Variation of Rotating Bending Fatigue Characteristics by UNSM on Ti-6Al-4V

Ti-6Al-4V재의 UNSM처리에 의한 회전굽힘피로특성변화

Suh, Chang-Min;Pyoun, Young-Sik;Suh, Min-Soo

  • Received : 2011.08.18
  • Accepted : 2010.12.23
  • Published : 2011.12.31


In order to analyze feasibility of replacing a conventional 6-mm Ti bar with a 5-mm bar, a series of rotating bending fatigue tests were carried out on Ti-6Al-4V bars by strengthening the fatigue performance using a special technique called UNSM (Ultrasonic Nanocrystal Surface Modification). The results of S-N curves clearly showed that the performance of the 5-mm titanium specimen was similar to that of the 6-mm specimen when the UNSM treatment was applied. The 5-mm treated specimen converged with small scattering band into the linear line of the non-treated 6-mm one. Below the fatigue life of $10^5$ cycles, the UNSM treatment did not show any significant superiority in the bending stress and fatigue life. However, over the fatigue life of $10^5$ cycles, the effect of UNSM was superior for each fatigue life, and the bending stress became longer and higher than that of the untreated one. In the case of 6-mm Ti-bar with UNSM, the fatigue limit was about 592 MPa, and there was fatigue strength increase of about 30.7% at the fatigue life of $10^4$ cycles compared to the untreated 6-mm bar. Therefore, the compressive residual stress made by the UNSM in Ti-6Al-4V increased the fatigue strength by more than 30%.


Rotating bending fatigue test;S-N curve;Ultrasonic nanocrystal surface modification technology;Compressive residual stress


  1. Altenberger, I. (2005). "Deep Rolling - The Past, The Present and The Future", Proc. 9th Int. Conf. on Shot Peening, pp 144-155.
  2. Chai, G. (2006). "The Formation of Subsurface Non-Defect Fatigue Crack Origins", International Journal of Fatigue. Vol 28-11, pp 1533-1539.
  3. Ochi, Y., Matsumura, T., Sasaki, R., Masaki,. K., Sakai, T. and Sano, Y. (2011). "Effects of Laser Peening Treatment Without Protective Coation on High Cycle Fatigue Property of Ti-6Al-4V alloy", 5th International conference on Very High Cycle Fatigue, pp 369-374.
  4. Petit, J., Christine Sarrazin-Baudoux and Martinez, J. (2007). "Very High Cycle Fatigue Behavior of Ti6246 Alloy in Air and in High Vacuum", 4th International Conference on Very High Cycle Fatigue, pp 399-408.
  5. Prevey, P. and Jayaraman, N. (2005). "Overview of Low Plasticity Burnishing for Mitigation of Fatigue Damage Mechanisms", Proc. 9th Int. Conf. on Shot Peening, pp 267-272.
  6. Suh, C.M., An, Y.D., Pyun, Y.S., Cho, L.H. and Suh, M.S. (2011). "Improvement of VHCF Properties of AISI 1045, 4137, 52100 & H13 steel by UNSM treatment", 2011년도 한국해양과학기술협의회 공동학술대회, pp 1574-1579.
  7. Suh, C.M., Kim, M.H., Baek, U.B., Pyun, Y.S., Kim, C.S. and Chi, C.H. (2010a). "A Stduy on The Alternative Technonogy Using UNSM Instead of The Persetting Method for Torsion Bar", International journal of modern physics B, Vol 24, Nos 15-16, pp 2435-2440.
  8. Suh, C.M. and Kitagawa, H. (1985), "Fatigue Microcracks in a Low Carbon Steel", Fatigue Fract. Engng. Mater. Struct., Vol 8-2, pp 193-203.
  9. Suh, C.M. and Kitagawa, H. (1987), "Crack Growth Behaviour of Fatigue Microcracks in Low Carbon Steels" Fatigue Fract. Engng. Mater. Struct, Vol 9-6, pp 409-424.
  10. Suh, C.M., Lee, M.H. and Pyoun, Y.S. (2010b). " Fatigue Characteristics of SKD-61 by Ultrasonic Nanocrystal Surface Modification Technology Under Static Load Variation", International journal of modern physics B, Vol 24, Nos 15-16, pp 2645-2650.
  11. Suh, C.M., Song, G.H. Suh, M.S. and Pyoun, Y.S. (2007). "Fatigue and Mechanical Characteristic of Nano-Structured Tool Steel by Ultrasonic Cold Forging Technology", Materials Science and Engineering A 443, pp 101-106.
  12. Thomas, M.B. (2002). "High Cycles Fatigue (HCF) Science and Technology Program 2001 Annual Report", AFRL-PR-WPTR-2002-2060.
  13. Watanabe, Y., Hasegawa, N. and Duchazeaubeneix J.M. (2003). "Effect of Ultrasonic Shot Peening on Fatigue Strength of High Strength Steel", Proc. 8th Int. Conf. on Shot Peening, pp 306-310.
  14. 편영식, 박정현, 조인호, 김창식, 서창민 (2009). "초음파 나노표면개질기술의 특성과 활용방안 연구", 대한기계학회논문집 (A), 33-3, pp 190-195.


Supported by : 한국연구재단