Friction stir processing (FSP) is a solid-state modification method to process the surface of metals. In this process, due to rotation and traverse motions of a non-consumable tool, metal surface microstructure is ref...Friction stir processing (FSP) is a solid-state modification method to process the surface of metals. In this process, due to rotation and traverse motions of a non-consumable tool, metal surface microstructure is refined and its mechanical characteristics are improved. Different methods have been applied to improving the efficiency of FSP. In this research, a new method entitled friction stir vibration processing (FSVP) was presented to enhance the efficiency of FSP. In this method, metal workpiece was vibrated normal to processing line during FSP. Microstructure and mechanical properties including hardness, ultimate tensile strength (UTS) and elongation of Al5052 alloy specimens processed using FSP and FSVP methods were analyzed and compared. The results showed that grain size decreased by about 33% as vibration was applied. It was also observed that ultimate tensile strength as well as hardness increased by about 7% as FSVP was applied. This was related to the enhanced straining of metal surface material as vibration was applied. The increase in straining results in the increase of dislocation density. It leads to more development of high angle grain boundaries due to dynamic recrystallization. The results also showed that UTS and elongation of FSV processed specimens increased as vibration frequency increased.展开更多
The effect of friction stir processing(FSP)at different rotation speeds(400,630,800,and 1000 r/min)and traverse speeds(25 and 50 mm/min)on the tribological properties of a Si particle reinforced Zn−40Al−2Cu-based in-s...The effect of friction stir processing(FSP)at different rotation speeds(400,630,800,and 1000 r/min)and traverse speeds(25 and 50 mm/min)on the tribological properties of a Si particle reinforced Zn−40Al−2Cu-based in-situ composite was investigated.After preliminary optimization,800 r/min and 25 mm/min were selected as optimum FSP parameters.According to the results,multi-pass FSP improved the tribological properties.For instance,at an applied pressure of 0.75 MPa,the wear rate and average coefficient of friction(COF)of four-pass FSPed composite were lower than those of base composite by 53%and 50%,respectively.SEM examinations of worn surfaces,wear debris,and worn subsurfaces revealed that the intensive refinement and uniform distribution of microstructural phases,especially the coarse Si particles,reduced Si particles interspacing,and elimination of casting defects were the most important factors enhancing the substrate resistance against sliding-induced deformation.This led to the formation of stable tribolayers that improved the tribological properties.展开更多
文摘Friction stir processing (FSP) is a solid-state modification method to process the surface of metals. In this process, due to rotation and traverse motions of a non-consumable tool, metal surface microstructure is refined and its mechanical characteristics are improved. Different methods have been applied to improving the efficiency of FSP. In this research, a new method entitled friction stir vibration processing (FSVP) was presented to enhance the efficiency of FSP. In this method, metal workpiece was vibrated normal to processing line during FSP. Microstructure and mechanical properties including hardness, ultimate tensile strength (UTS) and elongation of Al5052 alloy specimens processed using FSP and FSVP methods were analyzed and compared. The results showed that grain size decreased by about 33% as vibration was applied. It was also observed that ultimate tensile strength as well as hardness increased by about 7% as FSVP was applied. This was related to the enhanced straining of metal surface material as vibration was applied. The increase in straining results in the increase of dislocation density. It leads to more development of high angle grain boundaries due to dynamic recrystallization. The results also showed that UTS and elongation of FSV processed specimens increased as vibration frequency increased.
文摘The effect of friction stir processing(FSP)at different rotation speeds(400,630,800,and 1000 r/min)and traverse speeds(25 and 50 mm/min)on the tribological properties of a Si particle reinforced Zn−40Al−2Cu-based in-situ composite was investigated.After preliminary optimization,800 r/min and 25 mm/min were selected as optimum FSP parameters.According to the results,multi-pass FSP improved the tribological properties.For instance,at an applied pressure of 0.75 MPa,the wear rate and average coefficient of friction(COF)of four-pass FSPed composite were lower than those of base composite by 53%and 50%,respectively.SEM examinations of worn surfaces,wear debris,and worn subsurfaces revealed that the intensive refinement and uniform distribution of microstructural phases,especially the coarse Si particles,reduced Si particles interspacing,and elimination of casting defects were the most important factors enhancing the substrate resistance against sliding-induced deformation.This led to the formation of stable tribolayers that improved the tribological properties.
