Measurement of Stress Distribution Near Fatigue Crack in Ultra-Fine Grained Steel by Synchrotron Radiation

Abstract:

Single-edge-notched specimens of ultrafine-grained steel were fatigued. The mean grain size of the steel is about 2 micrometers. Propagation behavior of fatigue cracks was observed with the crack closure. The resistance of the crack propagation of ultrafine-grained steel was larger than that of conventional steels. The crack closure acted as an important role for the larger resistance of fatigue crack propagation. After fatigue tests, stress distribution near the fatigue crack was measured by monochromatic X-rays from synchrotron radiation. The irradiated area was 100 µm x 100 µm. Residual and loading stress distributions ahead of the crack tip and on the crack wake was measured at the maximum stress intensity factor and zero applied load. The stress was determined by sin2ψ method. The measured stress was compared with the value calculated by FEM and the fatigue crack propagation model. The stress distribution at the maximum load and residual stresses agreed very well with the calculated results. The crack opening stress calculated by the residual stresses agreed with the experimental result.

• Periodical: Materials Science Forum (Volumes 490-491)
• Pages: 118-123
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.490-491.118
• Online since: July 2005
• Authors: Yoshiaki Akiniwa, Keisuke Tanaka, Hidehiko Kimura
• Keywords: Crack Closure, Crack Propagation, Fatigue Crack, Finite Element Model (FEM), Residual Stress, Simulation, Synchrotron, Ultrafine Grained Steel

References

[1] H. Mabuchi, T. Hasegawa and T. Ishikawa, ISIJ Int., Vol. 39 (1999), p.477.

[2] T. Ishikawa, Y. Nomiyama, Y. Hagiwara, H. Yoshikawa, S. Oshita and H. Mabuchi, Proc. 16th OMAE Materials Engineering ASME, Vol. 3 (1995), p.357.

[3] T. Ishikawa, Proc. 24th Symp. Fatigue (1998), p.157.

[4] H. Kimura, Y. Akiniwa, K. Tanaka, J. Kondo and T. Ishikawa, Mater. Sci. Res. Inter., Special Tech. Publ., Vol. 1 (2001), p.117.

[5] The Soci. Mater. Sci., Japan, Standard Method for X-Ray Stress Measurement, The Soci. Mater. Sci., Japan, Kyoto (1997) (in Japanese).

[6] E. Kröner, Zeit. Physik, 151 (1958), p.504.

[7] A. E. Lord, Jr. and D. N. Beschers, J. Appl. Phys. 36 (1865), p.1620.

[8] J. C. Newman, Jr, ASTM Special Tech. Publ., 748 (1981), p.53.

[9] Y. Akiniwa, K. Tanaka and N. Taniguchi, Fatigue Fract. Engng Mater. Struct., 11 (1988), p.343.

[10] H. Tada, P. C. Paris and G. R. Irwin, The Stress Analysis of Cracks Handbook, 2. 32 (1974) Del. Res. Corp., Hellertown, Pennsylvania.