How to test the hardness of metals?

The very idea, that is hardness testing, can be done in a multitude of ways. This particular type of testing may just be the most practically relevant and commonly used method for evaluating metals of all kinds. It looks into the metallic object and gives a deep insight in regards to its properties.

Why test its hardness? It simply must be tested in order to conclude whether or not it is suitable for any sort of task (e.g. could it be used as a building material?). Its durability and hardiness must also be made sure of because that would determine the sort of use the metal could be put to. Let’s move on to how exactly metal hardness can be tested.

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Rebound Principle

For this test, a hammer with a diamond point is released from a predetermined height. Once the hammer hits the metal and rebounds, the height of that rebound is measured and is used to determine hardness.

Indentation

Testing by way of indentations is a rather simple concept. A force is applied by an indenter (e.g. a drill) to the metal being tested and the depth of the indentation would indicate the hardness of that metal. This test can be done with little complications or a lot of complications depending on the need for accuracy. A firm force could be applied with hands and the surface of the metal observed for penetrations. For more accurate results, a specialized instrument could be put into use to apply a fixed force and measure the depth of the indentation. The depth is usually more when the metal is softer.

Micro-hardness Test

Simply put, the area of the penetration is calculated as opposed to the depth in order to determine the hardness of the metal.

Abrasion Testing

The wearing down of the metal may indicate hardness but it comparatively takes much longer to carry out this specific test in contrast to other tests. Add to that the fact that the results may not be satisfactory and it is generally recommended that other tests be done as well.

Scratch Hardness Test

As is evident from the name, this test has a specialized instrument dragged across the surface of the metal. Any indentation, or lack of it, would indicate hardness.

Conclusion

In conclusion, investigating the hardness of metals is hugely relevant in regards to industrial or commercial use. While no test is perfect and the standards are varied, metals can be tested with relative certainty using the tests mentioned above.