Advertisement

KSME International Journal

, Volume 16, Issue 8, pp 1109–1116 | Cite as

Characteristics of fatigue crack initiation and fatigue strength of nitrided lCr-lMo-0.25V turbine rotor steels

  • Chang-Min Suh
  • Byung-Won Hwang
  • Ri Ichi Murakami
Article

Abstract

To investigate the effect of nitriding layer on both fatigue crack initiation and fatigue life, turbine rotor steel (lCr-IMo-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-Vickers 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.

Key Words

Nitriding Fish-Eye Crack Fatigue Strength Fatigue Crack Initiation 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Fuchs, H. O. and Stephens, R. I., 1980,Metal Fatigue in Engineering, John Wiley & Sons, Pub., pp. 27–34.Google Scholar
  2. Gabetta, G. and Torri, L., 1992, “Crack Nucleation and Propagation in Blade Steel Material,”Fatigue Fracture Engineering Materials Structure, Vol. 15, No. 11, pp. 1101–1111.CrossRefGoogle Scholar
  3. Genel, K. and Demirkol, M., 1999, “Effect of Case Depth on Fatigue Performance of AISI 8620 Carburized Steel,”International Journal of Fatigue, 21, pp. 207–212.CrossRefGoogle Scholar
  4. Genel, K., Demirkol, M. and Capa, M., 2000, “Effect of Ion Nitriding on Fatigue Behavior of AISI 4140 Steel,”Materials Science & Engineering, A279, pp. 207–216.CrossRefGoogle Scholar
  5. Gustavsson, A. I. and Melander, A., 1992, “Fatigue Limit Model for Hardened Steels,”Fatigue Fracture Engineering Materials Structure, Vol. 15, No. 9, pp. 881–894.CrossRefGoogle Scholar
  6. Kwak, B. M. and Gil, Y. J., 1985, “An Indirect Experimental Method for the Determination of Mechanical Properties of Ion-nitrided Layer and Residual Stress Distribution,”Transaction of the Korean Society of Mechanical Engineers, Vol. 9, No. 2, pp. 240–249.Google Scholar
  7. Lankford, J., 1997, “Initiation and Early Growth of Fatigue Cracks in High Strength Steel,”Engineering Fracture Mechanics, Vol. 9, pp. 617–624.CrossRefGoogle Scholar
  8. Magnusson, L., 1973, “Low Cycle Behavior of Case Hardened Steel,” Mechanisms of Deformation and Fracture, pp. 105–110.Google Scholar
  9. Murakami, Y., 1989, “Effect of Small Defects and Nonmetallic Inclusions on the Fatigue Strength of Metals,”JSME International Journal, Vol. 32, No. 2, pp. 167–180.Google Scholar
  10. Murakami, Y. and Usuki, H., 1989, “Prediction of Fatigue Strength of High-Strength Steels Based on Statistical Evaluation of Inclusion Size,”Journal of JSME, A55, No. 510, pp. 213–221.Google Scholar
  11. Murakami, Y., Kodama, S. and Konuma, S., 1989, “Quantitative Evaluation of Effects of Non-metallic Inclusions on Fatigue Strength of High Strength Steel. I: Basic Fatigue Mechanism and Evaluation of Correlation between the Fatigue Fracture Stress and the Size and Location of Non-metallic Inclusions,”International Journal of Fatigue, Vol. 11, No. 5, pp. 291–298.CrossRefGoogle Scholar
  12. Qian, J. and Fatemi, A., 1995, “Cyclic Deformation and Fatigue Behavior of Ion-Nitrided Steel,”International Journal of Fatigue, Vol. 17, No. 1, pp. 15–24.CrossRefGoogle Scholar
  13. Suh, C. M. and Kitagawa, H., 1987, “Crack Growth Behavior of Fatigue Microcracks in Low Carbon Steels,”Fatigue Fracture Engineering Materials Structure, Vol. 9, No. 6, pp. 409–424.CrossRefGoogle Scholar
  14. Suh, C. M., Kim, K. R. and Lee, D. W., 1999, “Fatigue Strength of TiAIN Ceramic Coated lCr-lMo-0.25V Steel at Elevated Temperatures,”International Journal of Ocean Engineering and Technology, Vol. 1, No. 1, pp. 69–76.Google Scholar
  15. Yamamoto, K., et al., 1975, “The Comparison of Properties in Iron-nitrided and un-nitrided Specimen,”Japanese Metallic Material, Vol. 15, No. 7, pp. 26–37.Google Scholar

Copyright information

© The Korean Society of Mechanical Engineers (KSME) 2002

Authors and Affiliations

  • Chang-Min Suh
    • 1
  • Byung-Won Hwang
    • 1
  • Ri Ichi Murakami
    • 2
  1. 1.Department of Mechanical EngineeringKyungpook National UniversityTaeguKorea
  2. 2.Department of Mechanical EngineeringTokushima UniversityTokushimaJapan

Personalised recommendations