Effects of surface oxide layers on crack initiation and growth of HSLA steel under cyclic loading in air and in ultrahigh vacuum
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Effects of the thermally grown wustite on the fatigue crack initiation and growth in HSLA steel are evaluated as a function of oxide thickness, strain amplitude, and gaseous environment in the push-pull plastic strain control mode, with special attention being given to the early stage of microcrack initiation. Specimens with a wustite surface layer thermally grown to 0.2 and 0.6 μm thicknesses show predominantly intergranular cracking at plastic strain amplitudes of 5×10−4 and 1×10−3 both in air and in ultrahigh vacuum (UHV), in contrast to the as-polished specimens where slip band cracking is the favoured mode. The cracking mode in the oxide layer is discussed in terms of the strain amplitude and the dislocation behaviour near the oxide/metal interface. The features of microcrack initiation in the oxide layer is not affected by the gaseous environment. Once, however, the surface oxide fractures, the rate of crack growth through the base metal is greatly reduced in UHV.
KeywordsPlastic Strain Oxide Layer Crack Initiation Strain Amplitude HSLA Steel
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- 3.H. J. Gough and D. G. Sopwith, J. Inst. Metals 49 (1932) 93.Google Scholar
- 4.Idem, ibid. 52 (1935) 55.Google Scholar
- 12.W. J. Lee, S. P. Bhat, Y. W. Chung and M. E. Fine, in Proceedings of the 3rd International Conference on Fatigue and Fatigue Thresholds: Fatigue '87, Vol. III, Charlottesville, June 1987, edited by R. O. Ritchie and E. A. Starke, Jr (EMAS, UK, 1987) p. 1211.Google Scholar
- 13.D. Majumdar, Ph. D. Diss., Dept. of Materials Sci. and Eng., Northwestern University, 1983.Google Scholar
- 17.R. F. Mehl and E. F. McCandless, Trans. AIME 125 (1937) 531.Google Scholar
- 20.T. K. G. Swami, Ph.D. Diss., Dept. of Materials Sci. and Eng., Northwestern University, 1981.Google Scholar
- 27.C. V. Cooper, Ph.D. Diss. Dept. of Materials Sci. and Eng., Northwestern University, 1983.Google Scholar
- 29.J. C. Grosskreutz and C. Q. Bowles, in “Environment-Sensitive Mechanical Behavior”, edited by A. R. C. Westwood and N. S. Stoloff (Gordon and Breach, New York/London, 1966) p. 67.Google Scholar
- 30.J. C. Grosskreutz, in “Corrosion Fatigue”, NACE-2 (1972) p. 201.Google Scholar
- 31.R. G. Gates and W. A. Wood, J. Inst. Metals 96 (1968) 242.Google Scholar
- 32.G. W. Stickley and J. O. Lyst, J. Mater. 1 (1966) 19.Google Scholar