| ZL205A alloy has been widely used in the aerospace industry due to its low density and good comprehensive mechanical properties.However,ZL205 A alloy tends to paste-like solidification,coarse solidification structure,and easy to produce defects such as shrinkage and shrinkage.The vacuum differential pressure grading and pressing technology provides a strong feeding force in the solidification stage,and can obtain a dense structure of the casting,and the electromagnetic stirring technology can also achieve the effect of grain refinement.Therefore,combining electromagnetic stirring technology with vacuum differential pressure grading and pressing,it is of theoretical significance to study the microstructure and mechanical properties of alternating magnetic field and vacuum differential pressure graded pressure casting ZL205 A alloy.In this paper,the magnetic field strength,the grading pressure difference and the grading pressure time are studied.The microstructure and mechanical properties of the alternating magnetic field synergistic vacuum differential pressure graded pressure casting ZL205 A alloy are studied.The solidification shrinkage and fineness of the alloy under the synergistic field are analyzed.Mechanism.The results show that under the condition of constant pressing time,when the magnetic field strength is less than 200 GS,the alternating magnetic field and the grading pressure will inhibit the grain growth of ZL205 A alloy and enhance the lock-in ability of the molten metal.The density and mechanical properties are improved.When the magnetic field strength is greater than 200 GS,the alternating magnetic field and the grading pressure difference will promote the grain growth of ZL205 A alloy,and the density and mechanical properties of the alloy will decrease.Under the optimal process casting conditions of magnetic field strength of 200 GS and graded pressure difference of130 KPa,the grain size of ZL205 A alloy is the smallest,and the density and mechanical properties of the alloy reach a peak.Compared with single-stage pressure casting samples,microstructure and mechanics Performance is effectively improved.By studying the microstructure of different diameter samples under the action of magnetic field and staged pressure synergy field,it is found that the synergistic field effect has little effect on the microstructure of samples with different diameters.Thechilling effect of the mold has a more significant influence on the sample structure.The synergistic field has a certain influence on the density of samples of different diameters,and the effect of the graded pressure field on the density of the sample is more significant than that of the magnetic field.In addition,the effect of graded pressurization time on the microstructure and properties of ZL205 A alloy under the action of synergistic field was studied.The best graded pressurization time for a sample with a diameter of 30 mm was found to be 110 s.Therefore,under reasonable process parameters,magnetic field stirring technology and vacuum differential pressure graded pressure casting technology will significantly improve the microstructure of ZL205 A alloy,and provide theoretical basis and technical support for aluminum alloy precision castings with better production performance. |
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