Why isn’t SUP8 spring steel in the JIS G4801 standard?
When JIS G 4801 was created in 1950, the standard materials were SUP1,2,3,4,5,6,7,8, but in the 1959 revision, SUP1,2,5,8 were deleted and SUP9, 10, 11 were added.
Unfortunately, we did not know why SUP8 was deleted because it is Si-Cr steel and it is not duplicated with other steel grades. Also, in the 1984 revision of JIS G 4801, SUP12 was added as Si-Cr steel, but this is not a to replace SUP8, and it seems to be a material equivalent to SAE9254 with a different Si level.
