1988 Volume 6 Issue 4 Pages 543-550
The present report is intended to evaluate the difference of initial fatigue crack propagation rate between mild steel and high tensile strength steel in notch field subjected to high stress.
Two used materials (SS41, HT80) have similar characteristics in long crack propagation (R=-1) when small scale yield condition is satisfied. However, in low cycle (high stress) region (R=-1), initial fatigue crack propagation rate in center notched strip of SS41 is higher than that of HT80. This characteristics might result from elasto-plastic effect on fatigue crack propagation. By application of ΔJ calculated in this study, the asto-plastic effect could be evaluated.
As the results, it would be mentioned that initial fatigue crack propagation rate in notch field behaving elasto-plastically can be estimated from master curve of long crack by ΔJ considering cyclic yield strength of materials.