| 5B06 aluminum alloy belongs to aluminum-magnesium antirust aluminum alloy,has higher strength and good corrosion resistance,is mainly used in the manufacture of carrier rocket tank,satellite tank.In the carrier rocket tank,the inner layer of the screen film accessory,which is composed of the vortex eliminator and the energy eliminator,needs to meet the requirements of different propellant types,sizes and pressurization methods.The traditional processing methods are riveting and welding.The pump body used in the booster transport system of carrier rocket needs to be manufactured as a whole.The traditional mold casting method has a long cycle and high cost,and the additive manufacturing can solve these problems well.In the process of aluminum alloy additive,the porosity is the main reason that affects the mechanical properties,this paper aimed at this problem,using plasma arc as forming equipment additive manufacturing 5B06 aluminum alloy,observe the characteristics of aluminum alloy internal porosity,analysis of the formation mechanism of aluminum alloy internal porosity.The influence of plasma arc additive manufacturing parameters on the porosity of 5B06 aluminum alloy was studied by single factor experiment.Under the condition of good macroscopic morphology,samples with low porosity were obtained through process control.On this basis,stomatal inhibition experiments were carried out to study the influence of different inhibition methods on stomata.The samples were prepared by different methods with lower porosity,and the changes of mechanical properties after porosity inhibition were compared by tensile test.The main research contents and conclusions are as follows:1.The characteristics and formation mechanism of typical pores in aluminum alloy additive manufacturing samples were studied.Based on the Image Pro software,the size and number of stomata were counted.The pore size and pore distribution of the sample were regular and round.There were large pores in the bottom and top layers,and the number of pores in the bottom layer was more than that in other layers.The pores are mainly distributed at the junctions between layers,and the size of the pores is smaller than that in the sediments.Through analyzing the formation process of pores,it is found that the adhesion surface and nucleation point provided by the deposited surface for pores,the existence time of molten pool,the temperature of molten pool and arc force are the main factors affecting the characteristics of pores and their distribution.2.Under the guidance of the formation mechanism of stomatal defects,a single factor experiment was designed to study the influence rule of process parameters on stomatal defects.With the increase of welding current,the porosity increases constantly.As the ratio of wire feeding speed,welding speed,ion gas flow rate and cathode cleaning time increases,the change of porosity is basically the same,showing a trend of decreasing first and then increasing.3.The forming process with good morphology and low porosity was determined.The effects of different methods on the suppression of porosity in aluminum alloy additive were studied by means of interlayer remelting,preheating before welding and interlayer forging,and the tensile properties were tested.After using the above three methods,the porosity decreases to a certain extent,and the tensile properties of the samples are improved.Among them,the interlayer forging has the most significant inhibition effect,the porosity is 0.28%,which decreases by 67.44%,and the tensile strength can reach 376.83 MPa,which increases by about 21.11%.Compared with 5B06 aluminum alloy in O state and H112 state,it is increased by 19.62%. |
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