Effect of sample quality
The surface roughness, curvature and thickness of the sample will all affect the measurement error. Because the surface roughness has a great influence on the size of the indentation measured, generally, the rougher the surface, the lower the measured hardness value of the sample. If the sample thickness is small enough, the hardness value measured by the durometer will also be low. At this time, the measured value needs to be corrected.
The impact of the measuring device
The precision of the hardness tester and the hardness tester's operation measurement are correct enough. All of them will cause great errors in the measurement result. Therefore, it must use the Brinell hardness tester that has been qualified by the measurement department, has not exceeded the verification cycle and is not damaged by itself. Brinell hardness measurement. When the Brinell hardness tester must be sent to the metrological verification department for periodical verification operations, it should slowly and steadily press the indenter onto the sample surface.
Indentation diameter measurement effect
According to the formula derivation, it can be concluded that the relative error of the hardness value is the relative error of the indentation measurement. According to the calculation formula of Brinell hardness, the indentation measurement error has a great influence on the hardness value error, so the indentation measurement error is the main source of error. If the indentation diameter measurement value is too large, the calculated hardness value will be biased. Small, on the contrary, the hardness value will be higher than the value. In order to reduce the error, the accuracy of the microscope for measuring the diameter of the indentation must be ensured, and secondly, when the condition permits, a larger load force and a larger steel ball should be used for measurement. The larger the diameter of the trace, the smaller the relative error
Impact of ball head
Brinell hardness of steel ball head diameter increases, its hardness value decreases, and vice versa If the steel ball used is small steel, when the load is applied, the steel ball itself will also have elastic and plastic deformation, and its low Hardness errors have a greater impact and must therefore be measured under standard head diameter conditions.
Effect of test load force
If the test load force increases, the measured hardness will decrease, otherwise, the hardness value will increase and the Brinell hardness will change with the load force. The compliance of the Brinell hardness test depends on the accuracy of the weight, the accuracy of the applied load device and the correctness of the applied load force. Practice shows that the relative error of the hardness value is related to the relative error of the load. Therefore, to increase the hardness measurement accuracy, it is necessary to reduce the load error, for example, the operator operates according to the basic principle of Brinell hardness, and regularly checks and calibrates the Brinell hardness tester, and tests under the standard conditions of the Brinell hardness test.
Effect of temperature changes on the sample
Before measuring the hardness value of the sample, the measurement personnel must measure the ambient temperature. If the ambient temperature deviates from the standard ITI value, a temperature correction must be made to the measured hardness value to reduce the error. Changes in temperature can cause changes in the structure of the material. Brinell hardness tests are strongly influenced by the material's microstructure. When the temperature of the sample increases, the Brinell hardness value decreases. Otherwise, the Brinell hardness value increases. Therefore, the temperature of the sample must be consistent with the temperature of the laboratory. In the actual test work, it may be possible to control the ambient temperature and the sample temperature within the required standard test temperature conditions. The standard of the Brinell hardness test method is used to measure the Brinell hardness of the material surface.