This medium carbon alloy grade is widely used for many general purpose parts requiring high tensile strength and toughness. 4140 contains chromium and molybdenum as alloying elements and may be heat treated over a wide range to give the combined hardness may be required, this steel is readily flame or induction hardened.
AISI 4140 Chrome- High Tensile Steel, generally supplied hardened and tempered to condition “T” in sections up to 100mm, with a tensile strength of 850-1000 MPa and aiming for this strength range in larger sections. It offers a very good balance of strength, toughness and wear-resistance.
Properties:
WEAR RESISTANCE —— Medium
TOUGHNESS —— Very High
RESISTANCE TO SOFTENING EFFECT OF ELEVATED TEPERATURE —— Low
DEPTH OF HARDENING ——- Medium
MACHINABILITY ——- Medium
GRINDABILITY ——- High
DISTORTION IN HEAT TREATING —— Medium
SAFETY IN HARDENING ——- low
RESISTANCE TO DECARBURIZATION —— Medium
TYPICAL APPLICATIONS:
Axles, conveyor parts, crow bars, gears, logging parts, spindles, shafts, sprockets, studs, pinions, pump shafts, rams, ring gears, etc.
Chemical Composition:
| Carbon | Silicon | Manganese | Chromium | Molybdenum |
| 0.40% | 0.25% | 0.85% | 1.00% | 0.25% |
Relative Grades：
GB/T 3007, 42CrMo; DIN 1.723; EN 10883-1 42CrMo4; JIS G4105 SCM400
Typical Mechanical properties
| Diameter | Yield Strength | Tensile Strength | Elongation | Impact Izod | Hardness |
| mm | MPa | MPa | % | J | HB |
| 50 | 770 | 930 | 17 | 90 | 275 |
| 100 | 710 | 920 | 15 | 70 | 270 |
| 200 | 570 | 850 | 14 | 60 | 250 |
1) Forging
Preheat the steel carefully, then raise the temperature to 1150-1200°C for forging. Do not forge below 850°C.
2)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.
3)Stress Relieving
When parts are heavily machined, ground or otherwise subject to cold work, stress relieving will be beneficial prior to hardening.
4)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.
5)Tempering
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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Post time: Dec-20-2018