AISI 4340 Steel | 36CrNiMo4 | 1.6511 | EN24 | 817M40 | SNCM439

AISI 4340 steel is a medium carbon, low alloy steel known for its toughness and strength in relatively large sections. AISI 4340 is also one kind of nickel chromium molybdenum steels. 4340 alloy steel is generally supplied hardened and tempered in the tensile range of 930 – 1080 Mpa. Pre hardened and tempered 4340 steels can be further surface hardened by flame or induction hardening and by nitriding. The 4340 steel has good shock and impact resistance as well as wear and abrasion resistance in the hardened condition. AISI 4340 steel properties offer good ductility in the annealed condition, allowing it to be bent or formed. Fusion and resistance welding is also possible with our 4340 alloy steel. ASTM 4340 material is often utilized where other alloy steels do not have the hardenability to give the strength required. For highly stressed parts it is excellent choice. AISI 4340 alloy steel can also be machined by all customary methods.

Due to availability the ASTM 4340 grade steel is often substituted with European based standards 817M40/EN24 and 1.6511/36CrNiMo4 or Japan based SNCM439 steel. You have the detailed data of 4340 steel below.

1. AISI Alloy 4340 Steel Supply Range

4340 Steel Round Bar: diameter 8mm – 3000mm
4340 Steel Plate: thickness 10mm – 1500mm x width 200mm – 3000mm
4340 Steel Grade Square: 20mm – 500mm

Surface Finish: Black, Rough Machined, Turned or as per given requirements.

2. AISI 4340 Steel Specification and Relevant Standards

3. ASTM 4340 Steels And Equilvalents Chemical Composition

4. AISI Alloy 4340 Steel Mechanical Properties

Thermal Properties

5. Forging of 4340 Alloy Steel

Preheat the steel 4340 first, heat up to 1150°C – 1200°C maximum for forging, hold until temperature is uniform throughout the section.

Do not forge below 850 °C. 4340 has good forging characteristics but care must be taken when cooling as the steel shows susceptibility to cracking. Following forging operation the work piece should be cooled as slowly as possible. And cooling in in sand or dry lime is recommended etc.

Otai Steel is one of leading supplier of AISI 4340 steel for your different application as above. And we supply 4140 steel, 4130 steels as well. Contact me and let me know your requests anytime.

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