Available Shapes
AISI 4140 Alloy Steel
4140 is a chromium-molybdenum alloy steel. The chromium content provides good hardness penetration, and the molybdenum content ensures uniform hardness and high strength. 4140 chrome-molybdenum steel can be oil hardened to a relatively high level of hardness. The desirable properties of the 4140 include superior toughness, good ductility, and good wear resistance in the quenched and tempered conditions.
The 4140 cold finished annealed chromium-molybdenum alloy steel can be heated using various methods to yield a wide range of properties, hence it is often used as stock for forging as it has self-scaling properties. 4140 is capable of resisting creep in temperatures up to 538°C (1000°F) and maintaining its properties even after long exposure at comparatively high working temperatures.
Similar to grade AISI 4130 but with a slightly higher carbon content. The higher carbon content of AISI 4140 gives greater strength and heat treatment capabilities in comparison to AISI 4130.
Applications
Analysis
Forging
Annealing
Stress Relieving
Hardening
Tampering
Applications
AISI 4140 is commonly used for a variety of applications in the oil and gas sector. Typical applications include components such as connecting rods, collets, conveyor pins, gears, stem assemblies, pump shafts, and tool holders.
Analysis
| Carbon | 0.38-0.43% | Chromium | 0.80-1.10% |
| Manganese | 0.75-1.00% | Molybdenum | 0.15-0.25% |
| Silicon | 0.10-0.35% | Phosphorous | 0.035% max |
| Nickel | 0.25% max | Sulphur | 0.040% max |
Forging
Preheat the steel carefully, then raise the temperature to 1150-1200°C for forging. Do not forge below 850°C.
Annealing
Heat the AISI 4140 slowly to 800-850°C and allow enough time for the steel to be thoroughly heated. Cool slowly in the furnace to 480°C followed by air cooling.
Stress Relieving
When parts are heavily machined, ground or otherwise subject to cold work, stress relieving will be beneficial prior to hardening.
Hardening
AISI 4140 steel is usually supplied ready heat treated to 18-22HRC. If further heat treatment is required annealed AISI 4140 should be heated slowly to 840-875°C and after adequate soaking at this temperature quench in oil. Temper as soon as the tools reach room temperature.
Tampering
Heat the AISI 4140 carefully to a suitable temperature selected by reference to a tempering chart or table (usually between 550-700°C, soak at the temperature for 2 hours per 25mm of ruling section, then allow to cool in air. Tempering between 250-375°C is not advised as tempering within this range will seriously reduce the impact value.
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