Could you help me answer this question?
Currently, we conducted a durability test for disc springs made of SK5M, but when we applied dynamic load more than 1.2 million times, one of the 6 samples broke before it reached 1.2 million times. The fracture surface was in the form of fatigue fracture, but since only one of the six samples occurred, it has not been possible for us to investigate whether the cause was the strength of the springs or the influence of other factors. I have assumed the fatigue limit was the cause, but would you please tell me if there are any documents that describe the number of times that springs can be used and the stress limit?
Regarding the fatigue diagram, there are characteristics of the repetition described in JIS B2706 (for disc springs). They are also described in the technical information on our website too. However, those are the characteristics in the case of SUP10 material. In the case of SK5M, it is stated in the explanation of JIS B 2706 that the fatigue limit should be 80% of the values in the figure. How about evaluating it as 80% of the fatigue values of SUP10?
