Effect of Prefabricated Crack Arrest Line on Fatigue Crack Growth Behavior of Industrial Pure Iron DT4C

According to the ANSYS simulation, the size of the prefabricated "straight-circle" shaped crack arrest line on the fatigue crack growth path was determined. Standard extended compact tensile specimens were sampled from industrial pure iron DT4C, and then crack arrest lines were prefabricated at different distances from the root of the U-shaped notch (L_a was 6.4, 7.0, 7.6 mm, respectively). The effect of L_a on the fatigue crack growth behavior of specimens was studied by fatigue crack growth tests and fatigue fracture surface analysis. The results show that when L_a was 7.6 mm, the introduction of crack arrest line reduced the stress at the crack tip and prolonged the fatigue life of the specimen. Before the crack tip reached the arrest crack line position, the introduction of the crack arrest line at L_a of 6.4 mm improved the crack growth rate, while that at L_a of 7.6 mm reduced the crack growth rate. After the fatigue crack tip passed through the crack arrest line position, the crack growth rates of all the specimens with crack arrest line decreased significantly. The crack growth zone of specimens without and with crack arrest lines showed fatigue striation characteristics and the instantaneous fracture zone showed dimple fracture characteristics.