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Effect of η phase on mechanical properties of the iron-based superalloy using shear punch testing

Seifollahi, M ; Sharif University of Technology | 2013

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  1. Type of Document: Article
  2. DOI: 10.2355/isijinternational.53.311
  3. Publisher: 2013
  4. Abstract:
  5. In this paper, the shear deformation behavior of A286 Iron-based superalloy was studied with an emphasis on the influence of η phase on shear strength. The η (Ni3Ti phase precipitates at high temperature heat treatment or during services at the expense of gamma prime phase. According to the microstructural features, no evidences of η phase were found at 650 and 720°C. η phase precipitated at 780 and 840°C and the amount of it increased with an increase the time and temperature. Because of using the alloy as fasteners, investigation of shear properties and the influence of η phase on it are indispensable. The shear strength of the alloy with different volume fractions of η was examined. It was found that, with an increase of η volume fraction, the ultimate shear strength decreases. The shear punch fracture surfaces were also examined by the scanning electron microscopy. The fracture surfaces of sheared samples indicated that low and high volume fraction of η phase result in interior cracks and grain boundary decohesion, respectively. In fact, the fracture of weak grain boundary films (η phase produces this kind of decohesive cracking
  6. Keywords:
  7. η phase ; A286 superalloy ; Fracture surface ; High temperature phase transformation ; Shear punch test ; Fracture surfaces ; Grain boundary decohesion ; High temperature heat treatment ; High temperature phase ; High volume fraction ; Microstructural features ; Shear-punch tests ; Ultimate shear strength ; Cracks ; Grain boundaries ; Hydrogen embrittlement ; Mechanical properties ; Microstructural evolution ; Scanning electron microscopy ; Superalloys
  8. Source: ISIJ International ; Volume 53, Issue 2 , 2013 , Pages 311-316 ; 09151559 (ISSN)
  9. URL: https://www.jstage.jst.go.jp/article/isijinternational/53/2/53_311/_article