Spring Steel：65Mn, ASTM1566,C60E4,CK67,1.1231
standard：GB/T 3077-1999
●Chemical composition：
C ：0.62～0.70
Si：0.17～0.37
Mn：0.90～1.20
S ：allow remains content≤0.035
P ：allow remains content≤0.035
Cr：allow remains content≤0.025
Ni：allow remains content≤0.030
Cu：allow remains content≤0.025

●mechanical properties：
tensile strength σb (MPa)：≥980(100)
yield strength σs (MPa)：≥785(85)
extensibility δ5 (％)：≥9
reduction of area ψ (％)：≥30
notched bar impact strength αkv (J/cm2)：≥98(10)
rigidity ：≤229HB