Journal of Mechanical Science and Technology

The Korean Society of Mechanical Engineers (대한기계학회)
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Characteristics of Fatigue Crack Initiation and Fatigue Strength of Nitrided 1 Cr- 1Mo-0.25V Turbine Rotor Steels

  • Suh, Chang-Min (Department of Mechanical Engineering, Kyungpook National University) ;
  • Hwang, Byung-Won (Department of Mechanical Engineering, Kyungpook National University) ;
  • Murakami, Ri-Ichi (Department of Mechanical Engineering, Tokushima University)
  • Published : 2002.08.01
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Abstract

To investigate the effect of nitriding layer on both fatigue crack initiation and fatigue life, turbine rotor steel ( IC.- 1Mo-0.25V steel) specimens were nitrided by the nitemper method and then put to a rotary bending fatigue test at room and elevated temperatures. In nitriding, temperature and time were controlled to obtain a different nitrided thickness. Microstructure analysis, micro-Victors hardness test, and scanning electron microscope observation were carried out for evaluating experiments. In results, the fatigue cracks of nitrided specimens were initiated at inclusion near the interface between nitrided layer and substrate, which showed fish-eye type appearance in fractograph. The fatigue life of nitrided specimens at every temperature was prolonged compared to that of the non-nitrided. However, there was not observable improvement in fatigue characteristics with the increase of a nitrided thickness.

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