A comparison of fatigue crack growth of three alloy steels at elevated temperature
- Publication Type:
- Journal Article
- Theoretical and Applied Fracture Mechanics, 1989, 11 (1), pp. 9 - 19
- Issue Date:
Fatigue cracks were grown in alloy steels by the use of a triangular loading waveform with a frequency of 1 Hz and an R-ratio of 0.1, and the crack growth rates were determined. The steel alloys Fe-1%Cr-0.5%Mo and Fe-1.5%Mn-0.8%Ni-0.5%Mo (SA508) were tested at 450 ° C, and Fe-1%Cr-0.5%Mo and Fe-0.5%Cr-0.5%Mo-0.25%V at 550 ° C. Statistical treatment of the results indicated that, over the range of alternating stress intensities applied, the fatigue crack growth rates were very similar for each pair of alloys tested. The use of the Paris Law to describe the rates of fatigue crack growth would have led to an erroneous conclusion in this regard, and a sigmoidal descriptive model is therefore proposed for the growth of fatigue cracks. With the use of a microcomputer, this model is not much more difficult to apply than the Paris Law, and gives a far better description of the results. Finally, a statistical method for the comparison of sets of data on fatigue crack growth is presented and demonstrated. © 1989.
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