Hardness test procedures make use of an indenter probe that is displaced into a surface under a particular load. The indentation usually has a pre-set dwell time. Traditional mechanical testing calls for the measurement of size and depth as a way to determine hardness. Hardness testing comes in two ranges: macrohardness and microhardness. Macrohardness covers testing that involves an applied load of more than 1 kg or roughly 10 Newton (N). With applied loads less than 10 N, microhardness testing is usually used for thin specimens, plated surfaces, thin films or smaller samples. The two most popular microhardness testing techniques used nowadays are Vickers and Knoop hardness tests.


For more exact and repeatable Atmosphere Annealing Los Angeles results, microhardness testing has to be responsible for the effects of sample preparation, size and environment. Samples should be perpendicular to the indenter tip and fit in the sample stage. A very rough surface may decrease the accuracy of indentation data; an established method for polishing samples is best to use. The microhardness tester should be totally separated from vibrations. For samples having several phases or grain size variations, statistical data will be required.


Vickers Hardness 


In the Vickers hardness test, a Vickers indenter will be pressed against a surface at a pre-defined force held for about 10 seconds. Once the indentation is completed, the resulting indent is examined optically to determine the lengths of the diagonals, which is important in determining the size of the impression.


Some degree of operator bias in this procedure must be expected, specifically in the lower range of the applied load. The length of indentation diagonals, as per ASTM E384-11, must be more than 17 microns in length. For coated samples with coating thicknesses less than 60 microns, this test does not apply.


For several kinds of samples, the contact depth is different from the displacement depth since the surrounding material becomes elastically deflected during the indentation process. In addition, this effect also has an impact on accuracy and precision for Wheelabrate Los Angeles data. 


Knoop Hardness


Like the Vickers hardness test, the Knoop hardness test is also a microhardness technique. The process involves a Knoop indenter pressing into a surface for measuring hardness. However, the more rectangular or elongated shape of the Knoop indenter makes it look different from a Vickers indenter, which is used in microhardness testing, or a Berkovich indenter, which is used in nanoindentation. The Knoop hardness test method is often used for the microhardness testing of lighter loads, and requires meticulous sample preparation. Knoop hardness testing is used on samples where indentations have to be close together, or should be on a sample's edge, both gaining benefits from the different probe shape.



A particular load is applied for a pre-defined dwell time. Unlike the Vickers hardness method, the Knoop test method solely uses the long axis. Using a chart, the indentation measurements that come out of this are then converted to a Knoop hardness number.