When it comes to automotive manufacturing, material selection is critical for ensuring both safety and performance. Two commonly used alloy steels are SCM435 and 35CrMo. Both belong to chromium-molybdenum alloy steel families, yet their properties and applications differ, especially in precision automotive components like door lock catches, drive shafts, and transmission gears.
1. Chemical Composition
The composition of alloying elements directly determines performance differences between SCM435 and 35CrMo.
| Element | SCM435 (wt%) | 35CrMo (wt%) |
|---|---|---|
| C | 0.33–0.38 | 0.32–0.40 |
| Si | 0.15–0.35 | 0.17–0.37 |
| Mn | 0.60–0.90 | 0.40–0.70 |
| Cr | 0.90–1.20 | 0.80–1.10 |
| Mo | 0.15–0.30 | 0.15–0.25 |
| P & S | ≤0.025 | ≤0.030 |
Observation: SCM435 has slightly stricter impurity control (P & S), making it favorable for high-precision automotive parts.
2. Mechanical Properties
| Property | SCM435 | 35CrMo |
|---|---|---|
| Tensile Strength | 930–1080 MPa | 930–1080 MPa |
| Yield Strength | ≥785 MPa | ≥785 MPa |
| Elongation | ≥12% | ≥12% |
| Impact Toughness | Higher stability | High but less stable |
| Hardness (after Q&T) | 28–32 HRC | 28–34 HRC |
Observation: Both steels provide high strength, but SCM435 is more stable in impact performance, while 35CrMo can achieve slightly higher hardness after quenching and tempering.
3. Processing Performance
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SCM435
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Excellent machinability and uniformity.
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Better fatigue resistance, suitable for continuous cyclic load parts.
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35CrMo
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Stronger toughness and bending resistance.
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Ideal for heavy-duty parts requiring shock resistance.
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4. Typical Automotive Applications
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SCM435:
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Transmission gears
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Engine connecting rods
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Precision automotive bolts
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35CrMo:
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Door lock catches
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Drive shafts
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Suspension system components
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5. Summary
Both SCM435 and 35CrMo are excellent alloy steels, but the selection depends on application requirements.
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Choose SCM435 if you need precision, fatigue resistance, and stability.
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Choose 35CrMo if you need toughness, impact resistance, and bending strength.
In the automotive industry, manufacturers often use SCM435 for precision internal engine parts and 35CrMo for safety-critical structural parts like door lock catches, where high impact and fatigue resistance are crucial.
