FATIGUE CRACK GROWTH ANISOTROPY IN KX 70 HSLA STEEL
Abstract
Fatigue crack growth (FCG) measurements were performed at ambient temperature and liquid nitrogen temperature on KX 70-HSLA steel in two directions perpendicular to the direction of rolling. It was found, that the FCG rate, at of the same ?K value is approximately from three to four times slower at 77 K than at 295 K. Experimental results obtained in this study, confirmed the possibility of determination of different FCG behavior of materials in dependence on the testing method used. It was also shown that, the marked FCG rate anisotropy determined from conventional long-crack growth tests, was not observed in the case of initiation of cracks in sharp-notch specimen and of FCG at gradual step-wise increase of loading. The reasons for this difference are discussed in terms with fracture surface roughness behind the fatigue crack tip. Such results provide further confirmation that the FCG rate anisotropy can be controlled primarly by crack closure effect.
Editors and press
AMS online
