Journal of Korea Foundry Society (한국주조공학회지)

Korea Foundry Society (한국주조공학회)
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Effects of Process Parameter on Alpha-Case Formation of Ti and TiAl castings

Ti 및 TiAl 주조재의 ${\alpha}$-case 형성에 미치는 공정변수에 대한 영향

  • Lee, Sang-Hwa (Department of Metallurgical Engineering, Donga University) ;
  • Kim, Myoung-Gyun (Department of Advanced Materials Engineering, Sungkyunkwan University) ;
  • Sung, Si-Yuong (Department of Advanced Materials Engineering, Sungkyunkwan University) ;
  • Kim, Young-Jig (Department of Advanced Materials Engineering, Sungkyunkwan University)
  • 이상화 (동아대학교 금속공학과) ;
  • 김명균 (성균관대학교 신소재공학과) ;
  • 성시영 (성균관대학교 신소재공학과) ;
  • 김영직 (성균관대학교 신소재공학과)
  • Published : 2003.06.20
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Abstract

The main purpose of this study is to investigate the effects of process parameter on alpha-case formation of Ti and TiAl castings. The previous studies showed that the molten titanium is excessively reactive to the refractory oxide mold, resulting in alpha-caes of the titanium castings regardless of composition of titanium alloys. However, the behavior of the alpha-case formation of TiAl alloy is not consistent with conventional titanium alloy. In order to investigate the alpha-case formation of Ti and TiAl castings with process parameter, especially the associated factors of investment mold such as mold material, binder and mold preheating temperature. An attempt has been made to characterize the alpha-case of titanium casting by using optical microscope, EDS, XRD, EMPA and hardness profiles. The formation of the alpha-case on the surface of pure titanium during investment casting was rather by that of solid solution with metallic element from mold material. The required mold strength was obtained with $CaZrO_3$ because of the possibility of using water soluble binder. However, the separation phenomenon between facing and back-up mold materials should be considered. The interfacial reaction of TiAl alloy showed different behavior from that of pure titanium and $Al_2O_3$ was best mold materials. The effect of binder as well as mold material on the formation of alpha-case was significant.

Keywords

References

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