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金属布氏硬度试验是用一定直径的钢球或硬质合金球,以相应的试验力压入金属表面,经规定保持时间后,卸除试验力来测量压痕直径。压痕直径的测量是至关重要的。目前,在一些自动硬度计或在大批量试验时,常用百分表测量压痕深度,以提高试验速度。但由于试样卸荷后,压痕深度的弹性恢复和钢球压头的弹性扁缩,不仅对测量压痕直径有较大误差,而对测量压痕深度误差更大。所以用百分表测量的压痕深度值一般是不准确的,只有精确地测量出压头在保荷过程中下移的最大位移量,才能测出真
Metal Brinell hardness test is the use of a certain diameter of steel balls or cemented carbide ball, the corresponding test force into the metal surface, the provisions of the holding time, unloading test force to measure the indentation diameter. Measurement of indentation diameter is crucial. At present, some automatic hardness tester or in high-volume test, commonly used dial gauge measuring indentation depth, in order to improve the test speed. However, due to the unloading of the specimen, the elastic recovery of the indentation depth and the elastic shrinkage of the steel ball indenter not only have a great error in measuring the diameter of the indentation, but also make greater errors in the depth of the indentation. Therefore, the depth of indentation measured with a dial indicator is generally not accurate, only accurate measurement of the pressure head in the process of charging down the maximum displacement, in order to measure the true