We manufacture forging ingots, billets, and blooms in AISI 4340 Steel, a nickel-chromium-molybdenum low alloy steel renowned for its exceptional strength, toughness, hardenability, and fatigue resistance.
AISI 4340 is widely used in applications requiring high mechanical performance under heavy loads and cyclic stresses.
It is commonly used for manufacturing forged shafts, gears, crankshafts, axles, fasteners, connecting rods, pressure vessel components, and other critical engineering forgings for the aerospace, automotive, oil & gas, power generation, mining, and heavy engineering industries.
| Element | Content (%) | Function / Effect |
| Carbon (C) | 0.38 – 0.43 | Provides strength and hardness |
| Manganese (Mn) | 0.60 – 0.80 | Improves toughness and hardenability |
| Silicon (Si) | 0.15 – 0.35 | Enhances strength and acts as a deoxidizer |
| Nickel (Ni) | 1.65 – 2.00 | Improves toughness, strength, and impact resistance |
| Chromium (Cr) | 0.70 – 0.90 | Enhances hardenability, wear resistance, and corrosion resistance |
| Molybdenum (Mo) | 0.20 – 0.30 | Improves high-temperature strength and hardenability |
| Phosphorus (P) | Max. 0.035 | Controlled impurity for improved toughness |
| Sulphur (S) | Max. 0.040 | Controlled impurity for better machinability |
| Iron (Fe) | Balance | Base metal |
(Properties may vary depending on section size and heat treatment conditions.)
AISI 4340 is commonly referenced as:
AISI 4340 offers an exceptional combination of high strength, toughness, fatigue resistance, and hardenability. Its nickel-chromium-molybdenum alloy composition provides excellent mechanical performance even under severe loading conditions. It is an ideal material for manufacturing critical forged components that require superior reliability, durability, and long service life in demanding industrial applications.
| Grade | Carbon (%) | Nickel (%) | Key Applications | Comments |
| AISI 4140 | 0.38 – 0.43 | — | Shafts, Gears, General Engineering | Cr-Mo alloy steel |
| AISI 4340 | 0.38 – 0.43 | 1.65 – 2.00 | Aircraft Components, Gears, Shafts | Excellent toughness and fatigue strength |
| EN24 | 0.36 – 0.44 | 1.30 – 1.70 | Heavy-Duty Shafts and Gears | British equivalent |
| 34CrNiMo6 | 0.30 – 0.38 | 1.30 – 1.70 | Heavy Engineering Components | DIN equivalent |
AISI 4340 is a nickel-chromium-molybdenum low alloy steel offering exceptional strength, toughness, fatigue resistance, and hardenability. It is widely used for manufacturing forged shafts, gears, crankshafts, axles, fasteners, connecting rods, pressure vessel components, and other critical engineering forgings for the aerospace, automotive, oil & gas, power generation, mining, and heavy engineering industries.
Kesari Alloys manufactures forging ingots, billets, and blooms in AISI 4340 Steel to meet the demanding requirements of high-performance forging applications.