AISI 4140
Alloy Steel AISI 4140 Supplier in Tunisia
AISI 4140 alloy steel is a chromium-molybdenum low-alloy steel known for its high strength, good hardenability, toughness, and fatigue resistance. It is widely used in the manufacture of mechanical components that operate under heavy loads, repeated stresses, and demanding industrial conditions.
The mechanical properties of AISI 4140 can be adjusted through appropriate heat treatment, allowing it to meet different requirements for hardness, strength, and toughness. It is commonly used in oil and gas, mining, power generation, automotive engineering, heavy machinery, and general industrial applications.
Emirerri Steel supports the sourcing of AISI 4140 alloy steel according to project requirements, product form, dimensions, applicable specifications, and quality documentation, subject to availability.
Key Properties
- High mechanical strength: Suitable for components subjected to significant mechanical loads.
- Good hardenability: Allows the development of required mechanical properties through appropriate heat treatment.
- Good toughness: Provides a useful balance between strength and resistance to mechanical failure when correctly processed.
- Fatigue resistance: Suitable for selected applications involving cyclic loading, depending on design and surface condition.
- Wear resistance: Can be improved through suitable hardening and tempering processes.
- Machinability: Generally suitable for machining in an appropriate material condition.
- Versatile fabrication: Used in bars, forgings, and other product forms according to applicable specifications and supplier capabilities.
AISI 4140 Chemical Composition
| Chemical Element | Typical Composition (%) |
|---|---|
| Carbon (C) | 0.38–0.43 |
| Manganese (Mn) | 0.75–1.00 |
| Silicon (Si) | 0.15–0.35 |
| Chromium (Cr) | 0.80–1.10 |
| Molybdenum (Mo) | 0.15–0.25 |
| Phosphorus (P) | 0.035 max. |
| Sulfur (S) | 0.040 max. |
Note: These are commonly published composition ranges for AISI 4140. Exact limits depend on the applicable product specification and its edition. The material test certificate should be used to verify the supplied heat.
AISI 4140 Mechanical Properties
| Mechanical Property | Typical Indicative Value |
|---|---|
| Tensile strength | Approximately 850–1,000 MPa |
| Yield strength | Approximately 650–850 MPa |
| Elongation | Approximately 10–20% |
| Brinell hardness | Approximately 250–300 HBW |
| Impact toughness | Depends on heat treatment and test conditions |
AISI 4140 Physical Properties
| Physical Property | Approximate Value |
|---|---|
| Density | 7.85 g/cm³ |
| Modulus of elasticity | 205 GPa |
| Thermal conductivity at room temperature | 42–45 W/m·K |
| Specific heat capacity | 460–480 J/kg·K |
| Mean coefficient of thermal expansion | Approximately 12–13 × 10⁻⁶/K |
| Poisson’s ratio | Approximately 0.27–0.30 |
| Electrical resistivity | Approximately 0.22–0.25 µΩ·m |
Note: Physical-property values are approximate and may vary with temperature, material condition, and reference source.
Grade Specification Comparison and Equivalents
AISI 4140 is commonly compared with several international alloy-steel grades. However, similar designations do not automatically establish full technical equivalence.
| Standard or Country | Grade or Reference |
|---|---|
| AISI / SAE (USA) | 4140 |
| EN (Europe) | 42CrMo4 |
| EN Material Number | 1.7225 |
| DIN (Germany) | 42CrMo4 |
| JIS (Japan) | SCM440 |
| GB (China) | 42CrMo |
| BS (United Kingdom) | 708M40 — comparable designation |
| AFNOR (France) | 42CD4 — historical comparable designation |
Before substituting one grade for another, verify chemical composition, mechanical properties, product dimensions, heat treatment, inspection requirements, and the applicable product standard.
Corrosion Resistance
AISI 4140 does not provide the corrosion resistance of stainless steel. Although chromium is present in its composition, its concentration and metallurgical role do not make it a stainless grade.
Exposure to moisture, seawater, chemicals, or aggressive industrial atmospheres may cause corrosion unless appropriate protection is applied.
Protection may consist of the following, depending on the working environment:
Protective coatings compatible with the application.
Temporary corrosion-inhibiting oils during storage and transportation.
Suitable surface treatments where technically appropriate.
Controlled storage conditions to reduce moisture exposure.
The choice of material should be carefully considered for applications that are severely corrosive or maritime. Stainless steel or a corrosion-resistant alloy may be more suitable, depending on service conditions.
Heat Resistance
AISI 4140 is used in mechanical components exposed to varying temperatures, but it is not specifically designed as a creep-resistant steel for prolonged high-temperature pressure service.
Elevated temperatures can affect hardness, tensile strength, and the properties established by heat treatment. Performance depends on the actual temperature, duration of exposure, material condition, and applied stress.
For high-temperature applications, allowable operating conditions must be determined using applicable engineering data and design requirements. Components used in pressure equipment or prolonged high-temperature service may require a grade specifically qualified for those conditions.
Heat Treatment
Heat treatment is used to adjust the mechanical properties of AISI 4140 to suit the intended application.
Annealing
Annealing can improve machinability and provide a suitable material condition for subsequent manufacturing operations. The process depends on product dimensions and the required final properties.
Normalizing
Normalizing may help refine and homogenize the steel’s microstructure, depending on the manufacturing process and subsequent treatment.
Quenching
Quenching involves heating the steel according to a defined cycle and cooling it under controlled conditions. It can increase hardness and strength but may also introduce internal stresses.
Tempering
Tempering is commonly performed after quenching to adjust hardness and improve toughness. The selected tempering cycle depends on the required mechanical properties.
Heating temperatures, holding times, and cooling methods must be selected according to the product form, section size, applicable specification, and required properties. Appropriate inspections should confirm that the final material condition meets the order requirements.
Welding
Welding AISI 4140 requires careful procedure selection because its carbon content and hardenability can increase the risk of cracking and the formation of hard regions in the heat-affected zone.
Depending on the component and welding conditions, precautions may include:
Evaluating the material condition and weldability before welding.
Applying suitable preheating.
Controlling interpass temperature.
Selecting compatible filler materials.
Controlling cooling rates.
Applying post-weld heat treatment when required by the qualified procedure or component specification.
Performing specified non-destructive examinations.
For critical components, welding should follow a qualified welding procedure developed and approved by competent personnel.
Fabrication
AISI 4140 can be used for machining, forging, and other manufacturing operations, depending on the product form and material condition.
Machining
Turning, milling, drilling, and grinding parameters should be selected according to hardness, tooling, and required surface finish. Annealed material may be easier to machine, while quenched-and-tempered material may require specialized tooling and cutting conditions.
Forging
Forging must be carried out within a suitable temperature range for the grade and process. Cooling after forging and any subsequent heat treatment must be controlled to achieve the required properties.
Cutting and Forming
Cutting and forming methods depend on thickness, geometry, material condition, and dimensional tolerances. The selected process should minimize surface defects and unwanted changes in material properties.
Inspection After Fabrication
Depending on the application, inspection may include dimensional checks, surface examination, hardness testing, mechanical testing, and non-destructive examination where required by the purchase specification.
Applications
AISI 4140 is widely used in industries that require reliable mechanical strength and controlled material properties.
Oil and Gas Industry
Mechanical components for drilling equipment.
Shafts and axles subjected to high loads.
Machined components for industrial equipment.
Selected components manufactured to project specifications.
Mechanical Engineering
Transmission shafts.
Gears and pinions.
Axles, spindles, and machine components.
High-strength fasteners where permitted by the relevant specification.
Industrial machinery parts.
Mining Industry
Heavy-equipment mechanical components.
Power-transmission parts.
Components exposed to repeated mechanical stresses.
Parts used in material-handling and processing machinery.
Power Generation and General Industry
Production machinery components.
Forged and machined parts.
Mechanical elements requiring a defined combination of strength and toughness.
Industrial equipment components selected for the intended service conditions.
The suitability of AISI 4140 must be assessed against operating loads, temperature, environmental exposure, applicable standards, and required certified mechanical properties.
Emirerri Steel – AISI 4140 Alloy Steel Supplier
Emirerri Steel supports industrial customers in sourcing alloy-steel materials for mechanical and industrial applications. We review AISI 4140 enquiries according to the required dimensions, product form, applicable standards, heat-treatment condition, and quality documentation.
We serve project requirements across the oil and gas, petrochemical, power generation, mining, mechanical engineering, and industrial equipment sectors in Tunisia and North Africa.
To request a quotation, please provide the required grade, product form, dimensions, quantity, applicable standard, heat-treatment condition, and certification requirements. Availability and delivery schedules are confirmed at the quotation stage.
Conclusion
AISI 4140 alloy steel is a versatile chromium-molybdenum grade used for mechanical components requiring high strength, good hardenability, and adjustable properties through heat treatment. Correct material selection depends on the product specification, material condition, design requirements, and operating environment.
Emirerri Steel can review your AISI 4140 alloy-steel requirements and support sourcing in accordance with your project’s technical specifications, subject to availability.
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