What is the difference between the Rockwell and Vickers hardness tests?

When it comes to measuring the hardness of materials, engineers and scientists rely on various methods. These methods help them to determine the mechanical properties of materials more effectively. However, when it’s about hardness testing methods, Rockwell and Vickers are considered amongst the most popular ones here. These tests provide valuable insights into a material's resistance to indentation and deformation.

However, here in this article, we will explore the key differences between Rockwell and Vickers hardness tests. So you can understand their methodologies, applications and differences well.

Differences between Rockwell and Vickers hardness test

Let’s have a look at the key differences between Rockwell and Vickers hardness tests that you must know:

What is the Rockwell hardness test?

The Rockwell hardness test is a more commonly used hardness test, which is popular due to its simplicity and versatility.

It helps in measuring the depth of penetration of an indenter into the material under a specified load. The Rockwell hardness testing scale consists of multiple scales, such as A, B, C, D, E, F, G, H, K, etc. These scales are suitable for different materials and loads.

The Rockwell test is primarily used for materials that have a homogeneous structure and are relatively soft.

Methodology of Rockwell hardness test

The methodology of the Rockwell hardness tester involves applying a minor load followed by a major load. In addition to that, it also includes removing the major load while keeping the minor load applied. The depth of penetration is measured, and the Rockwell hardness number (HR) is determined based on the scale that is being used in the respective hardness test.

Above all, the Rockwell test provides a quick and non-destructive measurement. Due to this, it is considered as one of the most suitable hardness tests for quality control and production environments.

What is the Vickers hardness test?

The Vickers hardness test, is another popular hardness test method which is named after its inventor George E. Vickers. This is also a quite popular method used for measuring hardness. It employs a pyramid-shaped diamond indenter. This indenter creates a square-shaped indentation on the surface of the material being tested.

However, the Vickers hardness test is well-suited for materials that are too thin or too hard for the Rockwell test.

Methodology of Vickers hardness test

The Vickers test applies a specific load on the indenter for a certain time. It will result in a surface indentation. The diagonals of indentation are measured, and the Vickers hardness number (HV) is calculated using a formula.

However, the Vickers test provides a more accurate measurement. The fact is especially truer for materials with heterogeneous structures or high hardness values.

Differences between Rockwell and Vickers hardness test to know.

Here are some additional differences between Rockwell and Vickers hardness tests:

· Indentation shape

The Rockwell hardness tester uses a spherical indenter. On the other hand, the Vickers test utilizes a pyramid-shaped diamond indenter. The square indentation of the Vickers hardness test allows for more accurate measurements on various materials.  

· Test Load

The Rockwell test uses different test loads depending on the scale being used. On the other hand, the Vickers test uses a test load ranging from a few grams to several kilograms, depending on the material being tested. The test load is typically lower than that used in the Rockwell test.

· Load application

In the Rockwell hardness tester, a minor load is initially applied, followed by a major load. The major load is then removed, leaving only the minor load. On the other hand, the Vickers test applies a single load on the material.

· Hardness scales

The Rockwell test employs different scales to accommodate various materials. On the other hand, the Vickers test uses a single scale for all materials.

· Hardness Value Calculation

The Rockwell test provides a hardness value based on the depth of penetration of the indenter. The hardness value is determined by the difference between the depth of penetration under the initial test load and the depth of penetration under a subsequent minor load.

The Vickers test provides a hardness value based on the surface area of the indentation made by the diamond-shaped indenter. The hardness value is calculated by dividing the test load by the surface area of the indentation.

· Indenter and Load Range

The Rockwell test uses different indenters and load ranges for different materials. In contrast, the Vickers test uses a standardized diamond pyramid indenter and load range.

Applications of Rockwell and Vickers hardness tests.

The Rockwell and Vickers hardness tests find applications in numerous industries. These industries typically include aerospace, automotive, manufacturing, and materials research. The Rockwell hardness tester is commonly used for softer materials like plastics, rubber, and alloys. On the other hand, the Vickers test is preferred for materials with higher hardness values, such as ceramics, hardened steels, and carbides.

Final Thoughts

Both the Rockwell and Vickers hardness tests play a crucial role in evaluating a material's hardness and mechanical properties. In contrast, the Rockwell test is popular for its simplicity and quick results. Additionally, the Vickers test offers more accurate measurements for a wider range of materials.

However, understanding the differences and applications of these hardness tests helps you to make better decisions.