Aluminum belongs to the boron group of metals in the periodic table with an atomic number of 13 and Al is its symbol.
The hardness of metal means its ability to resist drilling, abrasion, deformation, wear/tear or indentation. Aluminum is one of the highly important ferrous non-metals.
It is widely used in various manufacturing industries, transport industries, packaging purposes, electricity purpose, for making various utensils, machinery, and equipment.
Surmise to say aluminum has almost unending uses, so it becomes important to check its hardness for the usage of various purposes. Various tests are employed for the testing hardness of aluminum. Among many two are described here-
Leeb Hardness Test/Leeb Rebound Hardness Testing
Leeb and Brandestini developed this test in 1975 as an alternative to uncommon and complicated hardness testing instruments.
It is one of the most widely used tests employed to test the hardness of a metal. In this test, an object of predetermined mass is struck at the surface of the sample under investigation with a known force.
The instrument measured the collision rebounding velocity of an impacting object when it almost 1mm apart from the test sample. The ratio of rebounding velocity to the impacting velocity gives Leeb Hardness.
If the material under investigation is harder more will be the Leeb Hardness Number as with more velocity the impact object will rebound.
Leeb Hardness Test cannot be used to measure the hardness of very fine sheets of aluminum. Based on indenter and impact body which differ in mass, material, size and weight different harness and impact device units are used.
Brinell Hardness Testing
During 1900 in Sweden this method was invented by Dr.J.A.Brinell to investigate the hardness of metals.
It is one of the oldest methods for determining the hardness of a metal. In this test, the indenter is used which is a carbide ball. The sample to be tested is pressed with the indenter under controlled force for a specific period.
After the test is complete the carbide indenter is removed and the diameter of the round indent in the sample is measured. The Brinell Hardness Number lies between HB50 to HB750.
The more the value of the sample the harder the sample used for the test is. Brinell Hardness Number (BHN) can be derived by dividing the force applied by the spherical surface area of the indent.