Please tell me the hardness of the finished products of SWP-A and SWP-B before and after heat treatment (temper: low-temperature annealing). Material diameter: φ1.2
Spring Newbie, thank you for your post!
We can not know the hardness of the piano wire until it is measured, but the tensile strength is listed below as a reference for its mechanical properties!!!
Material diameter: φ1.0 SWP-B, with low-temperature annealing: Approximately 2200MPa.
The tensile strength of the material without low-temperature annealing cannot be answered clearly because the number of data is small, but according to our experience, compared to materials with low-temperature annealing applied, the tensile strength decreases by about 1 to 2%.
* The above values may vary depending on the material manufacturer and production lot, so they are for reference only.
For highly accurate data, we recommend that you check the tendency by the tensile test and hardness measurement of the material each time!
Recently we face a problem. We bought a spring which are made of SWP-B, being split off along the drawing direction after fatigue. I measured its hardness, which can reach to 680HV!! I just wonder that will such high hardness bring up with brittleness due to low toughness ? The hardness of as-wire is around 570HV. Does it possible over- cold forming?
Dear Mr. Kelvin,
Thank you for your question!
Because we do not know the shape of the spring, in theory, if the hardness is HV680, it means that the tensile strength is approximately σB = 2350N/mm^2, which is not an unimaginable thing, especially with SWP-B material with a wire diameter of φ1.4 or less.
At this point, it is possible that the spring broke not because of fatigue failure, so it would be much appreciated if you could send us the dimensions and more details about the springs (shape, usage environment, usage conditions such as deflection, stroke…) so that we can help estimate the lifespan of the spring.
