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Weldability and liquation cracking behavior of ZhS6U superalloy during electron-beam welding

  • Arash Khakzadshahandashti
  • Mohammad Reza RahimipourEmail author
  • Kourosh Shirvani
  • Mansour Razavi
Article

Abstract

The weldability of the ZhS6U nickel-based superalloy, which is prone to solidification cracking during electron-beam welding (EBW) repair processes, was investigated. The effects of two different pre-weld heat-treatment cycles on the final microstructure before and after welding were examined. Welds were made on flat coupons using an EBW machine, and the two heat-treatment cycles were designed to reduce γ′ liquation before welding. Microstructural features were also examined by optical and scanning electron microscopy. The results showed that the change in the morphology and size of the γ′ precipitates in the pre-weld heat-treatment cycles changed the ability of the superalloy to release the tensile stresses caused by the matrix phase cooling after EBW. The high hardness in the welded coupons subjected to the first heat-treatment cycle resulted in greater resistance to stress release by the base alloy, and the concentration of stress in the base metal caused liquation cracks in the heat-affected zone and solidification cracks in the weld area.

Keywords

weldability ZhS6U superalloy electron beam welding heat-affected zone liquation cracking pre-weld heat treatment 

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Notes

Acknowledgements

The authors would like to express their appreciation for Mr. Mehdi Talebipoor’s support in this research for the provision of alloys and other laboratory equipment.

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Copyright information

© University of Science and Technology Beijing and Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  • Arash Khakzadshahandashti
    • 1
  • Mohammad Reza Rahimipour
    • 1
    Email author
  • Kourosh Shirvani
    • 2
  • Mansour Razavi
    • 1
  1. 1.Department of CeramicMaterials and Energy Research CenterKarajIran
  2. 2.Department of Material and Renewal EnergyIranian Research Organization for Science and Technology (IROST)TehranIran

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