AISI 4140 / 42CrMo4 High-Tensile Alloy SteelForging Metallurgy & Specs
Chromium-Molybdenum Quenched & Tempered Alloy Steel for High Fatigue & 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 4140 / 42CrMo4 High-Tensile Alloy Steel (UNS G41400 / 1.7225 / 42CrMo4 / EN19) offers a minimum tensile strength of 850 – 1000 MPa (123 – 145 ksi) and yield strength of 650 – 750 MPa (94 – 109 ksi) with 260 – 310 HBW (28 – 32 HRC normalized & tempered) hardness. Manufactured by Jayesh Forge in Rajkot, Gujarat strictly up to 50 kg per piece, this alloy features Low; requires plating, black oxide, or liquid nitriding (Tenifer) for wear and corrosion. Tested per ASTM A388 Level II ultrasonic standards with EN 10204 3.1 MTC inspection.
AISI 4140 / 42CrMo4 High-Tensile Alloy Steel Chemical Analysis (% by Weight)
| Element | Chemical Symbol | Minimum (%) | Maximum (%) | Specification Role |
|---|---|---|---|---|
| Carbon | C | 0.38% | 0.43% | Controls base tensile strength & core hardness |
| Chromium | Cr | 0.80% | 1.10% | Forms passive chromium oxide layer for oxidation & corrosion resistance |
| Manganese | Mn | 0.75% | 1.00% | Combines with sulfur, increases hardenability and hot workability |
| Molybdenum | Mo | 0.15% | 0.25% | Prevents chloride pitting and enhances high-temperature creep strength |
| Silicon | Si | 0.15% | 0.35% | Deoxidizer during melting; improves high-temperature scaling resistance |
| Phosphorus | P | — | 0.04% | Restricted to prevent temper embrittlement |
| Sulfur | S | — | 0.04% | Strictly controlled for cleaner grain flow and micro-cleanliness |
* 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 4140 / 42CrMo4 High-Tensile Alloy 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 quenched from 845°C, tempered at 550°C – 650°C to achieve target tensile and hardness
Low; requires plating, black oxide, or liquid nitriding (Tenifer) for wear and corrosion
Machinability: 55% of AISI 1212 • Requires 250°C – 350°C preheat and post-weld stress relief (PWHT) to prevent martensitic embrittlement
International Equivalent Material Grades
Forged Components Manufactured in AISI 4140
Heavy Duty Forged Couplings
Precision splined and keyed couplings for heavy gearboxes and wind turbines.
AISI 4140 Frequently Asked Technical Questions
Jayesh Forge supplies AISI 4140 forgings in either Annealed (soft for rapid CNC roughing) or Quenched & Tempered (Q&T / 'Condition T' or 'U' per EN 10083-3) with verified MTC hardness and tensile test coupons.
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.