4820
Data verified4820 is the higher-carbon companion of 4815 in the 3.5% nickel carburizing family, giving a stronger core at the same case performance. It is used for large, heavily loaded gears in mining and aerospace service.
Chemical composition
| Element | Content (%) |
|---|---|
| C | 0.18–0.23 |
| Si | 0.15–0.35 |
| Mn | 0.50–0.70 |
| P | ≤0.035 |
| S | ≤0.040 |
| Ni | 3.25–3.75 |
| Mo | 0.20–0.30 |
Weight percent, per the governing standard ranges. Actual values per heat are on the mill certificate.
Properties
| Case hardness (carburized) | 58–63 HRC |
| Core tensile strength | 850–1100 MPa (typ.) |
| Density | 7.85 g/cm³ |
Heat treatment
Carburize 900–930 °C; quench 800–830 °C oil; temper 150–200 °C; refrigerate for retained-austenite control.
Equivalent grades
| Standard | Designation |
|---|---|
| aisi | 4820 |
Compare side by side: 4820 vs 4815
Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.
Applications & Processing
Applications: Large gears and pinions, aerospace transmission parts, heavy industrial gearing.
Processing: As 4815; deep hardenability allows big sections to case harden uniformly.
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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.