55Si2Mn Spring steel bar

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11-May-2024

55Si2Mn spring steel silicon and manganese improve flexibility strength and yield ratio, improved hardenability, temper resistance and resistance to relaxation stability, thermal sensitivity is also smaller, but decarbonization tend to be larger, especially silicon and carbon content when high, easy graphitization of carbon, the steel becomes brittle. 55Si2Mn spring steel used for cars, tractors and motorcycles on the damping spring and coil springs, cylinder valve springs, thermal springs are also used to use the following 250 ℃.

55Si2Mn spring steel chemical composition

C	Si	Mn	S	P	Cr	Ni	Cu
0.52～0.60	1.50～2.00	0.60～0.90	≤0.035	≤0.035	≤0.35	≤0.35	≤0.25

55Si2Mn mechanical properties of spring steel
Tensile strength σb (MPa): ≥ 1274 (130)
Yield strength σs (MPa): ≥ 1176 (120)
Elongation δ10 (%): ≥ 6
Reduction of ψ (%): ≥ 30
Hardness: hot, ≤ 302HB; Cold Drawn + heat treatment, ≤ 321HB

Heat treatment and microstructure specifications
Heat treatment specifications: quenching 870 ℃ ± 20 ℃, oil cooling; tempering 480 ℃ ± 50 ℃ (when special needs, ± 30 ℃).
Microstructure: Tempered troostite.

Delivery status
Hot-rolled steel to heat treatment or heat treatment delivery, cold-drawn steel to heat treatment delivery.