Journal of the Korean Society for Heat Treatment (열처리공학회지)

The Korean Society for Heat Treatment (한국열처리공학회)
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Creep Characteristics of Ti-6Al-4V Alloy Surface Modified by Plasma Carburized/CrN Coating

복합처리(Carburized/CrN Coating)로 표면개질된 Ti-6Al-4V합금의 크리프 특성

  • Park, Yong-Gwon (Department of Materials Engineering, Chungbuk National University) ;
  • Park, Jung-Ung (Division of Advanced Materials Engineering, Kongju National University) ;
  • Wey, Myeong-Yong (Department of Materials Engineering, Chungbuk National University)
  • Received : 2005.05.02
  • Accepted : 2005.05.20
  • Published : 2005.05.30
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Abstract

The effects of duplex-treatment of plasma carburization and CrN coating onto Ti-6Al-4V alloy on its creep properties were investigated by means of a constant stress creep tester. Applying duplex-treatment, specimens having an inner carburized layer of about $150{\mu}m$ in depth and outer CrN layer of about $7.5{\mu}m$ in thickness were prepared. The hardness of duplex-treatment surface was about 1,960 VHN. It also appeared that the duplex-treatment improved the roughness of the surface significantly; $Ra=0.045{\mu}m$ for treated alloy while $Ra=0.321{\mu}m$ for untreated alloy. The steady-state creep behaviors were investigated in a temperature range of $510{\sim}550^{\circ}C$ ($0.42{\sim}0.44T_m$) under an applied stress range of 200~275 MPa. The stress exponent, n, was derived assuming the power law creep behavior. The surface treatment showed a decrease in a value from 9.32 (untreated) to 8.79 (treated). Also the activation energy obtained from an Arrhenius plot increased from 238 to 257 kJ/mol.

Keywords

Acknowledgement

Supported by : 충북대학교

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