AISI 4340 / 34CrNiMo6 Ultra-High Strength SteelForging Metallurgy & Specs
Nickel-Chromium-Molybdenum Steel for Extreme Shock, Impact & Dynamic Torsion. Hot-forged and precision-machined in Rajkot, Gujarat strictly up to 50 kg max piece weight with 100% Optical Emission Spectrometry (OES) PMI testing and EN 10204 3.1 MTC compliance.
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AISI 4340 / 34CrNiMo6 Ultra-High Strength Steel (UNS G43400 / 1.6582 / 34CrNiMo6 / EN24) offers a minimum tensile strength of 1000 – 1200 MPa (145 – 174 ksi) and yield strength of 850 – 1000 MPa (123 – 145 ksi) with 300 – 360 HBW (32 – 38 HRC) hardness. Manufactured by Jayesh Forge in Rajkot, Gujarat strictly up to 50 kg per piece, this alloy features Requires surface electroplating or ceramic barrier coating. Tested per ASTM A388 Level II ultrasonic standards with EN 10204 3.1 MTC inspection.
AISI 4340 / 34CrNiMo6 Ultra-High Strength Steel Chemical Analysis (% by Weight)
| Element | Chemical Symbol | Minimum (%) | Maximum (%) | Specification Role |
|---|---|---|---|---|
| Carbon | C | 0.38% | 0.43% | Controls base tensile strength & core hardness |
| Nickel | Ni | 1.65% | 2.00% | Improves notch toughness, cryogenic ductility & hardenability |
| Chromium | Cr | 0.70% | 0.90% | Forms passive chromium oxide layer for oxidation & corrosion resistance |
| Manganese | Mn | 0.60% | 0.80% | Combines with sulfur, increases hardenability and hot workability |
| Molybdenum | Mo | 0.20% | 0.30% | Prevents chloride pitting and enhances high-temperature creep strength |
| Silicon | Si | 0.15% | 0.35% | Deoxidizer during melting; improves high-temperature scaling resistance |
* Ladle chemical analysis verified using optical emission spectrometer (OES) calibrated to NIST certified reference materials. Full chemical results recorded on EN 10204 3.1 MTC.
AISI 4340 / 34CrNiMo6 Ultra-High Strength Steel Mechanical Properties
Ultimate breaking stress threshold
Elastic deformation limit
Plastic ductility before rupture
Surface indentation resistance
Cross-sectional necking ductile ratio
Dynamic fracture energy absorption
Thermal Cycle & Machining Parameters
1180°C – 880°C (2150°F – 1615°F)
Oil quench from 830°C, double-tempered at 550°C – 620°C for optimum dynamic fracture toughness
Requires surface electroplating or ceramic barrier coating
Machinability: 50% of AISI 1212 • Difficult; requires specialized austenitic buttering layers or full post-weld re-austenitizing and quench
International Equivalent Material Grades
Forged Components Manufactured in AISI 4340
Heavy Transmission Couplings
Ultra-high torque couplings for mining mills and high-speed locomotive drives.
Forged Aircraft & Power Shafts
Impact-resistant driveshaft forgings with continuous concentric grain lines.
AISI 4340 Frequently Asked Technical Questions
The 1.65% to 2.00% Nickel addition in AISI 4340 significantly increases hardenability throughout thick cross-sections while drastically lowering the ductile-to-brittle transition temperature, preventing catastrophic brittle failure under shock loading.
Related Industrial Metallurgy Specifications
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Manufactured in Rajkot, Gujarat strictly up to 50 kg max piece weight. 4-hour quote turnaround committed.