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Desulfurization Mechanism of K4169 Superalloy Using CaO Crucible in Vacuum Induction Melting Process

  • Kewei Xie
  • Bo Chen
  • Mengshu Zhang
  • Zhanhui Du
  • Xiangdong Zha
  • Shujiang Geng
  • Kui Liu
Conference paper

Abstract

The desulfurization experiments of K4169 superalloy were carried out in vacuum induction furnace with the thermodynamically stable CaO crucible. It was found that the sulfur concentrations did not change with the melting time when the melt mainly contained Ni, Cr, Fe and Nb element before Al or Ti addition. But the sulfur contents in the melt decreased rapidly to 6 ppm after 0.6% Al element addition. Adding Ti had a similar effect on desulfurization except for the ultimate sulfur content. The contact surface of CaO crucible with melt was studied using XRD, SEM and EPMA. The results showed that the distribution of sulfur element on the surface was coincident with calcium element. A small amount of calcium-aluminate (3CaO·Al2O3) and calcium titanium trioxide (CaTiO3) were detected at inner surface of crucible when Al and Ti were added into the melt respectively. About 20 μm depth layer of CaS desulfurization resultant was founded from the interface of the CaO crucible. The desulfurization reaction at interface are deduced to 3CaO + 2[Al]Ni + 3[S]Ni = 3CaS + Al2O3, and 3CaO + [Ti]Ni + 2[S]Ni = 2CaS + CaTiO3. In the condition of Al addition, 3CaO·Al2O3 is produced from Al2O3 and CaO crucible which has a low melting point and can be transferred easily, so it is the feasible reason to accelerate the desulfurization reaction greatly. Thermodynamics calculation and discussion about the reaction between the inner surface of CaO crucible and liquid metal has been done.

Keywords

K4169 CaO crucible Desulfurization Vacuum induction melting 

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Copyright information

© Springer Nature Singapore Pte Ltd. 2018

Authors and Affiliations

  • Kewei Xie
    • 1
    • 2
  • Bo Chen
    • 2
  • Mengshu Zhang
    • 2
  • Zhanhui Du
    • 2
  • Xiangdong Zha
    • 2
  • Shujiang Geng
    • 1
  • Kui Liu
    • 2
  1. 1.School of MetallurgyNortheastern UniversityShenyangChina
  2. 2.Institute of Metal Research, Chinese Academy of SciencesShenyangChina

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