| Commercial aluminum alloys have excellent corrosion resistance,easy processing,weldability and excellent mechanical properties.As engineering materials,it is widely used in aerospace,rail transportation,automobile manufacturing and other fields.In recent years,more and more requirements have been placed on the vibration and noise reduction of equipment and materials in the engineering field.The damping performance of alloys has gradually attracted people’s attention.Unfortunately,commercial aluminum alloys are generally considered to be low-damping alloys,which greatly limits the special applications of commercial aluminum alloy materials in certain engineering fields.Therefore,improving the damping capacity of aluminum alloys from material design and preparation has become an urgent need in engineering applications.Friction stir processing(FSP)is a process for modifying materials and preparing composite materials.It can homogenize the microstructure,refine the grains,and help to improve the damping properties of the alloy.This article chooses 4032,5086,6082 and 7075 four kinds of commercial aluminum alloy as the research object,adopts friction stir processing technology(Friction stir processing,FSP)to process four different brands of commercial aluminum alloy.Effectively improve the damping properties of aluminum alloys.At the same time,the influence of different FSP process parameters on the microstructure,mechanical properties and damping behavior of aluminum alloys is also studied,which provides experimental basis for the preparation of aluminum alloys with high damping properties.The results of the study showed that the fine-grained Si particles of 4032 aluminum alloy were uniformly distributed in the aluminum matrix after FSP treatment.The aluminum grains are refined,and the grain refinement improves the sliding ability of grain boundaries.Low-speed(300rpm)FSP samples have the best tensile strength,elongation and damping properties.After 5086 aluminum alloy was treated with FSP,the coarse rolled grains were obviously refined,and fine equiaxed grains were formed in the processing area.The FSP sample exhibits low yield strength,high elongation and almost the same tensile strength as the parent metal(BM).After the damping performance test,the FSP-400(the stirring rotation speed is 400rpm)sample with fine grain structure has the best damping performance.With the increase of the stirring rotation speed,the damping performance of the FSP sample decreases.The 6082 aluminum alloy aging treatment experiment found that when the temperature is less than 135℃,the aluminum alloy in underaged condition has the highest damping performance.When the temperature is higher than 260℃,the peak aging state has the highest damping performance.After FSP was performed on 6082 aluminum alloy,it was found that the machining speed of 200 rpm aluminum alloy sample had an ultrafine grain structure,With an average grain size of 0.8 μm,the high-angle grain boundary volume fraction reaches 90%,and the second phase undergoes a metastable β " phase transformation to a stable β′ phase,which has high temperature and high damping capacity.The metastable β" phase disappears in aluminum alloy at a high rotation speed of 1500 rpm.7075 aluminum alloy undergoes a complete dynamic recrystallization process after FSP,forming a fine uniform equiaxed grain structure,and the grain size increases with the increase of the stirring rotation speed.When the speed of the stirring head is 400 rpm and 1500 rpm respectively.The precipitation and dissolution of η phase occurred separately.The damping performance of 7075 aluminum alloy at low rotation speed was obviously higher than that of the parent metal. |
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