Vickers Hardness Testing
Vickers Hardness Testing
Vickers hardness testing is also known as microhardness testing, which is performed using the indenter. The indenter must be of specified geometry where it is pressed in the area of test. The test surface must be of standard materials in order to produce desirable results. Vickers hardness testing is different from other hardness testing like Rockwell testing thus it requires expertise to produce results that are expected. One reason why this hardness testing is different from other testing is that it applies on a single test force. Vickers hardness testing is more like Brinell method simply because it uses a diamond penetrator. The diamond penetrator is shaped in the shape of a pyramid with an angle of 136o in order to perform the test appropriately.
The base of the indentation must have a square shape to provide enough force during testing, (Smith & Sandland, 2010).As the name suggests, this method is appropriate for testing materials that are thin hence it is not suitable for macro hardness testing. It is used to measure and determine microstructures used by individuals within a cross sectional area. Indenters used in microhardness testing must have a square base or a narrow rhombus shape. Before conducting the Vickers microhardness test, sample tests should be done on a smooth surface. They should also be held perpendicular to the material used for testing, (Meyers & Chawla, 2009).
Procedure of conducting Vickers microhardness test is simply but requires concentration. The reason behind this is due to the fact that tests are done for thin materials. The first thing is to select sample for testing. Materials selected for testing should be thin so that the indenter can measure or test for the hardness in accordance. When conducting the hardness tests, some of the things must be met in order to ensure results found are correct. Ensure that indenter used for testing plus all other materials is clean. The platen for Vickers hardness testing should also be clean. Select a spot that will be used in your test and it should be have the required diameter in all sides. The loading handle should start with the minor load position leaning in the forward side. Most of The Vickers hardness tests fail simply because individuals do not follow instructions appropriately, (Smith & Sandland, 2010).
The light knob should be adjusted in order to ensure that it is in the center before the testing process starts. With the fine knob at the center, the crank CW is then turn in order to ensure the material and the indenter is to contact. The turning should continue until the SET line of the indenter is near horizontal mark. This is seen on the screen present in the indenter. The delicate adjustment knob then helps to line up and develop a precise setting of the material during the testing process. The loading handle is the pushed away from the line. This helps apply enough load to develop a situation possible to measure the hardness of the material. The process of putting load should continue until the screen display stops moving. After this dial, the load to 100 and repeat the process in the above for the same, (Meyers & Chawla, 2009).
Reference:
Meyers, R & Chawla, H. (2009).Mechanical Behavior of Materials. Prentice Hall, Inc
Smith, R.L. & Sandland, G.E. (2010). An Accurate Method of Determining the Hardness of Metals, with Particular Reference to Those of a High Degree of Hardness.Proceedings of the Institution of Mechanical Engineers: Vol. I, p 623–641
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