What are the different hardness testing methods?

The ability of a material to resist indentation or penetration is called hardness. To test the hardness of any material, simply apply a load to drive the indenter into the metal surface. Different methods have been developed to measure this hardness. In this article, we discuss these different hardness testing methods.

Hardness Test Method

There are three different types of hardness testing methods. they are

1. Brinell hardness test

2. Rockwell hardness test

3. Vickers hardness test

These tests are described below

• The Brinell hardness test involves passing a hardened steel ball under load through a metal surface (attempting to make a groove in it).

• The load will be applied with the help of a lever system.

• The hardness of the material will be determined by the Brinell hardness value.

• Brinell Hardness Number = Bending Surface Area of ​​Load/Indentation.

• The size of the ball depends on the material. For example steel we will use a ball with a diameter of 10mm and apply a load of 3000 kg.

Rockwell hardness test

• In Rockwell testing, we use the depth of penetration to determine the hardness of a material, rather than the surface area to determine hardness. (In Brinell testing we use the surface area of ​​the indentation to determine hardness).

• All other actions are the same as the Brinell hardness test.

• However, the formula used here to determine the Rockwell hardness number (Rhn) is hardly different! (There is a dial indicator for Rhn on a Rockwell Hardness Tester.

• There are two scales used to determine hardness according to soft and hard materials.

• Penetrators (indenters) also vary with soft materials (balls) and hard materials (diamond cones).

Vickers hardness test

• The Vickers hardness test is also known as the diamond pyramid hardness test. Because we use a diamond pyramid as an indenter.

• Unlike Brinell testing, we do not need to change indenters for different materials. We can use the same indenter for all material types.

• The Vickers hardness value is determined from the load on the surface area of ​​the indentation.