ThePipingMart Blog Metals 8630 Steel vs 4140 – What’s the Difference

8630 Steel vs 4140 – What’s the Difference

8630 Steel vs 4140

Choosing the right steel for your machined parts can be overwhelming. With so many different materials, getting lost in a sea of technical jargon and numbers is easy. Two of the most common materials you might come across are 8630 steel and 4140. While these steels are similar in many respects, some key differences are worth noting. In this post, we’ll look at both materials and help you decide which is right for your application.

What is 8630 Steel?

First, let’s consider 8630 steel. This material is an alloy steel composed primarily of iron, nickel, and chromium. It is heat-treated to provide exceptional toughness, strength, and hardenability. One of the key benefits of 8630 steel is its high fatigue strength, making it an excellent choice for high-stress applications. This steel is often used in the aerospace and oil and gas industries, as well as in heavy machinery and equipment.

What is 4140?

On the other hand, 4140 steel is another popular material for machined parts. It is also an alloy with less nickel and chromium than 8630 steel. Like 8630, it is heat-treated to achieve high strength and hardness. One of the key advantages of 4140 steel is its excellent wear resistance. This makes it a great choice for applications where parts like gears and bearings will be subjected to friction and abrasion.

Difference Between 8630 Steel and 4140

There are a few key differences to note when comparing the two materials. Firstly, 8630 steel is a bit more expensive than 4140 due to its higher nickel content. However, it also has a higher strength-to-weight ratio than 4140, making it a great choice for applications where weight is a concern. Additionally, 8630 steel is more resistant to impact and fatigue than 4140, making it a better choice for high-stress applications.

On the other hand, 4140 steel is more machinable than 8630, meaning that it is easier to work with and can be used to create more complex geometries. It is also less brittle than 8630, making it less likely to crack or fail under load. However, it is worth noting that 4140 steel can become more brittle at high temperatures, so there may be better choices for applications exposed to extreme heat.

  • 8630 steel is a low alloy steel that contains chromium, molybdenum, and manganese.
  • 4140 steel is a high carbon steel that contains chromium and molybdenum.
  • 8630 steel is stronger and harder than 4140 steel.
  • 4140 steel is easier to weld than 8630 steel.
  • 8630 steel is more resistant to wear and tear than 4140 steel.


Choosing the right steel for your application ensures that your machined parts perform as intended. While 8630 and 4140 steel have unique advantages and disadvantages, understanding the differences can help you make an informed decision. If you require a material with exceptional fatigue strength and high resistance to impact, then 8630 steel may be the way to go. However, if wear resistance and machinability are your top priorities, 4140 steel may be the better choice. Ultimately, the right steel for your application will depend on a range of factors, including your budget, your machining capabilities, and the specific demands of your application.

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