Experimental scheme of split Hopkinson pressure bar for vermicular graphite cast iron.

Hopkinson pressure bar equipment can flexibly replace sleeves of different diameters, corresponding to incident rods and transmission rods of corresponding diameters. According to the sample size Φ 2mmx2mm, the rod with diameter of 4mm is selected, the material is 18Ni steel, the elastic modulus E is 200GPa, and the velocity of stress wave in the rod is 5000m/s. The technological process of sample production is as follows: the bar whose diameter is larger than 2mm is obtained by wire cutting, and the diameter is 2mm by a centerless grinder to ensure the surface quality and cylindricity. Finally, the sample whose length is greater than 2mm is obtained by wire cutting, and the sample is ground to 2mm on a surface grinder with a special grinding tool to ensure that the end face roughness is consistent with the length of each sample. Combined with Niu Jiahui M’s vermicular graphite cast iron cutting simulation results.

During the high temperature shock, the reheating furnace can not achieve good tightness, so the temperature in the furnace near the sample is measured in real time by thermocouple and kept at the preset temperature for 10 minutes before impact. In the experiment, each parameter was repeated for 3 times, and the middle group was taken as the result data. If the consistency of the results of three repeated shocks is not strong, the shocks will continue to be repeated until three sets of data with good consistency are obtained.