5120
Data verified5120 is a chromium case-hardening steel for small gears and wear parts. With about 0.8% chromium it forms a hard carburized case over a tougher core than plain carbon carburizing grades give.
Chemical composition
| Element | Content (%) |
|---|---|
| C | 0.17–0.22 |
| Si | 0.15–0.35 |
| Mn | 0.70–0.90 |
| P | ≤0.035 |
| S | ≤0.040 |
| Cr | 0.70–0.90 |
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 | 600–850 MPa (typ.) |
| Density | 7.85 g/cm³ |
Heat treatment
Carburize 900–930 °C; quench 800–830 °C oil; temper 150–200 °C.
Equivalent grades
| Standard | Designation |
|---|---|
| din | 1.7027 (20Cr4, near) |
| aisi | 5120 |
| jis | SCr420 |
| gb | 20Cr |
Compare side by side: 5120 vs 20MnCr5 · 5120 vs 8615
Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.
Applications & Processing
Applications: Small gears, pinions, bushings, cam parts, wear pins.
Processing: Machines well before carburizing; finish-grind after hardening.
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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.