GROWTH BEHAVIOUR OF SMALL FATIGUE CRACK AND FATIGUE-LIFE PREDICTION FOR HIGH-STRENGTH STEEL 30CrMnSiNi2A
30CrMnSiNi2A高强钢的疲劳小裂纹扩展特性及寿命预测

Single-edge-notched tension (SENT) specimens under constant load amplitude were used to obtain the small crack growth information via an acetate replica method. The observed results show that more cracks are surface ones and initiated at inclusion-particles or voids on the surface of the notch. Steel 30CrMnSiNi2A does not exhibit a significant short crack effect when stress ratio R=0. But a slight small crack effect was observed at R=-1, and the short cracks can grow below the long crack threshold. Using the closure crack growth model and a microstructural defect as an initial crack, the small crack growth rate and the total fatigue life can be predicted and the predicted results are in reasonable agreement with experiments.