Effect Of Ultrasonic Treatment On Microstructure And Properties Of High-silicon Nodular Cast Iron

High-silicon ductile iron is a new type of engineering material obtained by solid solution strengthening by increasing the silicon content.Solid solution strengthening is achieved by dissolving certain solute elements to form a solid solution so as to reinforce the material.High-silicon spheroidal graphite cast iron has excellent mechanical properties.Compared with ordinary spheroidal graphite cast iron and high-silicon spheroidal graphite cast iron,it has high tensile strength and high plasticity.It also has high yield strength and toughness,excellent machining performance,and high silicon ductile iron also Has a good high temperature,corrosion resistance characteristics,the current application at home and abroad more and more widely.Ultrasound is a kind of sound wave whose frequency is higher than 20 KHz.Its frequency is high,its power is large,and its energy is much larger than that of general sound waves.Ultrasonic fine-grain technology has been a late start,but it has quickly become a new bright spot in the field of fine-grained technology.Compared with traditional nucleating agent technology and temperature control processing technology,physical field addition technology such as ultrasonic fine-grained crystal can not only avoid the environment Contamination with the material itself can also achieve cleanliness,sustainable development,and can fully exploit the value of materials.In this paper,the ultrasonic fine grain technology was introduced into the preparation of high silicon nodular cast iron blanks.Ultrasonic treatment of the high silicon nodular cast iron melt was used to study the changes in the structure and properties,and the ultrasonic mechanism was studied.This subject introduces ultrasonic waves into the solidification process of high-silicon ductile iron melts,and experimentally studies the effect of ultrasonic waves on high-silicon ductile iron.During the experiment,it was completed by controlling two variables of ultrasonic processing time and power,and other conditions remained consistent.The set ultrasonic processing time is 10 S,20S,30 S,and the ultrasonic power is 100 W,200W,300 W,and the free combination of two or two crossover experiments is performed,and a set of untreated experiments are included,a total of 10 sets of experiments.Through the experiment,relevant index data were obtained,and two factors and three levels were used for orthogonal experiment analysis.At the same time,the metallurgical structure was analyzed according to the experimental results,and the mechanical properties of the high-silicon ductile iron were tested,including hardness and impact.Toughness,tensile strength,elongation and other aspects of the performance test,to obtain experimental data analysis of its laws,and analysis of high-silicon ductile iron performance change mechanism.Ultrasonic treatment can clearly refine the graphite balls in the as-cast microstructure of high-silicon ductile iron.The graphite balls are finer,rounder and more evenly distributed.When the ultrasonic power is 200 W and the processing time is 30 S,the finest effect is best and the graphite balls are spheroidized.The rate reached 93%,and the ball diameter level was 7;Ultrasonic treatment can significantly refine the matrix structure of high-silicon ductile iron,and the ferrite structure is more fine,dense and more evenly distributed.The refinement of high-silicon ductile iron is mainly due to the fact that the ultrasonic cavitation sound flow effect increases the degree of undercooling and increases the nucleation rate,resulting in good organization.The mechanical properties of the high-silicon ductile iron after ultrasonic treatment are improved,the tensile strength is increased by 59 MPa,the elongation is increased by 5.9%,and the impact toughness is increased by 27.7% compared to the untreated,mainly due to the ultrasonic treatment of the silicon element.The solution is more abundant,ferrite is strengthened,the ferrite structure is more uniform,the graphite spheres are refined,the number is increased,the distribution is more uniform,the strength and plasticity are improved,the hardness is also increased in a small range,the overall fluctuation is small,and the machining performance is excellent.The influence mechanism of ultrasonic on the microstructure and properties of high-silicon ductile iron was explored through experiments,so as to better optimize the production process of high-silicon ductile iron,further improve the performance of high-silicon ductile iron,and at the same time optimize the production technology of high-performance high-silicon ductile iron.