Copper plays an important role in the life of human beings. From the delivering of electricity to the supply of water, copper made all things possible. It allows the electric current to passes through it with the same voltages; it is the good conductor of electricity. The copper is used in the electric appliances, almost every high-quality motors have the copper wires in them. In the past, the cutlery item is made from the copper with are a good conductor of the heat and cold. Copper itself is soft in nature but when you mix it with any other metal it becomes hard.

What is the hardness of metals?

Hardness is termed as the resistance of the metals to indentation. Hardness doesn’t remain forever it depends on the strength and the plasticity of the metal. The hardness of the metal depends on the method of measurement. The measurement results are expressed in the quantitative figures.  The resistance in the metal can make them hard, resistance refer to the four different things. They are scratching, abrasion, cutting, and penetration. The different properties of the metal give them the ability to resist or deformed permanently when the load is applied.  The greater resistance to deformation shows the greater hardness of the materials.

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The hardness of the material is commonly used for the quality testing and quality control of the materials. The main reason for the quality control of the materials is because they are fast and known to be the nondestructive tests. There are some of the important measurements for the hardness of the materials described below:

Indentation hardness: it is the simple method in which we can measure the resistance of the material to deformation when the constant pressure or load from the sharp object is applied to it. It can be measured through the Rockwell, Brinell, shores, and Vickers.

Scratch hardness: in this method, we measure the resistant of the metal for permanent plastic deformation or fracture due to the friction of the sharp object on it. For the measurement of this method, the Mohs scale is used.

Rebound harness: rebound hardness is the method in which the diamond-tipped hammer is dropped from the certain height on the specific material to check its hardness. The Bennett hardness and the Leeb rebound hardness scale are used to measuring the rebound hardness.

The conversion table is used to convert the one scale to another; it is used for the practices. There is the individual measurement scale for each of these classes.

Properties of copper: (related to hardness)

The copper is used for the sheeting and in the form of strips commonly. It is consist of 99.9 percent pure copper and the 0.1 percent may be the other metal. The pure form of the copper is soft which is extremely malleable and can be used for the different applications like intricate ornamental works. In the past, it is commonly used in the constructions of the buildings. The heavy gauge materials are used along with the copper because copper has a low strength than other metals. With the passage of time, the copper is replaced with other strong metals in the building constructions.

Many years ago the cold-rolled copper is introduced and the gauge of the other materials is reduced. The cold-rolled copper has a long life with low maintenance than other materials. Cold rolled copper is hard and is less malleable than the soft tamper copper. It is the popular form of the copper which is used in construction purposes.

The common mechanical properties of the copper are strength, hardness, and ductility which determine its condition. Copper is can be converted into the hard from soft; the method used to range the copper is cold working. Annealed (soft) copper is 40HV of hardness with the tensile strength of 200 N/mm2 and after the cold work, it has the hardness of 110 HV with the tensile strength of 360 N/mm2. The ductility of the annealed copper is greater than the cold-worked copper. You can increase the strength and the hardness of the copper easily. The common way of increasing the strength of the copper is through the alloying, but it can affect the conductivity of the electricity. The hardening process is done by heat treatment and can result in the tensile strength of 1500 N/mm2.

Test for hardness:

There are different types of the test to determine the hardness of the metals, but in the case of the copper, there are only three different types of tests used to determine its hardness. The types of tests are discussed below:

Rockwell Test:

The Rockwell Hardness test is a popular test to check the hardness of the copper.

Optical Surface Rockwell & Vickers Hardness Tester HV30, HV60, HV100

It consists of thirty different tests with the number of loads and indenter configurations. Scale B and C are only used for the thickness of the 1mm and can be used for the copper alloys with this thickness. For the thin products the testing should be done through the superficial scales N and T. the hardness of the thin materials are checked with the microhardness scales.

Brinell Test:

It is the large and extensive indentation test, which is not suitable for the thin and wire type materials. It is popular for testing the large rods, bars, plates, and other heavy materials. The testing of these materials will produce large indentations. The Brinell test is run only for the materials who are thicker than the minimum of 3.2 inches.

Vickers and Knoop Tests:

The Vickers test is also known as the diamond pyramid hardness test. The load uses in this test is between 1 to 120 kg. If the weight of the material is less than 1 kg than the Vickers microhardness test will perform.  And the knop test is specially designed for the micro indentation hardness testing. The testing is performing with the help of the elongated indenter.

All above the tests are designed to check the hardness of the copper, the test selection is depended on the quality and the type of the copper.