SUJ2鋼の超長疲労寿命挙動(機械工学科,工学部創設40周年記念号)

Abstract

In order to investigate the very long fatigue life characteristics, the rotating bending fatigue tests were carried out on the high strength steel SUJ2 material. The main results summarized in this study are as follows: (1) The test pieces have shown the S-N curve of the typical two-stage folding shape. (2) It is found out that the origin of fracture is the slip or grinding flaw type on the surface in the test pieces when they fracture in the range of the low cycles. It is also found out that the origin of fracture is the inclusion (Fish-eye type) inside of the test pieces when they fracture in the range of the high cycles. (3) Because the test pieces fracture even after they have exceeded the number of cycles of 107, establishment of the design method for very long life is important.