014/05/16

Subject classification (UKÄ)

  • Materials Engineering

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