| Aluminum alloy has been widely used in aerospace industry for it's light weight,high strength and high corrosion resistance.The traditional processing method for Aluminum alloy is CNC machine,that is “Subtractive Manufacturing”,it not only causes the waste of base material,but also has many difficulties for the processing of the complex shape workpiece.Even if the processing conditions is acceptable,sometimes the program still can not be implemented for the processing cycle is too long.In this paper,2319 aluminum alloy is taken as the research object for “Arc Additive Manufacturing”,which can be used to a guidance in the future.In my reserch,2319 aluminum alloy welding wire with diameter of 1.6mm,5052 aluminum alloy substrate with length of 200 mm,width of 200 mm and height of 5mm were selected,CMT welder manufactured by Fronius company was used to carry out the arc additive manufacturing test.In this paper,I mainly fouces on the size prediction and porosity control.Firstly,with the method of secondary universal rotary combination design,the wire feeding speed(2.5-7mm/min),welding speed(500-1800mm/min)and protective gas flow(15-20 L /min)were carried out in single-layer and single-psaa additive test,The length is 130 mm,and 20 samples were made in total to predict the width and height.Then interlayer waiting time(40-180s)was also taked into consideration,through four factors half implementation design to carry out multi-layers and single-pass reciprocating additive test,each sample was 20 layres,and the length is aslo 130 mm,20 samples were made to predict the total width and height.The rule of single and interactive influence of additive parameters on size is also analyzed.As the deformation of substrate was found to be serious during the preliminary additive test,so the temperature field and stress field of the substrate in cooling stage were simulated in ansys.The maximum deformation was analyzed,then the fixed way of the substrate was changed,which effectively inhibited the deformation.Finally,through the control variable method,analyse the number,size and distribution of prosprity under the influence of wire feeding speed,welding speed and protection gas flow,then the distribution of micro-hydrogen pores and the source of hydrogen were briefly analyzed.According to the research,the average prediction errors of the width and height for first layer are 0.31 mm and 0.26 mm,and the average prediction errors of the total width and height of the multi-layers and single-pass are 0.27 mm and 1.1mm,The prediction results are good.Among all the parameters,wire feeding speed has a positive effect on the width and height of the additive process,while welding speed has a negative effect on the width and height of the additive process,but wire feeding speed has a more obvious effect on the size than welding speed.The influence of protective gas flow on the width was parabola with downward opening,and the interlayer waiting time had a negative influence on the width.The influence of protective gas and interlayer waiting time on the height was exactly opposite to its influence on the width.From the simulation results of temperature field and stress field,it can be seen that the maximum deformation value is 3.299 mm after20 layers of additive process,In order to ensure the precision of molding and dimension measurement,it is necessary to change the fixation way.It was found in the study of porosity problem,increase the wire feeding speed will increase the number and diameter of porosities,when the welding speed increases,the number of porosities will decrease obviously,when the protection gas flow is enough to protect the additive process,adjusting the protection gas flow in a certain range does not have a great influence on the porosities.Under the condition of satisfying the technological requirements,the porosities can be suppressed by combining low wire feeding speed with high welding speed. |
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