(1) Sample preparation. Using sheet tensile samples, first cut a sheet with a thickness of 2 mm from the middle of the cylindrical ductile iron casting test bar by wire cutting machine (considering the solidification sequence and solidification characteristics of ductile iron casting, the middle structure can better represent the overall performance of the whole test bar), and then cut into tensile samples according to the size shown in the figure, and use 80#, 200# The 400 # sandpaper will polish the wire cutting marks on the surface of the ductile iron casting sample smoothly to prevent the existence of small dents on the surface of the ductile iron casting sample, reduce the accuracy of the tensile test and make the tensile results produce errors.
(2) Tensile test. Wdw-200 micro control electronic universal testing machine is used for tensile test. Before the test, the width and thickness of the working part of each tensile ductile iron casting sample are measured with vernier caliper, and the average value is measured for many times to reduce the error and determine the cross-sectional area of the tensile ductile iron casting sample. Clamp both ends of the ductile iron casting sample on the tensile testing machine for tensile test, and set the tensile rate to 0.06 mm / min. After the ductile iron casting sample is broken, the original data is derived, the tensile curve is drawn by using the origin drawing software, and the yield strength, tensile strength and elongation of the ductile iron casting sample are calculated.