Spring steel plate is hot-rolled flat product for heavy leaf springs, suspension plates and spring blanks where a thick, tough section is needed. We supply it annealed or normalized, and cut it to blank.
What Is Spring Steel Plate?
Spring steel plate is hot-rolled from continuously cast slab and then annealed or normalized to give the ductility needed for hot-forming heavy leaf and parabolic springs. Thick plate is the starting point for springs that must absorb large, repeated loads without cracking.
We stock and cut the standard spring grades — 65Mn, 50CrV4 / 51CrV4, SUP9 and 9260 — and can supply sawn or flame-cut blanks to your leaf-spring drawing.
Spring Steel Grades Available as Plate
These spring grades are available as plate:
| Grade | Standard | Typical Use |
|---|---|---|
| 65Mn | GB/T 4357, GB/T 1222 | Light coil & flat springs, clips, washers |
| 50CrV4 / 51CrV4 | EN 10270-2 (1.8159) | Engine valve springs, heavy coils, warm service |
| 6150 | ASTM A229 / A401 | Valve & torsion springs (North America) |
| SUP9 / 55Cr3 | JIS G3521, EN 10089 | Heavy leaf and coil springs |
| 9260 | ASTM A229 | Large leaf, buffer and suspension springs |
Size Range and Tolerances
Plate is cut from 6 mm up to 80 mm thick. Thickness, width and length are confirmed per order and to the relevant standard:
| Thickness | Width | Length | Condition |
|---|---|---|---|
| 6 – 20 mm | ≤ 1500 mm | ≤ 6000 mm | Annealed / Normalized |
| 20 – 40 mm | ≤ 2000 mm | ≤ 6000 mm | Annealed / Normalized |
| 40 – 80 mm | ≤ 2000 mm | ≤ 6000 mm | Annealed / Normalized |
| Cut blanks | per drawing | per drawing | Sawn / flame-cut |
Surface Finish and Delivery Condition
Plate is typically supplied in these conditions:
As-rolled plate for further forging or forming.
Softened for hot-forming leaf springs and easy machining of blanks.
Refined grain for consistent strength after forming.
Surface-milled plate to remove decarburisation before blanking.
Standards We Supply To
| Standard | Scope |
|---|---|
| EN 10089 | Hot-rolled spring steel (plate and wide strip) |
| ASTM A689 | Carbon and alloy steel bars for springs |
| ASTM A29 | General carbon and alloy steel bars/plate |
| JIS G4801 | Spring steel (SUP grades) |
Physical Properties of Spring Steel
| Property | Typical Value |
|---|---|
| Density | 7.85 g/cm³ |
| Elastic modulus (E) | ~200 GPa |
| Shear modulus (G) | ~79 GPa |
| Thermal conductivity | ~45 W/m·K at room temperature |
| Coefficient of thermal expansion | ~12 ×10⁻₆ /K (20 – 200 °C) |
Applications of Spring Steel Plate
Truck, trailer and railway leaf-spring packs.
Parabolic and multi-leaf suspension members.
Thick plates for shock-absorbing springs.
Cut blanks for machined or formed springs.
Plate cut and then forged to shape.
Thick sections in vibrating equipment.
Quality Control and Mill Certificates
Every Plate order ships with an EN 10204 3.1 mill certificate covering heat chemical analysis and the mechanical and dimensional checks on record. We add, on request: ultrasonic or magnetic-particle inspection, hardness mapping, straightness and flatness checks, decarburisation or surface-depth checks, and third-party inspection (SGS / BV) at the mill or before loading. Dimensions are verified to the relevant EN / ASTM / JIS standard or your drawing.
Frequently Asked Questions
What is the thickest spring-steel plate you supply?
Up to 80 mm as rolled, and we cut blanks to drawing from thicker forged block on request.
Do you cut plate to leaf-spring blanks?
Yes — sawn or flame-cut to your drawing, with edge prep and hardness check.
Which grade for a heavy truck leaf spring?
SUP9 / 55Cr3 or 50CrV4 for high-load leaves; 65Mn for lighter duty.
Is the plate supplied annealed?
Yes, annealed or normalized as standard so it can be hot-formed and heat-treated after blanking.
Can you supply normalized plate?
Yes, normalized plate is available where a refined grain and uniform strength are required.
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