| 5083 aluminum alloy which has excellent weldability,high corrosion resistance and good deformation is widely used in aerospace,automotive,shipbuilding and construction industry.However,during deformation process it exhibit Portevin-Le Chatelier effect(PLC).PLC effect has adverse influence on formability of 5083 aluminum alloy and gives the materials undesired markings on the surface.Now,The general consensus explains the origin of the PLC effect as dynamic strain aging(DSA).It is associated with conditions when point defects can diffuse towards mobile dislocations and temporarily arrest them.In the past,theresearch on the PLC effect of 5083 aluminum alloy mainly focused on the deformation temperature and strain rate,the results showed that the interaction between Mg solid solution and motion dislocation is the basic reason for PLC effect on 5083 aluminum alloy.However,the there are few reports about the degree of Mg in solution and existing form in 5083 aluminum alloy.In this study,we attempt to control the temperature of heat treatment and cooling-down method to change the Mg content in solid solution of 5083 aluminum alloy,at the same time,the quantity,size and distribution of β phase in 5083 aluminum alloy have been changed.Tensile tests are performed on these samples for a wide range of strain rates to explore the influence of Mg solid concentration and β phase on PLC effect.Furthermore,we investigate the mechanism of solid concentration and β phase Interact with moving dislocation.Following is the main studying conclusions:1.The size of grain,size,number,distribution of excess crystalline phase and dispersion phase are not significantly affected by the temperature of anneal and solution in 5083 aluminum alloy.When the temperature of anneal rise,β phase in alloy change with increasing in size and reducing in dispersion.In quenched 5083 plate,the Mg atoms mainly existed in the matrix and become solid concentration.2.At early stage of plastic deformation,annealing 5083 aluminum alloy shows yield elongation clearly.With the increase of annealing temperature,the yield strength and the tensile strength of the alloy decrease.When the temperature of quenching is under 350℃,the quenched 5083 aluminum alloy shows yield elongation at the early stage of plastic deformation,the yield strength decreases with increasing the temperature of solid solution treated,but the the tensile strength has little effect with it.3.When rise strain rate,there is little change in the yield strength of annealed and quenched 5083 aluminum alloy,but the tensile strength reduces significantly.So we know during plastic deformation annealed and quenched 5083 aluminum alloy appeared negative strain rate sensitivity.4.PLC effect occurs in annealed and quenched 5083 aluminum alloy when the strain rate is between 1×10-5s-1～1×10-2s-1.With increase of strain rate,magnitude of serration,waiting time and fall time decrease in annealed and quenched 5083 aluminum.And the critical strain of PLC effect decrease quickly when increase the strain rate,while the strain rate is beyond1×10-3s-1,the critical strain of PLC effect will increase slowly when we rise strain rate.5 Under a low strain rate(1×10-4s-1、1x10-5S-1),when PLC effect occurs,the stress decrease abruptly in annealed and quenched 5083 aluminum alloy,which implied some dislocations were unpinned.Under a high strain rate(1x10-2s-1、1×10-3s-1),when PLC effect occurs,the stress increase abruptly in annealed and quenched 5083 aluminum alloy,which implied some dislocations were pinned.6.When the strain rate is under 1×10-4s-1,the critical strain of PLC effect in annealing alloy was less than the critical strain of PLC effect in quenching alloy;When the strain rate is beyond 1x10-3s-1,the critical strain of PLC effect in annealing alloy was more than the critical strain of PLC effect in quenching alloy.But difference of annealing alloy and quenching alloy has no obvious difference between the magnitude of serration,waiting time and fall time. |
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