(Carburizing) bearing steel: SNCM420
● Features and Scope:
Is a commonly used alloy carburizing steel, has a very high surface hardness, wear resistance and contact fatigue strength after carburizing treatment, while heart Ministry also retain good toughness, can withstand high impact loads. Mainly used for railway bearings impact resistance, wear parts.
● Chemical Composition:
Carbon C: 0.17 ~ 0.23 (tolerance: ± 0.02)
Si Si: 0.15 ~ 0.40 (tolerance: ± 0.03)
Mn Mn: 0.40 ~ 0.70 (tolerance: ± 0.04)
Sulfur S: ≤0.030 (tolerance: +0.005)
Phosphorus P: ≤0.030 (tolerance: +0.005)
Chromium Cr: 0.35 ~ 0.65 (tolerance: ± 0.15)
Ni Ni: 1.60 ~ 2.00 (tolerance: ± 0.05)
Copper Cu: ≤0.30 (tolerance: +0.05)
Mo Mo: 0.20 ~ 0.30 (tolerance: ± 0.02)
● Mechanical Properties:
Tensile strength σb (MPa): ≥980 (100)
Elongation δ5 (%): ≥13
Reduction of ψ (%): ≥45
Impact toughness αkv (J / cm2): ≥78 (8)
Sample size: Sample size is 25mm
● Heat treatment and microstructure specifications:
Heat treatment specifications: quenching, the first 880 ± 20 ℃, the second 800 ± 20 ℃, oil cooling; tempering, 150 ~ 200 ℃, air cooling.
Microstructure: carburizing layer of high carbon martensite. Core part of a low-carbon martensite.
● Delivery status: hot-rolled or forged steel hot-rolled (forged) state or annealed state delivery. Cold-drawn steel in annealed condition delivery.