1999 年 1999 巻 44 号 p. 25-29
Stainless steel strip is widely used for flat spring which requires corrosion resistance. SUS301 steel is especially used for the material of a spring as it is given high strength by cold rolling. However, scattering of the angle of bent product due to the large springback of the material appears to be a problem in a certain production. In this study, the effect of slight differences in thickness and hardness on the amount of springback in two lots of SUS301 is investigated. The material specification of each is within the tolerance of JIS G 4313, however, the lots are from different steel makers. L-shape bending test which is similar to a multiforming mechanism is adopted in this investigation. Results obtained show that the springback angle decreases with the increment of thickness and the decrement of hardness, but the change itself is very small within the same material lot. In addition, the relationship between the springback angle and the hardness does not apply through the different material lots, and it even appears to have a reversed tendency. Therefore, hardness is not appropreate to estimate the springback. Within the present experiment, the springback angle correlates with the stress corresponding to the strain at the surface of bent strip regardless of the difference in not only material lots but also bending direction against rolling direction.