China SUP9 Spring Steel Sheet Supplier for High-Fatigue Spring Applications

For spring parts that take constant impact and cyclic loads day in and day out, resisting fatigue matters far more than just hard surface hardness. SUP9 spring steel sheet is a chromium-manganese spring alloy, engineered specifically for parts that need steady elasticity, solid wear resistance and a long working lifespan once heat treated. Most manufacturers pick this grade for automotive suspension pieces, farm machinery components and general industrial springs, all of which have to stand up to non-stop repeated stress out in the field.

Product Specifications

Item	Details
Product Name	SUP9 Spring Steel Sheet
Standard	JIS G4801
Grade	SUP9
Thickness	2.0–100 mm
Width	600–2500 mm
Length	2000–12000 mm or Custom
Supply Condition	Hot Rolled, Annealed, Normalized
Surface Finish	Black, Pickled
Processing Service	Cutting, CNC Machining, Heat Treatment
Payment Terms	T/T, L/C
Trade Terms	FOB, CFR, CIF

Item	Value
Carbon (C)	0.52–0.60%
Silicon (Si)	0.15–0.35%
Manganese (Mn)	0.65–0.95%
Chromium (Cr)	0.65–0.95%
Phosphorus (P)	≤0.030%
Sulfur (S)	≤0.030%
Tensile Strength	1270–1570 MPa
Hardness	42–50 HRC

Product Features

High Fatigue Resistance & Minimal Residual Deformation

With strictly controlled thin decarburization layer, SUP9 sustains 10⁷ times cyclic impact without obvious permanent deformation. It cuts fatigue fracture risk for heavy-load suspension springs and reduces your finished product after-sales maintenance expense.

Stable & Uniform Heat Treatment Response

Chromium alloy delivers excellent hardenability, ensuring consistent hardness across full plate thickness after quenching-tempering. Narrow batch hardness fluctuation avoids unstable spring stiffness in mass heat treatment, lowering your production reject rate.

High Wear Resistance for Long Service Life

Tempered hardness reaches 45–52 HRC, resisting abrasion on dynamic moving parts. Extend the service lifespan of truck, mining and agricultural machinery elastic components, supporting longer product warranty for your end customers.

Cost-Effective Machining Before Heat Treatment

Annealed delivery state (≤250HB) ensures smooth stamping, laser cutting and blanking. Less burr, fewer cracking defects and lower scrap rate to save your machining labor & raw material costs.