SNCm420 - Alloy steel - Shanghai Zhilian steel trade

The main elements of a steel alloy of silicon, manganese, chromium, nickel, molybdenum, tungsten, vanadium, titanium, niobium, zirconium, cobalt, aluminum, copper, boron and rare earth. Including vanadium, titanium, niobium, zirconium and steel is strong carbide forming elements, as long as there is enough carbon, under appropriate conditions, can form their own carbides, when the lack of carbon or high temperature conditions, Atomically state into the solid solution; manganese, chromium, tungsten, molybdenum carbide forming elements, part of the atomic state into the solid solution, the other part of the formation of replacement-type alloy cementite; aluminum, copper, nickel, cobalt, silicon is not formed carbide elements, atoms generally present in solid solution in the state.
Many different types of steel, usually divided by the number of elements in low alloy steel (content <5%), in alloy steel (content of 5% to 10%), high alloy steel (> 10%); according to quality into high-quality alloy steel, alloy characteristics ● implementation of standards
China: GB / T 3203-1982
Japan: JIS G4053-2003
U.S. ASTM A534-2004
(Cementite) bearing steel: SNCM420
● Features and application: It is a commonly used alloy, carburization treatment has a high surface hardness, wear resistance and contact fatigue strength, while the Department has retained a good heart toughness that can withstand high impact loads. Mainly for railway bearings impact resistant, wear parts. ● Chemical Composition:
Carbon C: 0.17 ~ 0.23 (tolerance: ± 0.02)
Si Si: 0.15 ~ 0.40 (tolerance: ± 0.03)
Manganese 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 area ψ (%): ≥ 45
Impact toughness αkv (J/cm2): ≥ 78 (8)
Sample Size: Sample size is 25mm
● Heat treatment and microstructure specifications:
Standard heat treatment: quenching, the first 880 ± 20 ℃, the second 800 ± 20 ℃, oil cooling; tempering, 150 ~ 200 ℃, air-cooled.
Microstructure: carburized layer of high carbon martensite. Department for low-carbon martensite heart.
● Delivery status: hot-rolled or forged steel with hot-rolled (forged) state or annealed state delivery. Cold-drawn steel in the annealed condition delivered.