- Errors caused by data conversion
The error when converting the Leeb hardness to other hardnesses 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 measurement error of multiple Leeb hardness testers of the same type. On the other hand, there is the error of comparing the hardness measured by different hardness test methods, which is due to the fact that there is no clear physical relationship between one of the various hardness test methods, and is affected by the unreliable measurement in mutual comparison.
- Errors caused by special materials
The conversion table stored in the hardness tester may deviate from the following steel grades:
All austenitic steels
Heat-resistant tool steels and ledeburite chrome steels (tool steels) are hard materials that cause an increase in the elastic modulus, resulting in a lower L value. Such steels should be tested in cross section
Local cooling hardening will cause high L value
Magnetic steel will have a low L value due to the influence of the magnetic field.
The surface hardened steel has a soft matrix, which will lower the L value. When the hardened layer is larger than 0.8mm (0.2mm for the C-type impact device), the L value will not be affected.
- Error in gear detection
In general, due to the small tooth surface, the test error is relatively large. In this regard, the user can design corresponding tooling according to the situation, which will help reduce the error.
- The influence of material elasticity and plasticity
In addition to the hardness and strength, the Leeb value is also related to the elastic modulus. The hardness value is a characteristic parameter of the hardness and plasticity of the material, because the components of the two must be determined together.
In the elastic part, it is obviously affected by the E modulus. In this regard, when the static hardness of the material is the same, but the E value is different, the material with a lower E value has a larger L value.
- Error caused by hot rolling direction
When the tested workpiece is formed by hot rolling process, if the test direction is consistent with the rolling direction, the test value will be low 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 cylindrical section, it is better to test in the radial direction. (Generally, the hot rolling direction of the cylinder is the axial direction).
- The influence of sample weight, roughness and thickness
- The magnetism of the test piece should be less than 300 Gauss
- The influence of other factors
When measuring the hardness of the pipe fittings, pay attention to: the pipe fittings should be firmly supported, the test point should be close to the support point and parallel to the support force, and the pipe wall should be thin, and an appropriate core should be placed in the pipe.
The above Factors which Affecting Test Accuracy, Error and Repeatability of Leeb Hardness Tester should be considered.
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