spring steel SUP9

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SKU: Case Hardening steel-2-1 Category: Tags: , ,


SUP9 | Spring Steel | 55CrMnA | 55Cr3 | 1.7176 | 527A60 | 55C3 | ASTM 5155

What is SUP9 steel?

JIS SUP9 Steel is a high quality Cold work Spring Steel, It belong to the high quality high carbon alloy Spring Steel. Oil Quenched & Tempered Hardness is 28-34 HRc. SUP9 steel Annealing delivery hardeness less than 250HB.


sup9 Chemical composition

C(%) 0.52-0.60 Si(%) 0.15-0.35 Mn(%) 0.65-0.95 P(%) ≤0.030
S(%) ≤0.035  Cr(%) 0.65-0.95

55Cr3 Equivalent alloy Spring Steel

USA Germany China Japan France England Italy Poland ISO Austria Sweden Spain
5155 / G51550 55Cr3 / 1.7176 55CrMnA SUP9 55C3 ≈527A60 55Cr3

sup9 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.

 sup9 Mechanical Properties

The mechanical properties of SUP9 Spring Steels are outlined in the following table.

Tensile strength Conditions to yield strength Elongation Reduction of area Hardness (Hot Rolled) Hardness (Cold Drawn)
σb (MPa):≥1225(125) σ0.2 (MPa):≥1080(110) δ5 (%):≥9 ψ (%):≥20 ≤321HB;


SUP9 steels, Highlight the advantage is good hardenability, another hot working performance, comprehensive mechanical properties, Decarburization resistance is also good big cross section of various important spring, such as automobile, locomotive, large plate spring, spring, etc. SUP9 Spring main used for heavy vehicles, tractors, industrial production load, stress and the diameter of the larger plate spring and helical spring