Carbon Steel Spring Strip
High-carbon steel spring strip delivers the high yield strength, fatigue resistance, and elastic modulus required for springs, clamps, washers, saw blades, and precision flat components. By controlling carbon content in the 0.60–0.75 % range and applying cold rolling followed by quenching and tempering, spring strip achieves hardness levels of 42–52 HRC while retaining sufficient ductility for forming and coiling operations. Huaxia-Steel supplies 65Mn, 1075, C75S, and CK75 spring strip in thicknesses from 0.1 mm to 6.0 mm with EN 10204 3.1 certification.
Product Specifications
| Parameter | Specification |
|---|---|
| Thickness | 0.1 mm – 6.0 mm |
| Width | 5 mm – 400 mm (slit edge); up to 600 mm (mill edge) |
| Coil inside diameter | 300 mm, 400 mm, 508 mm (standard); custom ID available |
| Coil outside diameter | Up to 1,200 mm |
| Coil weight | 500 kg – 3,000 kg |
| Thickness tolerance | ±0.01 mm (≤ 1.0 mm), ±0.015 mm (1.0 – 3.0 mm), ±0.02 mm (> 3.0 mm) |
| Width tolerance | ±0.10 mm (slit edge), +2 / –0 mm (mill edge) |
| Camber | ≤ 2 mm per 1,000 mm |
| Surface finish | Bright polished, blue polished, matte, or oiled |
| Edge condition | Slit edge, deburred edge, or rounded edge |
Available Grades and Standards
| Standard | Grade | C (%) | Mn (%) | Hardness (HV) | Tensile (MPa) |
|---|---|---|---|---|---|
| GB/T 1222 | 65Mn | 0.62 – 0.70 | 0.90 – 1.20 | 430 – 520 | 1,400 – 1,800 |
| ASTM A684 | 1075 | 0.70 – 0.80 | 0.40 – 0.70 | 450 – 550 | 1,500 – 1,900 |
| DIN 17222 | C75S (1.1248) | 0.70 – 0.80 | 0.60 – 0.90 | 450 – 550 | 1,500 – 1,900 |
| EN 10132-4 | C75S | 0.70 – 0.80 | 0.60 – 0.90 | 450 – 550 | 1,500 – 1,900 |
| JIS G4801 | SUP6 | 0.55 – 0.65 | 0.70 – 1.00 | 400 – 480 | 1,300 – 1,700 |
| JIS G4801 | SUP9 | 0.50 – 0.60 | 0.65 – 0.95 | 400 – 480 | 1,300 – 1,700 |
Manufacturing Process
- Hot rolling: Continuous casting slab is hot-rolled to intermediate strip thickness (2.5 – 8.0 mm) with tight control of finishing temperature to optimize pearlite lamellar spacing.
- Pickling: Hot-rolled strip is acid-pickled to remove oxide scale, preparing the surface for cold rolling.
- Cold rolling: Multi-stand tandem cold mills reduce thickness to final gauge with total reduction ratios of 50–85 %. Cold work increases strength and hardness.
- Annealing (intermediate or final): Spheroidizing annealing produces a soft, formable condition (≤ 220 HV) for severe forming operations. Bright annealing in a hydrogen-nitrogen atmosphere yields a polished surface.
- Quenching and tempering: Austenitizing at 800 – 840 °C, rapid quenching in oil or polymer, followed by tempering at 350 – 450 °C achieves the final spring hardness of 42 – 52 HRC.
- Slitting and edge dressing: Master coils are slit to final width with precision slitting lines. Edges can be deburred or rounded to prevent stress concentrations in service.
Applications
- Leaf springs and parabolic springs: For trucks, trailers, and railway wagons. Multi-leaf packs are assembled from strips of graduated length.
- Coil springs and spiral springs: Clock springs, power springs, and torsion springs for automotive seat recliners, garage doors, and industrial equipment.
- Clips, clamps, and fasteners: Spring steel clamps for pipes, hoses, and cable management; retaining rings and circlips.
- Saw blades and cutting tools: Band saw blades, reciprocating saw blades, and knife blades requiring high hardness and wear resistance.
- Shims and washers: Belleville washers, wave washers, and precision shims for preload and tolerance compensation.
- Electrical contacts and relays: Thin spring strip forms the contact fingers and armatures in switches and circuit breakers.
Quality Assurance
- EN 10204 3.1 mill test certificate with full chemical analysis and mechanical test results.
- Hardness testing on every coil: Rockwell C (HRC) or Vickers (HV) according to customer specification.
- Surface inspection: visual check for scratches, roll marks, pits, and decarburization.
- Microstructure examination: verification of tempered martensite with no ferrite networks or excessive retained austenite.
- Decarburization depth measurement: maximum 3 % of nominal thickness per DIN 17222.
- Flatness and camber measurement on every slit coil.
- Optional: fatigue testing, corrosion testing, and coating adhesion tests.
Packaging and Shipping
- Coils are wrapped in oiled paper and VCI film to prevent rust during storage and transit.
- Wooden pallets or steel saddles support coils during handling.
- Eye-to-sky or eye-to-wall orientation in containers depending on coil dimensions and container type.
- Shipping documentation includes packing list, mill test certificate, and certificate of origin.
- Custom labeling with customer part numbers, batch codes, and barcodes available upon request.
Request a quotation for carbon steel spring strip. Provide thickness, width, grade, hardness requirement, edge condition, surface finish, and coil weight preference. Huaxia-Steel offers precision slitting, edge rounding, and cut-to-length blanking services. Contact us for technical support and pricing.
