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4140 & 4150 Heat Treated Tgp (Rc 28/34) Alloy Shafting

4140 and 4150 TGP steel bar - precision-ground for industrial use

We stock AISI 4140 and AISI 4150 steel in a turned ground & polished finish (TGP). Call or Email Us For a Free Quote. Material is quench & tempered, stress relieved, machine straightened, and turned ground & polished. We offer an extensive inventory of hard-to-find sizes in both English and Metric sizes. Length options include (10/12 Ft Random Lengths, 20/24 Ft Random Lengths and Custom Cut-To-Lengths). Alloy 4140 and 4150 are widely used materials as an alternative to carbon steel where strength and fatigue are of concern.

Typical Mechanical Properties

Brinell Hardness – 269/341BHN
Tensile Strength – 156,000 PSI
Yield Strength – 123,500 PSI

Available Lengths

10/13 Ft R/L
20/26 Ft R/L
Custom Cut-To-Lengths

Rounds (Inches)

For Metric 4140 & 4150 Sizes Click Here
1/4 1-3/16 2-1/4 3-5/16 4-1/2
5/16 1-1/4 2-5/16 3-3/8 4-3/4
3/8 1-15/16 2-3/8 3-7/16 4-15/16
7/16 1-3/8 2-7/16 3-1/2 5
1/2 1-7/16 2-1/2 3-9/16 5-1/4
9/16 1-1/2 2-9/16 3-5/8 5-7/16
5/8 1-9/16 2-5/8 3-11/16 5-1/2
11/16 1-5/8 2-11/16 3-3/4 5-15/16
3/4 1-11/16 2-3/4 3-7/8 6
7/8 1-3/4 2-7/8 3-15/16 6-1/2
15/16 1-7/8 2-15/16 4 7
1 1-15/16 3 4-1/4 7-1/2
1-1/16 2 3-1/16 4-3/8 8
1-1/8 2-1/16 3-1/4 4-7/16

Typical Applications for 4140/4150 TGP Shafting

4140/4150 TGP is high strength, precision-ground alloy shafting that is commonly used in industries where high-wear resistance is needed. These include:

  • Hydraulic and Pneumatic Shafts
  • Motor and Pump Shafts (especially high-load environments)
  • Axles and Spindles
  • Heavy Machinery Components
  • Tie Rods and Piston Rods
  • Gears and Pinions (where post-machining hardening is not required)

Need help determining which type of alloy steel is right for your industry or project? Contact us as Speciality Steel for more details and information.

Available Sizes and Ordering Options for 4140/4150 TGP Shafting at Specialty Steel

We have an extensive inventory of 4140 and 4150 TGP shafting and specialize in both standard and hard-to-find diameters. Here are some of the sizes and ordering options available:

  • Rounds (Inches)
  • Metric Sizes
  • Length Options: 10/13 Ft Random Lengths, 20/26 Ft Random Lengths, and Custom Cut-To-Lengths.

Why Choose Heat Treated (RC 28-34) Alloy Steel?

Heat treated alloys steels can provide:

  1. High Strength: Tensile strength exceeding 150,000 PSI, significantly stronger than standard annealed bars.
  2. Fatigue Resistance: The stress-relieved condition minimizes internal stresses, making it ideal for shafts, axles, and highly stressed parts subject to repeated loading.

No Pre-Machining Heat Treatment: Delivered ready for final machining, saving time and eliminating the risk of distortion and scaling from post-machining heat treatment.

The Advantages of Turned, Ground & Polished (TGP) Alloy Steel

The TGP finish on certain alloy steel can provide high surface quality essential for close-tolerance applications:

  • Surface Finish: Ensures a smooth, consistent finish suitable for bearing surfaces and sealing applications.
  • Dimensional Accuracy: Held to extremely tight tolerances for straightness and diameter, which is critical for precision machinery.

The Disadvantages of Turned, Ground & Polished (TGP) Alloy Steel

While TGP finishes are known for its smoothness and accuracy, there are some disadvantages machinists should be aware of like:

  • Heavier Weight: Since TGP alloy steel has a high density, it can be incredibly heavy which can serve as a disadvantage in the application process.
  • Higher Cost: Alloying elements like chromium, nickel, and vanadium are significantly more expensive than plain iron, making TGP alloy steel more costly.

Frequently Asked Questions About 4140/4150 Heat Treated TGP Shafting

1. What is The Functional Difference Between 4140 and 4150 Steel Shafting, and Which is Generally Preferred for High-Stress Rotational Applications?

Both 4140 and 4150 are chromium-molybdenum alloy steels used in high-strength, heat-treated conditions. The primary chemical difference is the carbon content: 4150 contains a higher percentage of carbon. This incremental carbon increase results in higher tensile strength and hardness for 4150 after quenching and tempering. 

However, this gain in hardness comes at the expense of ductility and impact toughness. For most general high-stress shafting applications that require an optimal blend of strength, fatigue resistance, and necessary toughness to withstand shock loading, 4140 is typically the preferred choice.

The TGP coating provides immediate manufacturing advantages by delivering material ready for final machining, eliminating the need for pre-processing. The heat treatment (Q&T) stabilizes the microstructure,  boosting chip control and reducing tooling wear compared to softer grades. This process also includes stress-relief and precision straightening.

This eliminates the internal stresses common in hot-rolled bar stock, preventing dimensional distortion or warpage. This consistency and quality chip management can always equate to overall cost savings.

The tolerance for 4140 TGP will be dependent on its diameter, but typically a common tolerance for 4140 TGP is +.000 inch/-.001 when the diameter is smaller. It is always good practice to confirm the diameters with your steel supplier for accurate application.

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