AISI 4140 Alloy Steel | 1.7225 | SCM440 | 42CrMo4

4140 steel round bar
Grade 4140 steel round bar turned qt q+t

AISI?4140?Alloy steel material stockholders and suppliers from China-OTAI SPECIAL STEEL . we have more 16 years experience in 4140 steel plate, round bar, flat bar, square supply.AISI 4140 alloy steel is chromium, molybdenum, manganese containing low alloy steel. It has high fatigue strength, abrasion and impact resistance, toughness, and torsional strength. The following datasheet gives an overview of AISI 4140 alloy steel.

4140 alloy steel material is a?high?quality Quenched and Tempered Alloy Structural steel, It?belong to the high quality medium carbon alloy steel, Oil Quenched & Tempered Hardenss is 28-34 HRC.4140 Annealing delivery hardenss less than 250HB.

Related Specifications?ASTM A29/A29M DIN EN 10083/3 JIS G4053 GB GB/T 3077

1. SAE AISI 4140 steel Form of Supply

ASTM / AISI 4140 Alloy structural steel, we can supply the round bar, steel flat bar, plate, hexagonal steel bar and square, block. 4140 alloy steel Round bar?can be cut to your required lengths as one offs or multiple cut pieces. Rectangular pieces can be cut?from flat bar or plate to your specific sizes. Ground tool steel bar can be supply, providing a quality precision finished bar to tight tolerances.

2. AISI?4140 equivalent material

  • ?JAPAN??: JIS SCM440 alloy steel?
  • ?GERMANY? : DIN WN-r 1.7255 / 42CrMo4 steel alloy
  • ?CHINA? : ?GB 42CrMo steel
  • ?BRITISH? : BS 708M40

3. AISI 4140 alloy steel Chemical composition

ASTM A29/29M C Si Mn Cr Mo P S
4140 0.38~0.43 0.15~0.35 0.75~1.00 0.80~1.10 0.15~0.25 ≤0.035 ≤0.040
DIN WN-r C Si Mn Cr Mo P S
1.7225 0.38~0.45 ?≤0.40 0.60~0.90 0.90~1.20 0.15~0.30 ≤0.035 ≤0.035
GB/T C Si Mn Cr Mo P S
42CrMo 0.38~0.45 0.17~0.37 0.50~0.80 0.90~1.20 0.15~0.25 ≤0.030 ≤0.030
BS C Si Mn Cr Mo P S
708M40 0.36~0.44 0.10~0.35 0.70~1.00 0.90~1.20 0.15~0.25 ≤0.035 ≤0.035
JIS C Si Mn Cr Mo P S
SCM440 0.38~0.43 0.15~0.35 0.60~0.85 0.90~1.20 0.15~0.30 ≤0.030 ≤0.030

4. Applications

DIN 4140?Tool steel is a alloy structural steel, 4140 is used for engineering structural, like high tensile shafts, bolts and nuts, gears, pinions and spindles. Locomotive traction with the big gear, supercharger drive gear, pressure vessel, rear axle, gear load of connecting rod and a spring clip,4140 can also be used to under 2000 m deep well of oil drill pipe joint and the fishing tool, and can be used for bending machine mould, etc

5. Supply Size range

Hot Rolled 4140 steel bar: ?5mm-200mm

Forging 4140 steel bar: ?140mm-3000mm

Hot rolled 4140 steel plate: Thickness 10mm-200mm x width 100-2300mm

Forged 4140 material steel plate:?Thickness 150-1500mm x Width 100 x 3000mm

Others 4140 material have not specified size, pls contact our?experienced sales team.

6. 4140 alloy steel Heat treatment

4140 heat treatment

  • Annealing
    AISI 4140 alloy steel is annealed at 872°C (1600°F) followed by slowly cooling in the furnace.
  • Tempering
    AISI 4140 alloy steel can be tempered at 205 to 649°C (400 to 1200°F) depending upon the desired hardness level. The hardness of the steel can be increased if it has lower tempering temperature. For example, tensile strength of 225 ksi cab be achieved by tempering at 316°C (600°F), and a tensile strength of 130 ksi can be achieved by tempering at 538°C (1000°F).
  • Hardening
    AISI 4140 alloy steel can be hardened by cold working, or heating and quenching.


Mechanical Properties of 4140 alloy steel

Properties Metric Imperial
1.Tensile?strength 655?MPa 95000?psi
2.Yield?strength 415?MPa 60200?psi
3.Bulk?modulus?(typical?for?steel) 140?GPa 20300?ksi
4.Shear?modulus?(typical?for?steel) 80?GPa 11600?ksi
5.Elastic?modulus 190-210?GPa 27557-30458?ksi
6.Poisson’s?ratio 0.27-0.30 0.27-0.30
7.Elongation?at?break?(in?50?mm) 25.70% 25.70%
8.Hardness,?Brinell 197 197
9.Hardness,?Knoop?(converted?from?Brinell?hardness) 219 219
10.Hardness,?Rockwell?B?(converted?from?Brinell?hardness) 92
11.Hardness,?Rockwell?C?(converted?from?Brinell?hardness.?Value?below?normal?HRC?range,?for?comparison?purposes?only) 13 13
12.Hardness,?Vickers?(converted?from?Brinell?hardness) 207 207
13.Machinability?(based?on?AISI?1212?as?100?machinability) 65 65

AISI 4140 alloy steel has high ductility. It can be formed using conventional techniques in the annealed condition. It requires more pressure or force for forming because it is tougher than plain carbon steels.

AISI 4140 alloy steel can be welded using all conventional techniques. However, the mechanical properties of this steel will be affected if it is welded in the heat treated condition, and post weld heat treatment should be performed.

AISI 4140 alloy steel is forged at 926 to 1205°C (1700 to 2200°F)

10.Hot Working
AISI 4140 alloy steel can be hot worked at 816 to 1038°C (1500 to 1900°F)

11.Cold Working
AISI 4140 alloy steel can be cold worked using conventional methods in the annealed condition.


AISI 4140 steel round bar and flat sections can be cut to your required sizes. ASTM 4140?tool steel ground bar can also be supplied, providing a high quality tool steel precision ground tool steel bar to your required tolerances. SAE 4140?steel is also available as Ground Flat Stock / Gauge Plate, in standard and nonstandard sizes.

Contact our experienced sales team to help you with your AISI 4140 alloy steel questionsadn enquiry?by?Email or Telphone.?The 4140 alloy steel questions will be reply in 24 hours.


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