Vickers hardness tester

1, the use of Vickers hardness tester

Vickers hardness test is mainly used for material research and scientific experiments. The small-load Vickers hardness test is mainly used to test the hardness of small precision parts, the hardness of the hardened layer and the effective hardened layer depth, the surface hardness of the coating, thin sheet material and thin wire Hardness, hardness in the vicinity of the cutting edge, hardness of the dental material, etc. Since the test force is small, the indentation is also small, and the appearance and performance of the sample may not be affected. Micro Vickers Hardness Test is mainly used for metallurgy and metallographic research. It is used to determine the hardness of each component phase in the metallurgy, and is used to study the brittleness of refractory compounds. Micro Vickers hardness test is also used for testing of very small or very thin parts. The thickness of parts can be as thin as 3 μm.

Widely used to measure the microhardness of test pieces such as micro and thin test pieces and surface dialysis coatings, and to measure the Knoop hardness of brittle and hard materials such as glass, ceramics, agate and synthetic gemstones. It is a research institute, factory and The quality supervision department conducts material research and testing of ideal hardness testing equipment. Scope of application: heat treatment, carbonization, hardened layer, surface coating, steel, non-ferrous metals and small and thin parts. The Knoop hardness of brittle and hard materials such as glass, ceramics, agate, and synthetic gemstones can be measured with the Knoop indenter.

2. Test principle of Vickers hardness tester

The Vickers hardness tester uses a 49.03 to 980.7N load and presses the square-cone diamond with an opposing surface angle of 136° into the surface of the pressing material. After the specified time, the diagonal length of the indentation is measured, and then the formula is used. Calculate the size of the hardness. It is suitable for hardness determination of large workpieces and deeper surface layers. Vickers hardness is still a small load Vickers hardness, test load <1.949.03N, it applies to the determination of the hardness of the thin workpiece, tool surface or plating; micro Vickers hardness, test load <1.961N, suitable for metal foil, Determination of the hardness of very thin surface layers.

The quotient of the test force divided by the indentation surface area is the Vickers hardness value. Vickers hardness value calculation formula: HV = constant × test force / indentation surface area ≈ 0.1891 F/d2 ............ where: HV --- Vickers hardness sign; F --- test force (unit N); d ———— The arithmetic mean (in mm) of the two diagonals d1 and d2 of the indentation. In practice, the Vickers hardness value can be obtained by looking up the table according to the diagonal length d. According to the national standard, the diagonal length of Vickers hardness indentation ranges from 0.020 to 1.400mm.

1, advantages:

Vickers hardness tester for thinner Vickers hardness measurement. The positive quadrangular pyramid diamond indenter was pressed into the surface of the sample under the test force. After the prescribed time, the test force was removed and the diagonal length of the indentation surface was measured. The indentation of the Vickers hardness tester is square, with clear outlines and accurate diagonal measurements. Therefore, the Vickers hardness test is the most accurate of the commonly used hardness test methods, and its repeatability is also good. This is more than the Brinell hardness tester. superior.

The Vickers hardness tester measures a wide range of values, from very soft materials (several Vickers hardness units) to very hard materials (3000 Vickers hardness units).

The greatest advantage of the Vickers hardness tester is that its hardness value is independent of the test force. As long as it is a material with uniform hardness, the test force can be arbitrarily selected and its hardness value does not change. This is equivalent to having a uniform ruler over a wide range of hardness. This is better than the Rockwell hardness test.

In the medium and low hardness range, the Vickers hardness test and Brinell hardness test results in similar hardness values ​​on the same homogeneous material. The Vickers hardness tester can have a test force as small as 10 gF and a very small indentation, making it particularly suitable for testing thin and small materials.

2. Disadvantages

Vickers hardness tester is low in efficiency, requires higher test technology, and requires a higher finish for the surface of the sample. Usually, special test samples are required. The operation is troublesome and time-consuming. It is usually used only in the laboratory.

According to the work practice over the years, before starting the verification and repair work, it is necessary to start with adjusting the level of the workbench, and then observe whether the spindle, lever, lift screw, buffer mechanism and measuring device are normal and flexible. Ensure a basic understanding of device performance. Then solve the situation one by one.

1, fault type:

( 1 ) The failure of the charging indicator and measuring lamp is off;

( 2 ) Measurement of turbidity in the microscope, invisible or invisible impression;

( 3 ) The indentation is not in the mind or slightly rotates the table, and the position of the indentation changes greatly.

2. Solution

( 1 ) First check whether the power supply is connected, and then check the switch, light bulb, etc. If these factors are still not clear, it is necessary to see whether the load is added or the switch is normal.

( 2 ) This must be adjusted from the adjustment of the microscope's irritability and light. After the adjustment is still unclear, the objective lens and the eyepiece must be turned separately, and the three flat mirrors with dashed, solid, and engraved lines inside the mirror should be moved to observe the problem carefully. On which mirror surface, and then remove it, wipe it clean with Zhangxian cotton and damp cotton.

( 3 ) The reason for this is due to the indenter, measuring microscope, workbench three axis caused by different, as long as the instructions in accordance with the order adjusted separately on it.

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