Spring steel strip is cold-rolled flat product for flat springs, saw blades, clutch plates and shims. We supply it annealed or hardened-and-tempered, with controlled edge and flatness, to EN, ASTM and JIS specs.
What Is Spring Steel Strip?
Spring steel strip is produced by cold-rolling hardened flat bar to tight thickness and flatness, then supplied either soft-annealed for blanking and forming or hardened-and-tempered for directly assembled flat springs. Consistent thickness and a clean, decarburisation-free surface are what make the strip spring reliably.
We keep the full spring grade range available as strip — 65Mn for cost-sensitive clips, 50CrV4 / 6150 for high-cycle flat springs, and 9260 / SUP9 for heavier leaf and flat sections.
Spring Steel Grades Available as Strip
These spring grades are available from stock or to order as strip:
| 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
Strip is rolled from 0.1 mm shim stock up to 6 mm plate-strip. Thickness tolerance tightens for the thinner, critical grades:
| Thickness | Width | Thickness Tol. | Condition |
|---|---|---|---|
| 0.1 – 0.5 mm | ≤ 200 mm | ± 0.01 mm | Annealed / HT |
| 0.5 – 2.0 mm | ≤ 300 mm | ± 0.02 mm | HT / Annealed |
| 2.0 – 4.0 mm | ≤ 300 mm | ± 0.03 mm | HT / Annealed |
| 4.0 – 6.0 mm | ≤ 300 mm | ± 0.05 mm | Annealed / HT |
Surface Finish and Delivery Condition
Choose the delivery condition that matches your blanking and setting process:
Soft strip for blanking, bending and then heat-treating the finished spring.
Pre-hardened strip ready to be blanked and set — no further heat treatment needed.
High-strength strip for light flat springs and clips.
Lightly finished strip with a blue oxide for corrosion resistance and appearance.
Standards We Supply To
| Standard | Scope |
|---|---|
| EN 10132 | Heat-treated cold-rolled narrow strip (spring grades) |
| EN 10089 | Hot-rolled and cold-rolled spring steel |
| ASTM A684 | Cold-rolled spring steel strip |
| JIS G3311 | Cold-rolled special strip |
| 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 Strip
The classic strip use — flat springs in vehicles and machinery.
Hardened-and-tempered strip for bandsaw and blade stock.
Flat plates stamped from spring strip.
Thin, accurately sized strip for spacing.
Curved and wave washers blanked from strip.
Stable, flat strip for rules and scales.
Quality Control and Mill Certificates
Every Strip 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
Do you supply hardened-and-tempered spring strip?
Yes, in the common grades. Hardened-and-tempered strip is ready to blank and set, saving you a heat-treat step.
What thickness tolerance can you hold?
From ±0.01 mm on thin shim stock up to ±0.05 mm on thicker strip, per EN 10132 classes.
Can the strip be supplied with slit edges?
Yes — square or round slit edges, with deburred options for blanking tools.
Which grade should I pick for a high-cycle flat spring?
Chromium-vanadium 50CrV4 / 6150 gives the best fatigue life; 65Mn is the economical choice for lighter duty.
Is the surface decarburisation-free?
We control decarburisation on hardened-and-tempered strip and can add a depth check on request.
Related Products
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