24 July 2021 Gear Steel Bar
SCM421 Gear Steel Bar
SCM421 is a gear steel specified in the Japanese standard JIS G4053-2003. It has good hot workability and good cutting performance after normalizing. It has good comprehensive mechanical properties and low temperature impact toughness after quenching and tempering. After carburized it has higher bending strength and wear resistance, but the welding performance will become lower, it should be preheated properly before welding and tempered in time after welding.
SCM421 is often used to manufacture important carburized parts that require high surface hardness and good wear resistance, such as gears, camshaft connecting rods, pins, etc.
Chemical Composition:
| C | Si | Mn | S | P | Cr | Ni | Cu | Mo |
|---|---|---|---|---|---|---|---|---|
| 0.17~0.23 | 1.15~1.35 | 0.70~1.00 | ≤0.030 | ≤0.030 | 0.90~1.20 | ≤0.25 | ≤0.030 | 0.215~0.25 |
Mechanical Properties:
| Tensile Strength σb (MPa) : | Yield Strength σs (MPa): | Elongation δ5 (%): | Reduction of Area ψ (%): | Impact Energy Akv (J): | Impact Toughness Value αkv (J/cm²): | Hardness | Sample Size |
|---|---|---|---|---|---|---|---|
| ≥1175(120) | ≥885(90) | ≥10 | ≥45 | ≥55 | ≥69(7) | ≤217HB | 15mm |
Heat treatment specification and metallographic structure:
Heat treatment specification: quenching at 850℃, oil cooling; tempering at 200℃, water cooling, air cooling.
Metallographic structure: tempered martensite.
Delivery status:
Delivery in the heat treatment (normalizing, annealing or high temperature tempering) or non-heat treatment status, the delivery status should be indicated in the contract.