# SAE 8620 steel

Nickel-chromium-molybdenum case-hardening steel: chemistry, supplied condition, case/core requirements and procurement limits.

Reviewed: 2026-11-01

Tags: materials, steel, alloy-steel, case-hardening

## Identity and intended use

Interlloy's **typical 8620 core** data after **carburizing and oil quenching at 840°C** give **785 MPa yield at 11 mm**, **590 MPa at 30 mm** and **490 MPa at 63 mm**. The entries sit in a typical table despite the “min” label. Verify the actual section, case and core separately for the finished part. [Interlloy carburized core table](https://www.interlloy.com.au/our-products/case-hardening-steels/8620-case-hardening-steel/?output=pdf)

SAE 8620 is a low-carbon nickel-chromium-molybdenum alloy steel used for carburized components that need a wear-resistant surface supported by a tougher core. Encore lists gears, pinions, splined shafts and piston pins among its applications. Its **2016 Product Manual**, page 31, distinguishes carburized use from uncarburized heat-treated use and describes hot-rolled/as-rolled supply, with larger diameters hot forged/as forged. Those are supplier descriptions, not a guarantee that every item sold as 8620 arrives in one condition. [Encore Metals, 2016 Product Manual](https://www.encoremetals.com/wp-content/uploads/2024/02/Encore-Metals-Product-Manual_2016-Final.pdf)

## Chemistry and designation boundaries

Metallus's **Practical Data for Metallurgists, nineteenth edition, copyright 2024**, lists the following composition ranges for standard alloy steel 8620. These are mass percentages, not nominal additions or finished-part mechanical properties. [Metallus, standard alloy steel tables](https://metallus.com/wp-content/uploads/2024/01/Practical-Data-Guide-For-Metallurgists-Metallus-2024.pdf)

| Element | Listed range, mass % |
|---|---:|
| Carbon | 0.18–0.23 |
| Manganese | 0.70–0.90 |
| Chromium | 0.40–0.60 |
| Nickel | 0.40–0.70 |
| Molybdenum | 0.15–0.25 |

This abbreviated table omits other limits; use the full governing specification for acceptance. SAE's public description of **J404_200901, revised January 27, 2009**, distinguishes heat composition from permitted check-analysis variations under J409. It covers specified alloy-steel product forms and directs sheet/strip and mechanical tubing to separate ASTM specifications. “SAE 8620” therefore does not by itself identify a universal product specification or dimensional tolerance. [SAE J404_200901](https://saemobilus.sae.org/standards/j404_200901-chemical-compositions-sae-alloy-steels)

Keep 8620 and 8620H separate in structured records. Atlas's **April 2006** 8620H sheet explicitly associates the H suffix with guaranteed hardenability and publishes Jominy bands. It also lists different composition ranges for its H-grade product. Do not infer that a chemistry-only 8620 certificate meets a specified hardenability band. [Atlas 8620H, pages 1–2](https://atlassteels.com.au/documents/Atlas8620H.pdf)

Voestalpine Australia's product page labels DIN and BS designations as **nearest standards**. Treat such cross-references as comparison leads: verify chemistry, hardenability, product requirements and certification before approving substitution. The page has no verified technical revision date. [Voestalpine HPM Australia, AISI 8620](https://www.voestalpine.com/highperformancemetals/australia/en-au/products/aisi-8620/)

## Supplied steel versus finished case and core

Separate three states in a drawing or database:

- **Incoming stock:** dimensions, surface finish, annealed/as-rolled condition and acceptance hardness.
- **Carburized and hardened component:** surface hardness, case-depth definition and core requirements.
- **Finished component:** remaining case after grinding, dimensional accuracy and surface condition.

Atlas's historical supply example is annealed, maximum 212 HB, typically 170–200 HB. Cooling-medium selection depends on geometry, desired properties and hardenability. [Atlas 8620H, page 1](https://atlassteels.com.au/documents/Atlas8620H.pdf)

Carburizing and quench/temper are distinct operations. Encore's historical example gives approximately 63 HRC case hardness after tempering at 150 °C and approximately 58 HRC after tempering at 232 °C. These are process-dependent examples, not two interchangeable grade ratings. The manual's treatment is not a production recipe for an arbitrary section or furnace. [Encore Metals, 2016 Product Manual, page 31](https://www.encoremetals.com/wp-content/uploads/2024/02/Encore-Metals-Product-Manual_2016-Final.pdf)

Specify where hardness is measured and how case depth is defined. A surface indentation, a cross-section hardness traverse and a core tensile specimen answer different questions. Record the test method, acceptance location and sampling arrangement; do not silently store all three as a single “hardness” property.

## Bounded section-size example

Interlloy's primary supplier table is headed **typical mechanical properties for core—carburized and oil quenched at 840 °C**. It shows the following section dependence. Although individual cells say “min”, the enclosing table remains typical guidance, not a universal delivery guarantee. No issue date was verified; the source's related-specification list includes older editions. [Interlloy, 8620 case-hardening steel](https://www.interlloy.com.au/our-products/case-hardening-steels/8620-case-hardening-steel/?output=pdf)

| Test section | Core tensile strength | Core yield strength, listed minimum |
|---|---:|---:|
| 11 mm | 980–1270 MPa | 785 MPa |
| 30 mm | 780–1080 MPa | 590 MPa |
| 63 mm | 690–930 MPa | 490 MPa |

For a comparison only, the listed 30 mm yield value is 195 MPa below the 11 mm value: 785 − 590 = 195 MPa, about 24.8% of 785 MPa. This arithmetic does not predict an intermediate diameter or a gear tooth's local properties. The same source reports that uncarburized 8620's low carbon content limits its response to flame/induction hardening; changing surface-hardening route requires separate qualification. [Interlloy, core table and introductory guidance](https://www.interlloy.com.au/our-products/case-hardening-steels/8620-case-hardening-steel/?output=pdf)

## Process planning and acceptance

Use the following as an engineering review sequence, rather than a generic heat-treatment instruction:

1. Establish load, wear location, geometry and required core support before selecting final properties.
2. Agree stock condition and machining allowances with the material supplier and heat treater.
3. Define case-depth criterion, hardness locations, protected surfaces and dimensional acceptance after finishing.
4. Qualify the complete carburize/harden/temper/finish route on representative geometry.
5. Retain heat identity and process/test records with the accepted component.

Joining also needs its own procedure. Atlas's historical sheet places welding before carburizing and calls for controlled preheat, low-hydrogen practice and cooling. Its numbers should not be copied into a repair instruction for a finished carburized part. Obtain a procedure addressing the actual condition, section and subsequent treatment. [Atlas 8620H, page 3](https://atlassteels.com.au/documents/Atlas8620H.pdf)

Keep test basis, units and source edition with the value.

## Related reference

[Grades, tempers and conditions](../grades-tempers-and-conditions.md)