ステンレス鋼板の複数亀裂がクリープ亀裂進展する場合の合体挙動

抄録

In order to investigate the coalescence behavior of multiple cracks due to creep crack propagation, a creep crack growth test was conducted under a high temperature environment of 600 °C using a specimen with two cracks, and the crack propagation behavior was investigated. The shape of the specimen was a flat plate, and two cracks were introduced by wire electric discharge machining, and fatigue cracks were propagated from the tips. The distance between cracks was expressed by the horizontal distance between the crack tips and the vertical distance between the two crack faces. It was found that the cracks may or may not coalesce depending on the position of the cracks, but the boundaries are not clear at this time. Observation of the fracture surface after the test revealed that the shape of the fatigue crack was curved, and the crack near the center of the cross section progressed more than the surface of the specimen. However, the width of the crack growth part due to creep was the same in the central part and the surface part. In addition, macroscopically, the crack propagated due to creep in the part where the crack propagated obliquely, but microscopically, the fracture surface transitioned from intergranular fracture to plastic collapse.