4720
Data verified4720 is a mid-nickel Ni-Cr-Mo carburizing steel between 8620 and 4320 in cost and core toughness. It serves medium-duty gears that outgrow 8620 but do not justify full 4320 alloy content.
Chemical composition
| Element | Content (%) |
|---|---|
| C | 0.19–0.24 |
| Si | 0.15–0.35 |
| Mn | 0.50–0.70 |
| P | ≤0.035 |
| S | ≤0.040 |
| Cr | 0.35–0.55 |
| Ni | 0.90–1.20 |
| Mo | 0.15–0.25 |
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 | 700–950 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 |
|---|---|
| aisi | 4720 |
Compare side by side: 4720 vs 4320 · 4720 vs 8620
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, transmission parts, worm gears.
Processing: Standard carburizing practice; good machinability in the annealed state.
Need 4720 from stock?
Steel.Wiki is sponsored by Shenzhen NewAsia Special Steel (Nasteel), a special-steel stockholder in Shenzhen stocking mold, tool and alloy steels with EN 10204 3.1 certification.
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.