Performance test of nodular cast iron plunger pump cylinder

(1) Surface hardness test

In order to make the depth of indentation less than the thickness of the layer and ensure the accuracy of the test results, the micro Vickers hardness is adopted. The selected test parameters are: 25 g load and 15 s holding time. Each sample is tested in three different areas, and the surface hardness of the sample is the average value after taking the average value of the measurement results.

(2) Microhardness test

The microhardness of the sample cross-section after nitrocarburizing is tested. The gradient of hardness distribution and the limit value of effective hardened layer depth are obtained from the edge of the sample section to the matrix direction, which can be combined to analyze the effective hardened layer depth of the sample. Before the start of the test, the standard sample should be used for calibration test, and the hardness test of the sample can be carried out after adjusting the load, so as to improve the accuracy of the test results. In this experiment, micro Vickers hardness was selected. The test parameters were load of 25 g (part of fragile edge load was 10 g) and holding time was 15 s. starting from the edge of 10 μ m, a point was made every 20 μ m inward, and a total of 14-15 points were tested.