ive heard that coil springs are mostly 9260, and leaf springs 5160. I have no proof, but i was told this by a blacksmith with WAY more experience than I. Since im still green, i would take every thing i have to say with a grain of salt.
9260 is a Silicon, Manganese steel
the only other experience i have with this steel is the katana i own from maru katana
nothing else to compare it to thou as its the only sword i own.
ps. Grain of salt : )