In 1991, Gong Jinying of Qiqihar Institute of light industry studied the relationship between the micro fracture morphology and mechanical properties of large section ductile iron container with different wall thickness. Fourteen tensile fracture specimens were selected from five different isothermal surfaces on the fan-shaped block for SEM observation. The ductile brittle transition mode of castings can be changed and the overall mechanical properties of castings can be improved by improving the spheroidization grade of graphite, fine graphite spheroidization and reducing the segregation of elements at grain boundaries. In 1992, the cooling effect of the forced cooling system for 20 ton ductile iron nuclear spent fuel container was studied. The results show that the solidification of castings can be accelerated by increasing the flow rate of cooling medium, and the cooling capacity of cooling system can be improved by selecting appropriate cooling medium and initial temperature of cooling medium and increasing the thickness of chill.
In 1994, Ding Linpu of Harbin University of science and technology studied the solidification characteristics and quality control measures of 20 ton nodular cast iron nuclear spent fuel container by using fan-shaped test block. Through reasonable selection of casting process and strict control of Mg, re, Si and other elements, the energy obtained from the final sector test block is shown in table 1-3. Both the strong plasticity and impact toughness meet the requirements of nodular iron nuclear spent fuel. On this basis, a 20 ton BQH 20 nodular iron nuclear spent fuel container has been successfully produced. The wall thickness of the container is as follows It weighs about 20 tons and has been produced 20 sets.
In 1996, Wang Jingqi m of Qiqihar No.1 Machine Tool Works studied the solidification characteristics of heavy section nodular iron castings, compared the solidification cooling characteristics of heavy section nodular iron castings under different cooling conditions, such as clay sand mold, carbon sand mold, graphite chill mold, cast iron chill mold, comprehensive air cooling and water cooling, and considered that graphite chill and hanging sand chill are the key to produce heavy section nodular iron castings The best cooling material, air cooling and water cooling are important measures to produce heavy thick wall nodular iron castings.
In 2009, Ma Xiaofeng of Harbin Institute of technology studied the microstructure and mechanical properties of heavy section ductile iron. He pointed out that the solidification rate obviously affected the number and size of graphite balls and the composition of matrix structure, but had little effect on the tensile strength. The composition of matrix structure had an impact on the fracture mode.
In 2010, Diao Xiaogang of Harbin University of technology adopted numerical simulation method to study the solidification characteristics of 100 ton ductile iron nuclear spent fuel container. The research shows that the solidification time of physical simulation test block can be less than 4 hours by adopting graphite chill + water cooling and other measures inside, and there will be no broken graphite in the structure.
In 2011, Zhou Xue of Harbin University of science and technology studied the solidification characteristics of ductile iron nuclear spent fuel container under different cooling conditions. According to the structural characteristics of ductile iron nuclear spent fuel container, the casting process was designed. The solidification process of ductile iron nuclear spent fuel container was simulated by using simulation software under four different processes: sand mold, sand mold chill, sand mold chill + central water cooling and sand mold chill + multi water pipe cooling. The characteristics of the four processes were analyzed, and the application of sand mold chill + multi water pipe cooling in ductile iron nuclear spent fuel container was pointed out The solidification process can be completed in two hours. The feasibility of the process is analyzed theoretically.
In 2012, Wang Liping of Harbin University of science and technology studied the production process and quality control measures of a 20 ton nodular cast spent fuel container with a wall thickness of 300 mm. The thickness of chill was determined by simulation software. The solidification characteristics of a 20 ton nodular cast spent fuel container were simulated by cubic test block to verify the water cooling effect. It was proposed that the cooling conditions had a decisive effect on eutectic solidification and solidification time The spheroidization can be kept in good condition within two hours.
In 2012, Guo Erjun, Harbin University of science and technology, aimed at developing ductile iron casting materials for nuclear spent fuel containers, studied the effect of forced cooling on the mechanical properties and fracture behavior of large section ductile iron. By studying the mechanical properties and fracture behavior of two cubes with the same size under different cooling conditions, he proposed that the extension of solidification time increased the abnormal graphite content of large section ductile iron The mechanical properties of castings are deteriorated and the fracture mode is changed.