2018 年 84 巻 864 号 p. 18-00206
To quantitatively investigate the cause of the changes in arithmetic mean roughness Ra of austenitic stainless steel under low-cycle fatigue loading, precise observation focusing on slip bands was conducted on SUS316NG. During the loading, the specimen's surface topography was regularly measured using a laser microscope. The topography was then characterized by frequency analysis to identify the surface reliefs due to persistent slip bands (PSBs), and their heights were measured. The heights increased with the usage factor (UF). The amount of the increase with respect to UF increased with the strain range. These tendencies are similar to those for Ra. A comparison between Ra and the heights of surface reliefs caused by PSBs showed that the values were strongly correlated. The number of PSBs formed on the surface was estimated from the area ratio of PSBs. The area ratio increased with UF, which is similar to the relationship for Ra. A comparison between Ra and the area ratio showed that these values were also strongly correlated. The product of the height due to PSBs and the area ratio was calculated and it was compared with Ra. As a result, the product was in good agreement with Ra. Consequently, the surface texture parameter Ra represent both the change in the height and the number of surface reliefs due to PSBs.
