Knowing the hardness testing method is not enough; many other questions are also necessary to answer while adopting any hardness test for your material. Such as when to use which hardness test? How much time does it take? Which test is better for a specific situation? How much does every hardness test cost? How do you get accurate results while performing the test? and many more.
You can find answers to all these questions about the Brinell and Rockwell test in this blog, as we are going to clarify the difference between the two tests. Without any further discussion, let’s start.
I. What is the Rockwell Hardness Test?
According to the ASTM Standard E-18, the Rockwell method is the most commonly used hardness test method across the world. It is used as the static hardness testing method. It can be used to measure the hardness of all metals except the one which is causing too much variation, or the indentation caused is very large for the test, or in some prohibited cases due to sampling size or shape. The test measures the hardness of the object by measuring the value of permanent depth caused by indentation. The indentation is developed with the application of a test force on the indenter.
Related Article: What is the Rockwell Scale?
Related Article: What are the Advantages and Disadvantages of the Rockwell Method?
II. What is the Brinell Hardness Test?
The Brinell test is a hardness testing method that is defined in ASTM standards as E10. The brinell testing method can apply to materials that have very rough surfaces or coarse structures for testing such as casting and forgings. Usually, other hardness tests cannot be applied to such materials. Due to the rough surface, the test load applied in the Brinell test is very high = 3000kgf and indenter use is of 10mm diameter. This causes a deep indentation which passes through rough and inconsistencies of the surface. The Brinell indentation is measured by an optical system, for example microscope.
Related Article: What are the Advantages and Disadvantages of the Brinell Method?
III. What is the Difference between Rockwell and Brinell?
Test Method
The method to perform the Rockwell hardness test is easier and simple than the Brinell hardness testing method. Rockwell hardness test can be performed by measuring the value of depth of the indentation. Brinell hardness test is performed by measuring the value of the diameter of indentation produced by the indenter.
Indenters
In the Brinell hardness test method, only one type of indenters is used while in Rockwell hardness we use two types of indenters for the procedure of the test. In the Brinell test, the intender is a calcareous ball or hard metal. In the Rockwell hardness test, intenders are a small steel ball (or soft objects) and a diamond cone for hard materials.
Test Force
Test force or load used in the Brinell test is very high. It starts from 1kgf to 3000 kgf, while in the Rockwell test, the test force starts from 10 Kgf (minor) to 60, 100, 150 kgf (primary).
Accuracy
Rockwell hardness testing is the most standardized test; its results are more accurate than the Brinell hardness test.
Duration
The duration of indention in both tests is different. Brinell hardness test is slower to perform with the estimated time of 30 to 60 seconds, while Rockwell hardness is fast enough to show results in 10-15 seconds.
Application
The Brinell hardness testing method is mainly used to check the hardness of soft and medium-hard materials with rough and coarse surfaces. At the same time, the Rockwell hardness test can be applied for all soft and hard metals, such as steel, alloy and aluminum, except for one with many variations.
Calculation
Commonly HB is measured by calculating the ratio of given force F (N) and the surface of the fingerprint S (mm2):
The formula to calculate Brinell Hardness test is HBW = (F*0.102/ S); S = π* D* h.
The formula to calculate Rockwell hardness test is HRB = 130 – (e/0.002); HRC = 100 – (e/0.002)
IV. FAQs on Rockwell and Brinell Hardness Test
1. Is Rockwell more Accurate than Brinell?
Yes, even though both Rockwell and Brinell hardness test methods fall in the category of static test methods. Still, Rockwell’s results are more accurate than Brinell results because of their simple test procedure and less complexity.
2. Why is Brinell Better than Rockwell?
Brinell test is better than the Rockwell hardness test because it can measure the hardness of though material which is not measurable by another test like Rockwell. Brinell test measures the hardness of objects with coarse and refought surfaces and provides accurate results.
3. Why is the Rockwell test better than Brinell or Vickers?
Rockwell hardness testing method is the most affordable, easy, and quick process than any other test like Brinell or Vicker. The Rockwell testing product needs no prior material preparation. Also, you can measure the value of hardness without using any other extra optical instrument. That’s why the Rockwell hardness testing method is the most commonly used method.
4. Which hardness test is more accurate?
Rockwell hardness test is the most accurate test in the list of hardness testing methods because
- It has a simple procedure
- Results are easily visible
- Nondestructive testing method
- Applies differential depth method
- Decreases errors of mechanical imperfections
- Less sensitive to imperfections
Conclusion
Hardness tests of metals are essential to manufacture reliable big machines and automobiles. The hardness test should be first selected according to the needs of the material. By this analysis, we can conclude that the Rockwell hardness testing method is the most reliable and efficient method, and it is in use globally. But Other methods like the Brinell hardness test have its own perks and usability. To enhance your knowledge about hardness testing methods and manufacturers, visit our website and find a lot of relative information.