65Mn Manganese improve hardenability, φ12mm the hardenability of steel oil can, a small surface decarburization tendency than silicon, the mechanical properties after heat treatment is better than carbon steel, but overheating sensitivity and temper brittleness. As small size of flat, round spring, spring seat, spring winding, spring ring can also be produced, valve springs, clutch springs, brake springs and cold drawn steel wire cold roll coil spring.

    Has excellent overall performance, such as mechanical properties (particularly elastic limit, ultimate strength, yield ratio), bullet-proof by performance (ie, decreased resistance to elastic properties, also known as anti-relaxation properties), fatigue properties, hardenability, physical and chemical properties (heat resistance, low temperature, oxidation, corrosion, etc.). In order to meet these performance requirements, spring steel with excellent metallurgical quality (high purity and uniformity), good surface quality (surface defects and decarburization strict control), the exact shape and size.

Chemical composition:

        Carbon C: 0.62 ~ 0.70


        Si Si: 0.17 ~ 0.37


Manganese Mn: 0.90 ~ 1.20


Sulfur S: ≤ 0.035


Phosphorus P: ≤ 0.035


Chromium Cr: ≤ 0.25


Ni-Ni: ≤ 0.30


Copper Cu: ≤ 0.25

Mechanical properties:

        Tensile strength σb (MPa): ≥ 980 (100)


Yield strength σs (MPa): ≥ 784 (80)


Elongation δ10 (%): ≥ 8


Reduction of area ψ (%): ≥ 30


Hardness: hot, ≤ 302HB; cold-drawn + heat treatment, ≤ 321HB