Abstract:

ESDU 93033 presents data that compare the behaviour of long and short cracks which are longer than the typical microstructural dimension but are not substantially larger than the radius of the plastic zone at the crack tip. Experimental data extracted from the literature for crack growth rate under constant amplitude loading are presented graphically against stress intensity factor range for both long and short cracks at various stress ratios in air for AISI 4340, HY 130, AISI 1045, SAE 0030 (UNS J 03010) and AISI 1020. In addition, there are data obtained in vacuum for E460, and in salt solution and sea water for HY 130. Data in air for E460, A508, QIN and 304 are for only one stress ratio (but include the effect of sea water for QIN). Data for AISI 316 are for short cracks only in air at two stress ratios and for EN5 are for short and long cracks in sea water and one stress ratio only. No consistent relationship between yield strength and either short or long crack growth behaviour was found, but where a short crack effect was evident the threshold value of stress intensity factor range was lower than for long cracks, and the crack growth rate at low values of stress intensity factor range was greater.