This is my first time posting here.
I am in trouble with the fatigue limit stated in spring design.
It seems that there is the same question here before, but can you show me the S-N diagram of the piano wires (SWPA, SWPB) and SWOSC-V?
Could you also provide the material limit diagram?
Thank you for writing to us, MIZU!
Unfortunately, there is no S-N curve data for SWOSC-V… <(_ _)>.
Regarding the allowable stress, please refer to this link for your information!
Hello, I have a question for you.
Could you please tell me about the fatigue strength of SWP-B (piano wire) and SWOSC-V (oil tempered wire).
Looking at JISB2704 and various materials, it is possible to calculate the fatigue strength from the tensile strength. If the materials have the same tensile strength, the fatigue strength can be calculated.
Therefore, according to JIS, since SWP-B and SWOSC-B have the same tensile strength, I presume their fatigue strength to be the same. On the other hand, SWOCS-V is said to be a material with excellent fatigue resistance, and because it is “oil-tempered”, and is subjected to heat treatment, I think it is correct to think that it is a material superior in material strength, but what should we say about the fatigue strength of both materials?
Spring Newbie, thank you for your question!
SWOSC-B and SWOSC-V are listed in JIS standard with the following steel types.
Oil tempered wire for spring (SWOSC-B)
Oil tempered wire for valve spring (SWOSC-V)
As for fatigue strength, SWOSC-V that is manufactured for valve springs of internal combustion engines is superior.
The difference here is that the control level for impurities and defects is high.
In terms of chemical composition, the content of “P” and “S” is low, and the depth of defects and decarburized layer are strictly controlled.
Therefore, since there are few material defects that affect fatigue strength, the probability of breakage is lower than that of SWOSC-B, and when fatigue tests are performed at the same level stress amplitude, it can be said that SC-V has better fatigue strength.
