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How Hard is 4140 Steel – A Complete Guide

How hard is 4140 Steel

Did you know that there are over 60 grades of steel? Each type has its unique properties, making it suitable for different applications. One grade that is gaining popularity among metalworkers and machinists is 4140 steel. Let’s look at why this grade of steel is so popular and how hard it is.

What is 4140 Steel?

4140 steel, also known as Chromoly or chromium molybdenum, is a medium carbon alloy made up of chromium, molybdenum, iron, carbon, and manganese. It is one of the world’s most widely used grades of alloys due to its versatility and strength. It can be used in various applications, such as automotive parts, construction materials, tools and dies, shafts, tubing and more.

Hardness Rating

The hardness rating of 4140 steel depends on the heat treatment used during manufacturing. Generally speaking, it has a Rockwell C rating between 26-30 when it is not heat treated. After heat treatment, this steel grade can have a Rockwell C rating between 58-65. This means that it can be hardened and tempered to meet specific requirements for strength and durability, depending on the application for which it will be used.


Overall, 4140 steel is an incredibly strong material with excellent wear resistance, making it ideal for many different applications like automotive parts, construction materials, tools & dies. Its hardness rating varies depending on whether or not it has been heat treated but generally ranges from 26-65 Rockwell C scale (HRC). Its versatility makes this steel grade very popular among metalworkers and machinists!

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