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Factors Affecting The Accuracy Of Portable Hardness Testers
Oct 16, 2018

Factors affecting the accuracy of portable hardness testers


Let's talk about the factors that affect the accuracy of portable hardness testers.


1. Errors caused by data conversion


The error of conversion of Richter hardness to other hardness includes two aspects: the non-destructive testing resource network is the measurement error of the Leeb hardness itself, which involves the dispersion of the test according to the method and the measurement of multiple portable hardness testers of the same type. error. 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, the error caused by special materials


The conversion table stored in the hardness tester may deviate from the following steel grades:


All austenitic steel heat-resistant tool steels and Leysite chrome steel (tool steel) hard materials cause an increase in the modulus of elasticity, resulting in a lower L value. 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. Error 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. Influence of material elasticity and plasticity


In addition to the hardness and strength, the Richter value is more related to the elastic modulus. The hardness value is a 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 larger L value.


5. Error caused by hot rolling direction


When the workpiece to be tested is formed by the hot rolling process, if the test direction is consistent with the rolling direction, the test value is low due to the large elastic modulus E, so the test direction should be perpendicular to the hot rolling direction.


6, the impact of sample weight, roughness, thickness


7, the test piece magnetic should be less than 300 Gauss