Anisotropy Studies on Hot-forged $\gamma$-TiAl Alloys

열간단조된 $\gamma$-TiAl 합금의 이방성에 관한 연구

  • Lee, Jae-Seung (Department of Materials System Engineering, Kumoh National Institute of Technology) ;
  • Park, No-Jin (Department of Materials System Engineering, Kumoh National Institute of Technology) ;
  • Kim, Seong-Jin (Department of Materials System Engineering, Kumoh National Institute of Technology) ;
  • Kim, Seung-Eon (Department of Materials processing, Korea Institute of Machinery and Materials) ;
  • O, Myeong-Hun (Department of Materials System Engineering, Kumoh National Institute of Technology)
  • 이재승 (금오공과대학교 신소재시스템공학부) ;
  • 박노진 (금오공과대학교 신소재시스템공학부) ;
  • 김성진 (금오공과대학교 신소재시스템공학부) ;
  • 김승언 (한국기계연구원 재료공정연구부) ;
  • 오명훈 (금오공과대학교 신소재시스템공학부)
  • Published : 2000.09.01

Abstract

The texture evolution during isothermal forging and subsequent heat treatment in Ti-48.5at%Al-0.6at%Mo alloy was investigated. Especially, in the present study, research interest was focused on the interrelation between lamellar volume fraction and textures varied with the change of heat-treated time and temperature. It was found that texture components having ND┴{302) and TD$\perp${100} with minor TD$\perp${111} were developed by isothermal forging. In addition, when the followed heat-treatment time and temperature increased from $1330^{\circ}C$/10h to $1350^{\circ}C$/20h respectively, both the lamellar volume fraction and the intensity of textures mentioned above also gradually increased. However, the tensile elongation at room temperature decreased oppositely, as the lamellar volume fraction increased. These results suggested that tensile properties of $\gamma$-TiAl with the nearly lamellar microstructure at room temperature were affected more strongly by the microstructural features such as lamellar volume fraction rather than by textures.

본 논문에서는 Ti-48.5at%Al-0.96at%Mo 조성을 갖는 $\gamma$-TiAl 합금은 항온 단조 및 후속 조직제어 열처리 시 발달하는 집합조직의 변화에 관해 연구하였다. 특히, 동적 재결정 후 조직제어 열처리 온도와 시간의 증가에 따라 발생하는 lamellar volume fraction 과 집합조직 변화에 주목하여 관찰하였다. 동적 재결정 후 집합조직은 ND$\perp${302) 선분과, TD$\perp${100) 및 이에 비해 상대적으로 다소 약한{111) 성분들이 발달하였으며, 열처리 온도와 시간이 증가함에 따라 lameller volume fraction 은 증가했고 동일한 성분의 집합조직도 점차 강하게 발달함을 알 수 있었다. 하지만 상온인장시험 결과는 lameller volume fraction이 증가할수록 낮은 상온 연신을 보였는데, 이는 준 층상조직을 갖는 $\gamma$-TiAl합금의 상온인장특성이 집합조직의 영향보다는 lameller volume fractio과 같은 미세조직 특성에 더욱 강하게 영향을 받기 때문인 것으로 판단된다.

Keywords

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