2020 年 58 巻 5 号 p. 263-271
Recently, a technique has been developed to render harmless surface cracks which reduce the fatigue limit of metals by 20~60% by the effects of compres-sive residual stress induced by shot peening. This technique is called as sur-face crack non-damaging technology. For the purpose of contributing to reliability improvement of high strength steel equipment by surface crack non-damaging technology, the following research was carried out:
(a) The effects of aspect ratio of surface crack on maximum harmless crack depth (ahlm) of a high strength was calculated for three residual stress distributions.
(b) Assuming the value of safety factor, the relationship between the maximum allowable crack depth (acrN) and ahlm was investigated.
(c) The relationship between maximum detectable crack depth by non-destructive inspection (aNDI) and ahlm was compared, assuming that nondestructive inspection could detect the crack with sufficient probability.
(d) The relationship between ahlm, aNDI and ahlm were compared.