4118
Data verified4118 is a low carbon Cr-Mo carburizing steel, the economy case-hardening grade of the 41xx family. Its small molybdenum addition gives a stronger, tougher core than plain chromium case steels such as 5120.
Chemical composition
| Element | Content (%) |
|---|---|
| C | 0.18–0.23 |
| Si | 0.15–0.35 |
| Mn | 0.70–0.90 |
| P | ≤0.035 |
| S | ≤0.040 |
| Cr | 0.40–0.60 |
| Mo | 0.08–0.15 |
Weight percent, per the governing standard ranges. Actual values per heat are on the mill certificate.
Properties
| Case hardness (carburized) | 58–62 HRC |
| Core tensile strength | 650–900 MPa (typ.) |
| Density | 7.85 g/cm³ |
Heat treatment
Carburize 900–930 °C; quench 820–850 °C oil; temper 150–200 °C.
Equivalent grades
| Standard | Designation |
|---|---|
| din | 20CrMo4 type (near) |
| aisi | 4118 |
| jis | SCM418 |
| gb | 20CrMo |
Compare side by side: 4118 vs 8620 · 4118 vs 5120
Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.
Applications & Processing
Applications: Gears, pinions, chain pins, bushings, camshafts (light).
Processing: Excellent machinability before carburizing; standard case-hardening practice.
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Ask for a quotationVisit NasteelSource: SAE J404 published ranges · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.