Three-dimensional Mathematical Shape And Heat Transfer Model Of Spray-formed Billet

Spray forming is an advanced technology that is used to produce avariety of high–performance materials with the characteristics of rapidsolidification. By properly controlling of spray forming parameters, it ispossible to fabricate near–net–shaped preforms.The metallurgical quality of a spray-formed deposit is alwaysdetermined by the shape evolution, solidification and cooling behavior ofthe deposit. However, involving a variety of process parameters which areinfluenced by each other, these processes are too complicated to studythrough experimental method. In addition to experimental investigation,numerical simulation has been used as a method to analysis the shapeevolution and heat transfer of the deposit, which can reduce theexperimental trials and costs, as well as shortening the research period.In this paper, a three-dimensional (3D) mathematical shape evolutionmodel of rod-billet based on MATLAB during spray forming has beenestablished. And the shape evolutions of different spray forming processeswere simulated, such as constraint-atomization, single and twin scanningspray forming. The transient shape modeling has been validated bynumerical algorithms and experimental investigation, and has proved thatthe simulated billet profiles are in good agreement with the experimentaldata.Based on the3D shape model, the effect of spray forming parametersusing different spray forming processes were analyzed. According to theobtained simulation results during constraint-atomization spray forming,the most dominant parameters affecting the shape evolution of deposit arethe spray distribution parameters, withdrawal velocity, and initial eccentric distance. In single-scanning or twin-scanning spray forming, the periodicalmovement between the scanning of the atomizer and the rotation of thesubstrate also plays an important role in the growth of the deposits.Coupling with the3D shape model, a three-dimensional heat transfermodel of deposit which describes the spray forming process moreaccurately and gives more details about the thermal profiles of the deposithas been developed. The thermal history of a billet under the differentconditions of droplet temperature was also calculate based on this model.And the results shows that the enthalpy input from the spray of droplets tothe preform are found to be the dominant influencing factors.