The purpose of this investigation was to refine the grains of annealed 6063 aluminum alloy and to improve its yield stress and ul- timate strength. This was accomplished via the equal channel angular extrusion （ECAE...The purpose of this investigation was to refine the grains of annealed 6063 aluminum alloy and to improve its yield stress and ul- timate strength. This was accomplished via the equal channel angular extrusion （ECAE） process at a temperature of 200℃ using route A, with a constant ram speed of 30 mm/min through a die angle of 90° between the die channels for as many as 6 passes. The experiments were conducted on an Avery universal testing machine. The results showed that the grain diameter decreased from 45 μm to 2.8 μm after 6 extru- sion passes. The results also indicated that the major improvement in fatigue resistance occurred after the first pass. The subsequent passes improved the fatigue life but at a considerably lower rate. A maximum increase of 1100% in the case of low applied stresses and an ap- proximately 2200% increase in fatigue resistance in the case of high applied stresses were observed after 5 passes. The improvement of fa- tigue resistance is presumed to be due to （1） a reduction in the size and the number of Si crystals with increasing number of ECAE passes, （2） the aggregation of Cu during the ECAE process, （3） the formation and growth of CuA12 grains, and （4） grain refinement of the A1--6063 alloy during the ECAE process.展开更多
To improve the bending load-carrying capacity （ BLCC） of under-matched butt joint under four-point bending load in the elastic stage, the shape design of the reinforcement is studied based on the theoretics of mecha...To improve the bending load-carrying capacity （ BLCC） of under-matched butt joint under four-point bending load in the elastic stage, the shape design of the reinforcement is studied based on the theoretics of mechanics of materials. The concept, criterion, realization condition and design proposal of equal bending load-carrying capacity （EBLCC） are put forward. The theoretical analysis results have been verified by the finite element method. The simulation results are coincident basically with the ones of theoretical analysis. The research results show that the shape design of the reinforcement of EBLCC can improve BLCC of under-matched butt joint and the unilateral-side type reinforcement can replace double-side symmetry展开更多
Analysis of the recently proposed equal channel angular bending(ECAB)process is provided on thin hotrolled AZ31 magnesium alloy sheets.In particular,effects of deformation temperature and strain path on the texture ev...Analysis of the recently proposed equal channel angular bending(ECAB)process is provided on thin hotrolled AZ31 magnesium alloy sheets.In particular,effects of deformation temperature and strain path on the texture evolution and mechanical properties are systematically investigated under single pass ECAB at various temperatures and multi-pass ECAB process that involves changes in strain paths.It is found that simultaneous activation of multiple twinning types is successfully introduced during ECAB,which results in obvious tilted component of basal texture.Attributed to the domination of extension twins,weaker basal textures are detected after both single pass ECAB at 150℃and three cross passes ECAB at 200℃.After annealing,the basal texture is further weakened via twin-related recrystallization and the annealed microstructure is featured with mixture of basal and non-basal orientated grains.Additionally,the effect of grain orientation on the mode of plastic deformation and the roles of grain orientation and grain boundary on the local strain accommodation are coherently studied.This study reveals that over 60%increase of uniform elongation with marginal reduction of tensile strength less than 5%can be achieved for single pass ECAB at 150℃and three cross passes ECAB at 200℃,which is the result of larger fraction of grains favored with extension twinning and better local strain accommodation.展开更多
基金the Faculty of Engineering, University Putra Malaysia (UPM) for its supportthe Research Council and the Vice Chancellor of Research Affairs of Islamic Azad University, Takestan Branch, for their financial support
文摘The purpose of this investigation was to refine the grains of annealed 6063 aluminum alloy and to improve its yield stress and ul- timate strength. This was accomplished via the equal channel angular extrusion （ECAE） process at a temperature of 200℃ using route A, with a constant ram speed of 30 mm/min through a die angle of 90° between the die channels for as many as 6 passes. The experiments were conducted on an Avery universal testing machine. The results showed that the grain diameter decreased from 45 μm to 2.8 μm after 6 extru- sion passes. The results also indicated that the major improvement in fatigue resistance occurred after the first pass. The subsequent passes improved the fatigue life but at a considerably lower rate. A maximum increase of 1100% in the case of low applied stresses and an ap- proximately 2200% increase in fatigue resistance in the case of high applied stresses were observed after 5 passes. The improvement of fa- tigue resistance is presumed to be due to （1） a reduction in the size and the number of Si crystals with increasing number of ECAE passes, （2） the aggregation of Cu during the ECAE process, （3） the formation and growth of CuA12 grains, and （4） grain refinement of the A1--6063 alloy during the ECAE process.
文摘To improve the bending load-carrying capacity （ BLCC） of under-matched butt joint under four-point bending load in the elastic stage, the shape design of the reinforcement is studied based on the theoretics of mechanics of materials. The concept, criterion, realization condition and design proposal of equal bending load-carrying capacity （EBLCC） are put forward. The theoretical analysis results have been verified by the finite element method. The simulation results are coincident basically with the ones of theoretical analysis. The research results show that the shape design of the reinforcement of EBLCC can improve BLCC of under-matched butt joint and the unilateral-side type reinforcement can replace double-side symmetry
基金supports from KIAT(Project No.N0002598)NRF of Korea(ERC Grant No.2019R1A5A6099595)。
文摘Analysis of the recently proposed equal channel angular bending(ECAB)process is provided on thin hotrolled AZ31 magnesium alloy sheets.In particular,effects of deformation temperature and strain path on the texture evolution and mechanical properties are systematically investigated under single pass ECAB at various temperatures and multi-pass ECAB process that involves changes in strain paths.It is found that simultaneous activation of multiple twinning types is successfully introduced during ECAB,which results in obvious tilted component of basal texture.Attributed to the domination of extension twins,weaker basal textures are detected after both single pass ECAB at 150℃and three cross passes ECAB at 200℃.After annealing,the basal texture is further weakened via twin-related recrystallization and the annealed microstructure is featured with mixture of basal and non-basal orientated grains.Additionally,the effect of grain orientation on the mode of plastic deformation and the roles of grain orientation and grain boundary on the local strain accommodation are coherently studied.This study reveals that over 60%increase of uniform elongation with marginal reduction of tensile strength less than 5%can be achieved for single pass ECAB at 150℃and three cross passes ECAB at 200℃,which is the result of larger fraction of grains favored with extension twinning and better local strain accommodation.
