4140 alloy steel is a chromium-molybdenum low-alloy steel valued for its combination of high tensile strength, toughness, and excellent hardenability. It is one of the most versatile and widely used alloy steels for demanding structural and mechanical applications. Southern Tool Steel stocks 4140 in plate, tube, and flat, hex, round, and square bar, ready to ship nationwide.
What is 4140 Alloy Steel?
4140 is a chromium-molybdenum (Cr-Mo) low-alloy steel that delivers high tensile strength, toughness, and fatigue resistance. The chromium content improves hardenability and wear resistance, while molybdenum adds strength at elevated temperatures and contributes to deep hardening.
In the annealed condition, 4140 machines well using standard tooling. It can also be heat-treated to a wide range of hardness levels, making it adaptable to many application requirements.
Unlike tool steels, 4140 is not intended for cutting or forming tooling applications. It is primarily used for high-strength structural and mechanical components where toughness and fatigue resistance are critical.
Key Attributes of 4140 Steel
- High tensile strength and toughness
- Excellent hardenability
- Good machinability in the annealed condition
- Responds well to heat treatment
- Good fatigue and impact resistance
- Weldable with proper pre- and post-heat treatment procedures
Chemical Composition
|
Element |
Percent (%) |
|
Carbon |
0.38 - 0.43 |
|
Manganese |
0.75 - 1.00 |
|
Chromium |
0.80 - 1.10 |
|
Molybdenum |
0.15 - 0.25 |
|
Silicon |
0.15 - 0.35 |
|
Phosphorus |
0.035 max |
|
Sulfur |
0.040 max |
Applications for 4140 Alloy Steel
4140 is suited for a broad range of high-stress structural and mechanical components. Common applications include:
- Drill collars
- Kelly bars
- Bolts
- Subs
- Couplings
- Reamer bodies
- Rotary table shafting
- Valves
- Hydraulic machinery shafts
- Precision lead screws
- Winch shafts
Heat Treatment
The temperatures below reflect general guidelines for 4140 alloy steel. Actual parameters should be confirmed with a qualified heat treater based on part geometry and end-use requirements.
|
Forging |
Annealing |
Hardening |
Quench |
|
2000-2250°F |
1500-1600°F |
1525 - 1575°F |
Oil or Polymer |
Contact a 4140 Supplier
Southern Tool Steel is a stocking distributor of 4140 alloy steel. We are here to answer your questions and help you identify the right form and condition for your application. Contact us today or check pricing and availability instantly.
Why Partner with Southern Tool Steel?
- Comprehensive Stock: Full range of 4140 alloy steel in various bar shapes, plate, and tube
- Custom Solutions: Precision-cutting and machining services available
- Fast Shipping: Nationwide delivery with quick lead times for in-stock items