SAE AISI 4340 Steel Properties, Heat Treatment, Equivalent, Hardness Chart, Density, Machinability
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Family: Alloy Steel
Performance Ratings
Performance Radar
Composition
Mechanical Properties
| Hardness (Rockwell) |
Chemical Composition
| Element | Percentage (%) |
|---|---|
| % | 38 |
| C | – |
| P | 0.035 |
| S | 0.04 |
| Cr | 0.70-0.90 |
| HB | 250 |
| Mn | 0.60-0.80 |
| Mo | 0.20-0.30 |
| Ni | 1.65-2.00 |
| Si | 0.15-0.35 |
| HRC | 24 |
| ISO | – |
| sfm | – |
| Notes | Steel Bars, Carbon and Alloy, Hot-Wrought |
| m/min | – |
| mm/rev | – |
| in./rev | – |
| mm (in.) | 150 (6) |
| MPa (ksi) | 876 (127) |
| °C (°F) | 705 (1300) |
| Gpa (106 psi) | 200 (29) |
| J (ft · lbf) | 102 (75) |
| Steel Grade (UNS) | Premium Quality Alloy Steel Blooms and Billets for Aircraft and Aerospace Forgings |
| Brinell hardness, HB | Quenched + Tempered |
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Description
AISI 4340 steel (UNS G43400) is an ultra-high strength medium carbon low alloy steel, which combines deep hardenability, high ductility, toughness and strength, and has high fatigue resistance and creep resistance. It is not particularly affected by tempering and embrittlement, and exhibits good strength retention at high temperatures and is not easily softened. In thin sections, this steel is air-hardened. In practice, it is usually oil quenched. The following tables and lists give 4340 alloy steel datasheet and specification including chemical composition, physical properties and mechanical properties, heat treatment, welding, etc. AISI 4340 steel material chemical composition is listed in the following table based on cast analysis.