55Si2Mn spring steel
 Introduction
 Material Name: 55Si2Mn

 Standard: GB / T 1222-1984
 ● Features and application:
 55Si2Mn silicon and manganese spring steel 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 and carbon content high, easily graphitized carbon, the steel brittle. 55Si2Mn spring steel used for cars, tractors and locomotive damping spring and coil springs, cylinder valve spring, can also be used with heat 250 ℃ the following spring.
 Chemical composition
 ● 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
 ● 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