Measurement of mechanical properties and machinability of gray cast iron and observation of microstructure

The specific test process is as follows:

1.Use WAW-Y500 universal material testing machine to measure the tensile strength of the sample, and the tensile sample shall be prepared according to GB / T228-2002. Tensile strength: take the average value of four tensile specimens;

2.After the tensile strength test of the tensile sample, select a sample closest to its average value from the four materials, cut a part horizontally at the fracture to prepare the metallographic sample, and use Olympus pmg3 metallographic microscope with siscas. V8.0 metallographic image analysis software to analyze the graphite morphology and content, matrix structure The distribution and content of pearlite were analyzed. The spacing of pearlite sheets and the size of carbide were analyzed by JSM-5610LV scanning electron microscope;

3.Use hb-3000 Brinell hardness tester to measure the hardness at different thicknesses of the step sample, make five points diagonally on each thickness side of the step sample, and obtain the average value of one thickness side, so as to obtain the average hardness of the step sample; Calculate the hardness difference between the thickest surface and the thinnest surface △ HB = hbmax hbmin to obtain the section sensitivity;

4.Use mh-3 microhardness tester (load 200 g, hold for 10 s) to measure the microhardness of metallographic sample matrix. Measure ten points on each sample, and then calculate the average value to obtain the microhardness.

5.Turn the cylindrical cutting test bar on the CA6140 horizontal lathe. The force on the cylindrical cutting test bar is transmitted to the strain gauge connected with it through the octagonal ring, and the obtained strain is converted into the cutting force for cutting the sample through the calibration curve.