Simulation And Parameter Optimization Of Wire Feeding Nodularization Process For Molten Iron

Ductile iron has high mechanical properties such as strength,plasticity and toughness,etc which is widely used in industrial fields such as automobiles,wind power and high-speed railway,etc.The output of ductile iron in China has been increasing with years,and the quality of castings and the requirements of energy conservation and environmental protection have been continuously improved.The key that determines the quality of ductile iron is the nodularization process.Therefore,it is urgent to develop a more advanced production technology to spheroidizing molten iron.In this paper,the object of study was QT450-10.the molten iron was treated with the wire feeding nodularization and inoculation technology,the heat transfer characteristics and melt-blow characteristics of cored wire during the feeding process were researched with the simulation and experiments of the spheroidizing process.And the effects of wire feeding nodulization process parameters,the types and Mg content of cored wires on the Mg recovery,microstructure and mechanical properties of ductile iron were investigated.The results show that:Through manual insertion method and simulation,the theoretical prediction models of melting depth Hm and wire feeding speed V at different temperature ranges were obtained.When the temperature of the molten iron is constant,the melting depth of the cored wire is increasing as the wire feeding speed increases.When the wire feeding speed is constant,the melting depth of cored wire decreases as the temperature of the molten iron increases.The effect of magnesium content in the alloy-cored wire on the melting depth is not significant.Under the condition of wire feeding nodularization process,the nodularity of ductile iron is higher than 85%.the average temperature drop of molten iron is 42?,the wire feeding speed and spheroidizing temperature have a significant effect on the temperature drop of molten iron.When the spheroidization temperature is 1460?,the Mg recovery tends to increase as the wire feeding speed increases.When the spheroidization temperature is in the range of 1420??1560?,as the spheroidization temperature increases,Mg recovery shows a trend of increasing first and then decreasing.When the spheroidization temperature is 1520?,the mechanical properties of the alloy meet the requirements,the pearlite content in the alloy is less,the strength of the alloy is lower,but the plastic toughness is fineThe Mg recovery in the molten iron treated with nodularizing alloy-cored wire is slightly higher than that of the nodularizing mixture-cored wire.The nodularity of the molten iron treated with two types of nodularizing cored wire is above 85%,and the graphite size is 6?7 grade.Comparatively,the nodularity and graphite sphere diameter of the alloy treated with nodularizing mixture-cored wire is slightly lower than that of the alloy treated with nodularizing alloy-cored wire,while the counts of graphite sphere tends to increase lightly With the increase of Mg content in nodularizing cored wire,the Mg recovery,the nodularity and the counts of graphite sphere of ductile iron treated with two types of nodularizing cored wires is decrease,while the average diameter of graphite sphere tends to increase.The strength and hardness of ductile iron treated with nodularizing mixture-cored wires are higher than that of the ductile iron treated with nodularizing alloy-cored wire,but the plasticity and toughness is obviously lower.