Introduction
Spring steel 55Si2MnB
● Features and application: silicon and manganese to improve strength and yield ratio flexibility, improve hardenability, tempering stability and resistance to anti-relaxation stability, thermal sensitivity is also small, but decarburization tend to be larger, especially silicon with higher carbon content, carbon graphite easy to make steel brittle. For cars, tractors and locomotive damping spring and coil springs, cylinder valve spring, can also be used with heat 250 ℃ the following spring. [1]
Chemical composition
Carbon C: 0.52 ~ 0.60
Si Si: 1.50 ~ 2.00
Manganese Mn: 0.60 ~ 0.90
Sulfur S: ≤ 0.035
Phosphorus P: ≤ 0.035
Chromium Cr: ≤ 0.35
Ni-Ni: ≤ 0.35
Copper Cu: ≤ 0.25
Mechanical properties
Tensile strength σb (MPa): ≥ 1274 (130)
Yield strength σs (MPa): ≥ 1176 (120)
Elongation δ10 (%): ≥ 6
Reduction of area ψ (%): ≥ 30
Hardness: hot, ≤ 302HB; cold-drawn + heat treatment, ≤ 321HB [3]
