SUP9 Sping Steel Wire


SUP9 is a grade of spring steel, which has higher strength, ductility and toughness, better hardenability, lower overheating sensitivity than manganese steel, decarburization tendency smaller than silicon manganese steel, large temper brittleness. For vehicles, tractors industrial heavy load, stress larger leaf springs and larger diameter coil springs.


Chemical Composition:


 CSi Mn Cr Ni Cu
 0.52~0.60 0.65~0.950.17~0.37  ≤0.0300.030 0.65~0.95  ≤0.35 ≤0.25 0.10~0.20



Mechanical properties:


 Tensile Strength σb (MPa): Yield Strength σ0.2 (MPa): Elongation δ5 (%):Section shrinkage ψ (%):  Hardness: 
≥ 1225 (125)  ≥1080 (110)≥ 9 ≥20 

Hot rolled: ≤ 321HB;

Cold pull + heat treatment: ≤ 321 HB


 Equivalent Grade:


 G5155055CrMnA  55Cr3  525A58 55Cr3


Heat treatment Related

  • Annealing of SUP9 Spring Steel

Slowly heated to 740-770 ℃ and allow enough times, let the steel to be thoroughly heated, Then cool slowly in the furnace. The SUP9 tool  steel will get MAX 250 HB (Brinell hardness).


  • Hardening of SUP9 Spring Steel

SUP9 steels should be heated uniformly to 830-860°C (1526-1580°F) until completely heated through. About 30 min per 25 mm of ruling section is to be provided and then the steels should be immediately quenched in oil.


  • Tempering of SUP9 Spring Steel

Tempering of SUP9 steels is performed at 460-510°C, Soak well at the selected temperature and soak for at least one hour per 25mm of total thickness.


Related Spring Steel Materials