4140/4142 Alloys Round Bar Stock

4142 and 4142 alloys are used in various industrial applications.

4140/4142 Alloys

4140 is a Chromium-Molybdenum alloy steel that is one of the most commonly used alloy steels.

Thus, the primary alloying elements are chromium and molybdenum. As a result, 4140 is used in applications that require high wear resistance and high temperatures. Meanwhile, 4142 alloys are used in various industrial applications, including tools and other types of equipment. After heat treatment, it is a medium carbon chromium-molybdenum alloy steel with high strength and toughness.  

O'Hare 4140/4142 Alloys Round Bar Stock

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Machinability and other Processes

4140 has a machinability rating of 66 percent, which is excellent. However, the presence of molybdenum contributes to the uniformity of hardness and high strength. Also, it is a complicated metal to weld, but it is possible if the section is preheated before welding and then stress relieved after welding.

4142 Alloy Steel is a through-hardening alloy steel with high strength and toughness after heat treatment. It possesses excellent fatigue and impact resistance. Alloy steels with tensile and yield strengths in 4140/4142 are available. The machinability of steel increases as it is hardened and tempered.


Axles, shafts, tools bodies, tie rods, stubs, couplings, reamers, gears, racks are the common applications of 4140/4142 Alloys.



Poisson’s ratio 

Elastic modulus

Bulk modulus 

Shear modulus 

0.284 lb/in³  


27557-30458 ksi  

20300 ksi   

11600 ksi

Chemical Properties









0.40-0.45 0.380 – 0.430

0.80-1.10 0.80 – 1.10

0.75-1.10 0.75 – 1.0

0.15-0.25 0.15 – 0.25

 0.035 0.035

0.15-0.30 0.15 – 0.30

0.040 0.040

96.725 Balance

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