
The effects of vibration frequency and amplitude on the microstructure and properties of ductile iron in lost foam casting were systematically studied. When the vibration frequency is 35Hz and the vibration amplitude is 4mm, the graphite spheroidization rate of vibration lost foam casting nodular cast iron is higher, the pearlite sheet spacing is smaller, and its tensile strength and elongation are larger.
When the vibration amplitude is 3mm and the vibration frequency is increased from 0Hz to 35Hz, the vibration increases the number of graphite balls and spheroidization rate per unit area, reduces the pearlite sheet spacing in the nodular cast iron, granulates some carbides in the alloy, and improves the tensile strength and elongation of the alloy, which reach 626.65mpa and 9.35% respectively. Compared with the EPC nodular cast iron without vibration, Increased by 4.82% and 42.53% respectively. This is because the application of vibration increases the undercooling of the alloy and the driving force in the solidification process. When the vibration frequency increases from 35Hz to 50Hz, although some carbides in nodular cast iron are still granulated, the tensile strength and ductility of nodular cast iron decrease due to the increase of pearlite sheet spacing and the increase of the number of graphite balls per unit area. When the vibration frequency continues to increase from 50Hz to 100Hz, due to the increase of pearlite sheet spacing, the number of graphite balls per unit area increases and the graphite morphology becomes worse, which increases the cleavage effect of graphite on the matrix and reduces the tensile strength and elongation of the alloy.
When the vibration frequency is 35Hz, increasing the amplitude of vibration lost foam casting can increase the force of vibration field on ductile iron melt. With the increase of amplitude, the number of graphite spheres per unit area increases gradually, and the spheroidization decreases first and then increases. The graphite spheroidization rate of nodular cast iron obtained under the condition of 3mm amplitude and 35Hz vibration frequency is low, and the distortion of nodular graphite is serious. When the amplitude is increased to 4mm and the vibration frequency is 35Hz, the nodularity of graphite in nodular cast iron is higher, the graphite morphology is better, the pearlite sheet spacing is smaller, and the tensile strength and elongation of nodular cast iron are larger, reaching 674.65mpa and 11.43% respectively. Compared with nodular cast iron without vibration, the tensile strength and elongation were increased by 16.76% and 74.24% respectively.