| Mn-Cu alloy is a kind of metal functional material with high damping performance,high strength,and plasticity,and has great development prospects in the field of vibration and noise reduction.Although a large amount of literature focuses on the improvement of the damping performance of cold deformed alloys by heat treatment,the damping mechanism of Mn-Cu alloys has also been understood by people,but people still lack understanding of how aging affects the properties of hot deformed alloys,especially The research on the mechanism related to thermal processing has yet to be elucidated.The hot deformation behavior of Mn-44Cu-1.5Al alloys was systematically studied by hot compression tests.The deformation temperature at 700?,750?,800?,850°C,strain rate at 0.01 s-1,0.1 s-1,1 s-1,10 s-1,and compressive volume at 50%.In addition,the hot-rolled deformation of the Mn-43Cu-1.5Al-1Sn alloy at 770?with 50%compression was performed to investigate the microstructure and the changes of the alloys at the aging temperatures of 380?,410?,430?,460?and aging time of 0.5 h,1 h,2 h,4 h.The main findings are as follows:1.During hot compression of the Mn-44Cu-1.5Al alloy,two mechanisms,continuous dynamic recrystallization(CDRX)and discontinuous dynamic recrystallization(DDRX),occur and CDRX is an auxiliary mechanism during hot deformation,DDRX dominates during hot deformation of the alloy.In the temperature range of 700?850?,increasing the deformation temperature would weaken the action of CDRX,enhance the grain growth effect during the DDRX,and increase the recrystallized grain size,while the peak rheological stress of the alloy would decrease.At strain rates 0.01?10 s-1 range,elevating the strain rate would enhance the action of CDRX and weaken the grain growth effect during the DDRX process,not only make recrystallized grain size decrease and rheological peak stress increase but also lead to the formation of necklace tissue in alloy tissue.2.Based on the hot compression test results of the Mn-44Cu-1.5Al alloys,two constitutive equations based on peak stress and strain compensated type were constructed,and the strain compensated constitutive equation had an absolute error mean of 4.42%and a correlation coefficient R2 of 0.992,indicating that the model can predict the rheological stress of the alloy more accurately.The hot working diagram of the alloy at strain 0.4?0.6 was established to determine the optimal process parameters for forming this alloy in combination with microstructure observation:deformation temperature 700?850?,strain rate 0.01?1 s-1.3.We found that the damping properties of the Mn-43Cu-1.5Al-1Sn alloys after hot rolling were poor,while after solid solution with the extension of aging time,the relative transformation amount and damping performance of martensite in the alloy first increase and then decrease.After solid solution,the damping performance was optimal at 410?for 1 h with an internal consumption value Q-1 of 0.024.The alloy after hot rolling shows good mechanical properties with 40.4%elongation and 433.2 MPa tensile strength.After solid solution,with the increase of aging time,the tensile strength of the alloy increases and the elongation decreases after aging at 410?for 4 h due to intermetallic compounds and?-Mn precipitates. |
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