Analysis of Factors Affecting Measurement Accuracy of Leeb Hardness Tester


First, the measuring range of the Leeb hardness tester
According to the principle of Richter, as long as the material has a certain rigidity and can form a rebound, the accurate value of the hardness can be measured. However, many materials have no corresponding conversion relationship with the hardness of other systems, so the Leeb hardness tester is currently only installed. Conversion table of nine materials. The specific materials are as follows: steel and cast steel, alloy tool steel, gray cast iron, ductile iron, cast aluminum alloy, copper-zinc alloy, copper-tin alloy, pure copper, stainless copper.
For samples of special materials, the user can use the fitting curve software provided by the company to make a special conversion table. In actual production, the metal materials used are various. Because the Leeb hardness tester is sensitive to the processing method of the material and the alloying element composition of the material, the hardness conversion table stored in the Leeb hardness tester chip cannot meet the needs of the user. In the test, the user can use the fitting software to make his own special hardness conversion table.
Analysis of Factors Affecting Measurement Accuracy of Leeb Hardness Tester

Second, factors affecting the accuracy of the Leeb hardness tester
1. Errors in data conversion The error in conversion of Richter hardness to other hardness includes two aspects: one is the measurement error of the Leeb hardness itself, which involves the dispersion of the test according to the method and the multiple models of the same type. The measurement error of the hardness tester. On the other hand, it is the error caused by the hardness measured by different hardness test methods. This is because there is no clear physical relationship between one of the various hardness test methods, and it is affected by the unreliable measurement in the comparison.
2. Errors caused by special materials The conversion table stored in the hardness tester may have deviations for the following steel grades: All austenitic steel heat-resistant tool steels and Leysite chrome steel (tool steels) hard materials may cause elasticity. The modulus is increased so that the L value is low. This kind of steel should be tested on the cross section. Local cooling hardening will cause the L value to be high. The magnetic steel will have a low L value due to the influence of the magnetic field. Surface hardened steel, soft matrix, will lower the L value. When the hardened layer is larger than 0.8mm (0.2mm for C-type impact device), the L value will not be affected.
3. Errors in gear detection Under normal circumstances, because the tooth surface is small, the test error is relatively large. For this, the user can design the corresponding tooling according to the situation, which will help reduce the error.
4, the influence of material elasticity, plasticity In addition to hardness and strength, the value of the Richter is more related to the elastic modulus, the hardness value is the characteristic parameter of the hardness and plasticity of the material, because the composition of the two must be jointly determined. In the elastic part, firstly, it is obviously affected by the E modulus. In this respect, when the static hardness of the material is the same, and the E value is different, the material with a low E value has a large L value. 5. The error caused by the hot rolling direction is measured. When the workpiece is hot-rolled, if the test direction is consistent with the rolling direction, the test value will be lower due to the large elastic modulus E, so the test direction should be perpendicular to the hot rolling direction. For example, when measuring the hardness of a cylindrical section, it should be tested in the radial direction. (General cylindrical hot rolling direction is axial).
6. The magnetic properties of the test piece should be less than 300 Gauss. 7. The influence of other factors should be noted when measuring the hardness of the pipe fittings: the pipe fittings should be firmly supported. The test point should be close to the support point and parallel to the supporting force. The pipe wall is thin and the appropriate core is placed in the pipe. .

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