DOI QR코드

DOI QR Code

Improvement of Fatigue Properties in Ultrafine Grained Pure Ti after ECAP(Equal Channel Angular Pressing)

ECAP가공에 의한 초미세립 순수 티타늄의 피로 특성 향상

  • 이영인 (서울산업대학교 대학원 자동차공학과) ;
  • 박진호 (서울산업대학교 대학원 자동차공학과) ;
  • 최덕호 (서울산업대학교 대학원 자동차공학과) ;
  • 최명일 (덴티움(주) 기술연구소) ;
  • 김호경 (서울산업대학교 자동차공학과)
  • Published : 2005.11.01

Abstract

Fatigue life and notch sensitivity of the ultrafine grained pure Ti produced by ECAP was investigated. The ECAPed sample with the true strain of 460$\%$ showed near equiaxed grains with an average size of about 0.3 $\mu$m. After ECAP, the ultimate tensile strength was increased by 60$\%$, while the tensile ductility was decreased by 31$\%$. The ECAPed ultrafine grained pure Ti samples showed high notch sensitivity and significant improvement of high cycle fatigue limit by a factor of 1.67. The ECAPed samples also show high notch sensitivity (K$_{f}$/K$_{t}$ = 0.96). It can be concluded that ECAP is the effective process for achieving high fatigue strength in Ti by increasing its tensile strength through grain refinement

Keywords

Pure Ti;Equal Channel Angular Pressing;Ultrafine Grained Microstructures;Fatigue;Notch Sensitivity;Fatigue Limit

References

  1. Zhu, Y., Lowe, T. and Langdon, T.G., 2004, 'Performance and Applications of Nanostructured Materials Produced by Severe Plastic Deformation,' Scripta Mater., Vol. 51, pp. 825-830 https://doi.org/10.1016/j.scriptamat.2004.05.006
  2. Kuroda, D., Niinomi, M., Morinaga, M., Kato, Y. and Yashiro, T., 1998, 'Design and Mechanical Properties of New ${\beta}$ Type Titanium Alloys for Implant Materials,' Mat. Sci. Eng. A, Vol. 243, pp. 244-249 https://doi.org/10.1016/S0921-5093(97)00808-3
  3. Iwahashi, Y., Horita, Z., Nemoto, M. and Langdon, T.G, 1998, 'The Process of Grain Refinement in Equal-Channel Angular Pressing,' Acta Mater., Vol. 46, pp. 3317-3331 https://doi.org/10.1016/S1359-6454(97)00494-1
  4. Iwahashi, Y., Furukawa, M., Horita, Z., Nemoto, M. and Langdon, T.G, 1998, 'Microstructural Characteristics of Ultrafine-Grained Aluminum Produced Using Equal-Channel Angular Pressing,' Metal. Mat. Trans., Vol. 29A, pp. 2245-2252
  5. Kim, HK., Cho,i ML, Chung, CS. and Shin, DH., 2002, 'Fatigue Crack Growth Behavior in Ultrafine Grained Low Carbon Steel,' KSME Int. J., Vol. 16, No. 10, pp. 1246-1252
  6. A. Y. Vinogradov, V. V. Stolyarov, S. Hashimoto and R. Z. Valiev, Mater. Sci. & Eng. A318, 163-173 (2001) https://doi.org/10.1016/S0921-5093(01)01262-X
  7. Valiev, R.Z., Kozlov, E.V., Ivanov, Y.F, Lian, J., Nazarov, A.A. and Baudelet, B., 1994, 'Deformation Behavior of Ultrafine-Grained Copper,' Acta Metall. Mater., Vol. 42, pp. 2467-2475 https://doi.org/10.1016/0956-7151(94)90326-3
  8. Vinogradov, A., Nagasaki, S., Parian, V., Kitagawa, K. and Kawazoe, N., 1999, 'Fatigue Properties of Fine Grain 5056 Al-Mg Alloy Processed by Equal-Channel Angular Pressing,' NanoStructured Mater., Vol. 11, pp. 925-934 https://doi.org/10.1016/S0965-9773(99)00392-X
  9. Kim, HK., Lee, YI. and Chung, CS., 2005, 'Fatigue Properties of a Fine Grained Magnesium Alloy Produced by Equal Channel Angular Pressing,' Scripta Mater., Vol. 52, pp. 473-477 https://doi.org/10.1016/j.scriptamat.2004.11.007
  10. Stolyarov, V.V., Alexandrov, I.V., Kolobov, Y.R., Zhu, M., Zhu, Y. and Lowe, T., 1999, in Proc. Of the 7th Int. Fatigue Congress, Beijing, P.R. China (Eds: X.R. Wu, Z.G. Wang); Higher Education Press, Beijing, China, p. 1345
  11. Vinogradov, A. and Hashimoto, S., 2003, 'Fatigue of Severely Deformed Metals,' Adv. Eng. Mater., Vol. 5, pp. 351-358 https://doi.org/10.1002/adem.200310078
  12. Turner, N.G. and Roberts, W.T., 1968, 'Fatigue Behavior of Titanium,' Trans AIME, Vol. 242, pp. 1223-1230
  13. Hu, Z. and Cao, S., 1994, 'Relationship between Fatigue Notch Factor and Strength,' Eng. Frac. Mech., Vol. 48, pp. 127-136 https://doi.org/10.1016/0013-7944(94)90149-X
  14. Bouce, B.L. and Ritchie, R.O., 2001, Effect of Load Ratio and Maximum Stress Intensity on the Fatigue Threshold in Ti-6A1-4V,' Eng. Fract. Mech., Vol. 68, pp. 129-147 https://doi.org/10.1016/S0013-7944(00)00099-0
  15. Chung, CS., Kim, JK., Kim, HK. and Kim, WJ., 2002, 'Improvement of High-Cycle Fatigue Life in a 6061 Al Alloy Produced by Equal Channel Angular Pressing,' Mat. Sci. Eng. A, Vol. 337, pp. 39-44 https://doi.org/10.1016/S0921-5093(02)00010-2