Friction stir extrusion(FSE)is known as an innovative manufacturing technology that makes it possible to directly produce wire via consolidation and extrusion of metal chips or solid billets.In this study,wire samples...Friction stir extrusion(FSE)is known as an innovative manufacturing technology that makes it possible to directly produce wire via consolidation and extrusion of metal chips or solid billets.In this study,wire samples were produced using aluminum alloy AA7022 machining chips by the use of the FSE.To this end,the microstructures and mechanical properties of the base material(BM)and the extruded samples were investigated.The corrosion resistance of the given samples was also determined using potentiodynamic polarization technique.The results showed that the samples manufactured at higher rotational speeds possessed good surface quality,the process temperature and the grain size similarly increased following the rise in rotational speed,and the mechanical properties consequently decreased.Using the FSE led to crystallite refinement,increase in volume fraction of grain boundaries,as well as re-distribution of precipitates affecting corrosion resistance.Furthermore,the findings of the corrosion tests revealed that the produced samples by the FSE had adequate corrosion resistance and the growth in die rotation rate augmented current density and subsequently reduced corrosion resistance.展开更多
The effect of temperatures and time of post-process aging on the microstructure,mechanical properties and wear behavior of friction stir processed 7075 Al alloy was investigated,using optical microscopy（OM）,scanning...The effect of temperatures and time of post-process aging on the microstructure,mechanical properties and wear behavior of friction stir processed 7075 Al alloy was investigated,using optical microscopy（OM）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM） and Vickers microhardness tester.The results indicate that homogeneous,equiaxed and fine recrystallized microstructure is obtained with the grain size of 4-5 μm.The hardness value increases up to 30% and 80% in the stir zone and the base material,respectively.Based on the TEM observations,it is concluded that the improved properties following the duplex friction stir-aging process can be attributed to the very fine precipitates.Comparing the single and double aging conditions,the hardness of single aging sample is higher than that of double aging one which can be attributed to the high fraction of very fine spheroidal precipitate in single aging sample.The wear rate is reduced by the aging of Al alloy and a more decrease is achieved after the aging of FSPed sample.展开更多
文摘Friction stir extrusion(FSE)is known as an innovative manufacturing technology that makes it possible to directly produce wire via consolidation and extrusion of metal chips or solid billets.In this study,wire samples were produced using aluminum alloy AA7022 machining chips by the use of the FSE.To this end,the microstructures and mechanical properties of the base material(BM)and the extruded samples were investigated.The corrosion resistance of the given samples was also determined using potentiodynamic polarization technique.The results showed that the samples manufactured at higher rotational speeds possessed good surface quality,the process temperature and the grain size similarly increased following the rise in rotational speed,and the mechanical properties consequently decreased.Using the FSE led to crystallite refinement,increase in volume fraction of grain boundaries,as well as re-distribution of precipitates affecting corrosion resistance.Furthermore,the findings of the corrosion tests revealed that the produced samples by the FSE had adequate corrosion resistance and the growth in die rotation rate augmented current density and subsequently reduced corrosion resistance.
文摘The effect of temperatures and time of post-process aging on the microstructure,mechanical properties and wear behavior of friction stir processed 7075 Al alloy was investigated,using optical microscopy（OM）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM） and Vickers microhardness tester.The results indicate that homogeneous,equiaxed and fine recrystallized microstructure is obtained with the grain size of 4-5 μm.The hardness value increases up to 30% and 80% in the stir zone and the base material,respectively.Based on the TEM observations,it is concluded that the improved properties following the duplex friction stir-aging process can be attributed to the very fine precipitates.Comparing the single and double aging conditions,the hardness of single aging sample is higher than that of double aging one which can be attributed to the high fraction of very fine spheroidal precipitate in single aging sample.The wear rate is reduced by the aging of Al alloy and a more decrease is achieved after the aging of FSPed sample.
