AISI 8620 is a low-carbon alloy steel designed for case hardening, providing a hard, wear-resistant surface and a tough core. It is widely used for gears, pinions, shafts, bushings, and transmission components.
AISI 8620 is a nickel-chromium-molybdenum alloy steel commonly used in engineering applications requiring a combination of surface hardness, wear resistance, and core toughness. Its relatively low carbon content makes it suitable for carburizing, a heat-treatment process that increases the carbon content at the surface while retaining a comparatively tough core.
The grade is widely used in automotive and industrial transmission systems, including gears, pinions, shafts, bushings, and other components exposed to repeated contact and mechanical loads. Final performance depends on the specified heat-treatment process, case depth, core properties, and component design. Typical Applications: Transmission gears, pinions, shafts, bushings, automotive components, and industrial machinery parts.Final chemical, mechanical properties, dimensions and tolerances are confirmed against the governing specification and purchase order.
| Element | Symbol | Min (%) | Max (%) | Nominal Target |
|---|---|---|---|---|
| Carbon | C | 0.18% | 0.23% | 0.20% |
| Manganese | Mn | 0.70% | 0.90% | 0.80% |
| Nickel | Ni | 0.40% | 0.70% | 0.55% |
| Chromium | Cr | 0.40% | 0.60% | 0.50% |
| Molybdenum | Mo | 0.15% | 0.25% | 0.20% |
| Silicon | Si | 0.15% | 0.35% | 0.25% |
| Phosphorus | P | — | 0.035% | Max 0.035% |
| Sulfur | S | — | 0.040% | Max 0.040% |
| Iron | Fe | Balance | Balance | ~97.2% |
| Condition / Thermal State | Tensile Strength (Rm) | Yield Strength (Re) | Elongation (A5) | Hardness (HBW / HRC) |
|---|---|---|---|---|
| As-Rolled / Hot Rolled | 530 – 640 MPa | 380 – 460 MPa | 20% – 28% | 149 – 183 HBW |
| Cold Drawn | 620 – 720 MPa | 520 – 610 MPa | 12% – 18% | 179 – 217 HBW |
| Normalized (870°C) | 500 – 580 MPa | 350 – 420 MPa | 22% – 30% | 143 – 170 HBW |
| Carburized Core | 950 – 1,150 MPa | 700 – 850 MPa | 12% – 18% | 30 – 40 HRC (300 – 380 HB) |
| Carburized Case (Surface) | — | — | — | 58 – 62 HRC |
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