4140 steel

AISI 4140 alloy steel round bar sheet plate has high fatigue strength and low notch sensitivity. Low-temperature impact toughness is also very high, no obvious temper brittleness. It is mainly used after quenching and tempering state. It is used to manufacture high-strength parts under impact loads and the fittings with large cross-sections and other stressed members. Such as the horizontal eccentric shaft of the horizontal forging machine, the crankshaft of the forging press, and etc. And the equivalent grade for it is DIN 1.7225 and JIS SCM440. 4140 Steel properties and heat treat as below.

AISI 4140 Steel Characteristics

  1. It is low alloy steel with chromium, molybdenum, and manganese.
  2. Great toughness, fatigue strength, abrasion and impact resistance.
  3. It is widely be used in the industry due to its excellent versatility and usefulness.
  4. The higher carbon content in it, the higher the strength and heat treatment capabilities it is.
  5. It can be oil hardened to relatively high hardenability.

4140 Steel Application

4140 steel is medium hardenability steel with good strength and good comprehensive mechanical properties after heat treatment. It has good manufacturability. The maximum temperature of use is 427 °C. It can be used to make turbine fastener, tool bodies, forming dies, brake dies and etc. And it also as the material of Oil deep well drill pipe joints and fishing tools below 2000m.

4140 Steel Physical Properties

Density7.85 g/cm³0.284 lb/in³
Melting point1416°C2580°F

1.7225 Steel Mechanical Properties

Tensile strength655 MPa95000 psi
Yield strength415 MPa60200 psi
Bulk modulus(typical for steel)140 GPa20300 ksi
Shear modulus(typical for steel)80 GPa11600 ksi
Elastic modulus190-210 GPa27557-30458 ksi
Poisson's ratio0.27-0.300.27-0.30
Elongation at break(in 50 mm)25.70%25.70%
Hardness, Brinell197197
Hardness, Knoop(converted from Brinell hardness)219219
Hardness, Rockwell B(converted from Brinell hardness)9292
Hardness, Rockwell C(converted from Brinell hardness. Value below normal HRC range, for comparison purposes only)1313
Hardness, Vickers(converted from Brinell hardness)207207
Machinability(based on AISI 1212 as 100 machinability)6565

aisi 4140

4140 Steel Grade Equivalent Chart

StandardASTM A29 / A29M-05EN 10083/3-2006JIS G4053-2008

4140 Steel Chemical Composition

ASTM A29 / A29M-050.38-0.430.75-1.00Max 0.035Max 0.0400.15-0.350.80-1.100.15-0.25-
EN 10083/3-20060.38-0.450.60-0.90Max 0.025Max 0.035Max 0.400.90-1.200.15-0.30-
JIS G4053-20080.38-0.430.60-0.90Max 0.030Max 0.0300.15-0.350.90-1.200.15-0.30≤0.25

4140 Steel Round Bar Sheet Plate Heat Treatment


At the annealed condition, 1.7225 alloy tool steel has good machinability.


DIN 1.7225 steel has high ductility. It can be formed using conventional techniques in the annealed condition. It is required more pressure or force for forming because it is tougher than plain carbon steels.


1.7225 alloy steel can be welded using all advanced techniques. But, the mechanical properties of it will be affected if it is welded in the heat treated condition, and post weld heat treatment should be performed.

Heat Treatment

1.7225 tool steel is heated at 845°C(1550°F) followed by quenching in oil. Before hardening, it can be normalized by heating at 913°C (1675°F) for a long period of time followed by air cooling.


It is forged at 926 to 1205°C(1700 to 2200°F)

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Hot Working

4140 steel can be hot worked at 816 to 1038°C(1500 to 1900°F)

Cold Working

1.7225 steel can be cold worked using conventional methods in the annealed condition.


Heat it to 800℃ – 850℃, hold until temperature is uniform throughout the section and cool in furnace.


Heat 1.7225 alloy steel to 870℃ – 900℃, hold it until the temperature is uniform throughout the section, soak for 10 – 15 minutes and cool in still air.


DIN 1.7225 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 tensile strength of 130 ksi can be achieved by tempering at 538°C (1000°F).


DIN 1.7225 alloy steel can be hardened by cold working, or heating and quenching.

4140 Steel Round Bar Sheet Plate Supply Range

Round Bar

Specification: diameter: 10mm – 1000mm; length: 2000mm-5000mm
Surface: Black Surface/Bright Surface/ Grinded/Peeled/Turned


Specification: thickness: 50-120mm; width: 2000mm-2300mm; length: 3000mm-5800mm
Surface: Black Surface/Bright Surface/ Grinded/Peeled/Turned

Stock List

4140 Steel Stock List 2020-6-11

Other specifications are determined by daily stock. Customization is also acceptable.

We have our own cutting and processing equipment. Specifications can be cut and customized according to your requirements.

We are a professional special steel stockist and supplier with a high-quality stand for many years. As a professional 4140 steel supplier, the min 4140 steel price is about $0.63/KG, please contacts us for any request for it. Songshun Steel always with you.