Numerical Simulation And Process Analysis On 7050 Aluminum Planar Printing

As high strength aluminum alloy,Al-Zn-Mg-Cu is widely used in the field of aerospace and vehicle.Now,the commercial aluminum ingot is manly casted by traditional DC casting technology.To large size ingot,macrosegregation and internal cracking will influence the quality of ingot.Planar solidification can improve these problems.In the thesis,7050 aluminum alloy is used as experimental alloy.The thesis aims at improving planar solidification,exploring the experiments processing and simulating the process of planar solidification.In this thesis,a numerical model was built to describe the planar solidification by using the FLUENT software which is included in the Finite Element Analysis software.Based on the corresponding numerical simulation,the temperature field and flow field in the 600mm×600mm 7050 planar printing clad ingots were studied.The process of planar solidification consists of three stages:the stage of layering aluminum alloy,intermediate stage and the stable casting stage.The key processing parameters in every stage are researched to reveal their influence on the field of temperature and flow.In the first stage,the inlet moving velocity and cooling time were researched;in the second stage and third stage,casting velocity was researched.The processing parameters which match planar solidification have been obtained by numerical simulation.In first stage,when the inlet moving velocity is 20mm/s,the aluminum melt flow equably and the temperature gradient of transversal surface is small.When the cooling time is 30s,the temperature of ingot top surface arrives at 630 ?,at the same time,the temperature of ingot bottom surface arrives at 540 ?.In the second stage,when the casting velocity is 0.5mm/s,the molten pool is low.In the third stage,when the casting velocity is 0.5mm/s,the molten pool is low.The processing conditions of planar solidification were obtained:heat preservation material-graphite chock plug can better control the flux of aluminum than heat preservation chock plug;the T type chute with two bypass flow can divide molten aluminum more equably than the one with only one bypass flow;the strength of ingot is higher when the temperature of second casting is 620 ?.When the pure aluminum was casted by planar printing technology,temperature gradient on the transversal surface is low.The ingot was successfully casted by planar printing technology.What' more,620? was the best temperature of second casting.Based on the processing parameters determined by the simulation results,planar solidification ingot was carried out.Moreover,the ingot's surface quality was good and microstructure was uniform.