Material Name: Gear Steel SCM421

Executive Standard: JIS G4053-2003

1 Features and application:

SCM421 thermal processing performance is good, good cutting performance after normalizing, quenching and tempering after the good mechanical properties and low temperature impact toughness, after carburizing high flexural strength and wear resistance, but poor welding performance , appropriate warm-up before welding, after welding, tempering should be timely. SCM421 commonly used in the manufacturing requirements of high surface hardness, good wear resistance of carburized important parts such as gears, cam rod, pin, etc.

(2) Chemical Composition:

Carbon C: 0.17 ~ 0.23

Si Si: 1.15 ~ 1.35

Manganese Mn: 0.70 ~ 1.00

Sulfur S: to allow the residual content ≤ 0.030

Phosphorus P: to allow the residual content ≤ 0.030

Chromium Cr: 0.90 ~ 1.20

Ni: to allow the residual content of ≤ 0.25

Copper Cu: to allow the residual content ≤ 0.030

Mo Mo: 0.215 ~ 0.25

3 Mechanical properties:

Tensile strength σb (MPa): ≥ 1175 (120)

Yield strength σs (MPa): ≥ 885 (90)

Elongation δ5 (%): ≥ 10

Reduction of area ψ (%): ≥ 45

Impact energy Akv (J): ≥ 55

Impact toughness αkv (J/cm2): ≥ 69 (7)

Hardness: ≤ 217HB

Sample size: Sample size is 15mm rough

4 Heat treatment and microstructure specifications:

Standard heat treatment: quenching 850 ℃, oil cooling; tempering 200 ℃, water, air-cooled.

Microstructure: martensite.

5 Delivery status: to heat treatment (normalizing, annealing, or tempering) or heat treatment delivery, delivery status should be indicated in the contract.