C67S Steel Strip: A High-Carbon Spring Steel for Precision Applications

1. Material Overview

The C67S steel strip is a high-carbon spring steel strip renowned for its exceptional elasticity, wear resistance, and fatigue resistance. Its nomenclature follows international material coding standards:

C: Denotes Carbon Steel.

67: Indicates an average carbon content of ~0.67% (high-carbon composition).

S: Typically signifies Spring applications or special processing techniques.

Precision-rolled and heat-treated, C67S is widely used in precision machinery, tool manufacturing, and high-load elastic components.

2. Key Properties

High Strength & Elasticity

Carbon content: 0.65%–0.75%.

After quenching + medium-temperature tempering, tensile strength reaches 1,600–1,900 MPa, with a high elastic limit, ideal for repeated deformation.

Wear & Fatigue Resistance

Uniform microstructure (primarily tempered troostite) enhances durability under cyclic stress, outperforming standard carbon steels.

Machinability

Annealed state: Moderate hardness (HB 200–250) for easy stamping or coiling.

Hardened state: High rigidity (HRC 45–52) for demanding applications.

Surface Quality

Cold-rolled surface finish (Ra ≤ 0.8 μm); optional coatings (zinc, phosphating, or oiling) improve corrosion resistance.

3. Typical Applications

Precision Springs: Watch mainsprings, valve springs, relay contacts.

Cutting Tools: Saw blades, industrial knives, tool substrates.

Mechanical Components: Shims, clutch plates, high-stress pins.

Automotive: Suspension leaf springs, seatbelt retractor parts.

4. Processing & Usage Guidelines

Pre-Forming Annealing: Soften at 680–720°C for complex shaping.

Heat Treatment: Optimize toughness/strength balance via oil quenching (830–860°C) + 400°C tempering.

Corrosion Protection: Use coated variants or regular oiling in humid environments.

5. Critical Notes

Welding: Poor weldability; specialized methods (e.g., brazing) required.

Cold Bending: Avoid excessive deformation to prevent microcracks; multi-step forming recommended.

Storage: Moisture-proof packaging essential to prevent oxidation.