体育保健
打工不如创业
Trans.Nonferrous Met.Soc.China26(2016)3081−3090
Significant improvements in mechanical properties of AA5083aluminum alloy using dual equal channel lateral extrusion
N.FAKHAR1,F.FERESHTEH-SANIEE1,R.MAHMUDI2
1.Department of Mechanical Engineering,Faculty of Engineering,Bu-Ali Sina University,Hamedan65178,Iran;
2.School of Metallurgical and Materials Engineering,College of Engineering,University of Tehran,Tehran,Iran
Received22November2015;accepted27September2016
Abstract:Dual equal channel lateral extrusion(DECLE),as a vere plastic deformation(SPD)process,was employed for improving the mechanical properties of AA5083aluminum alloy.Several experiments were conducted to study the influences of the route type,namely A and B,and pass number on mechanical properties of the material.The process was conducted up to6pass with decreasing process temperature,specifically from573to473K.Supplementary experiments involving metallography,hardness and tensile tests were carried out in order to evaluate the effects of the process variables.The hardness measurements exhibited reasonably uniform distributions within the product with a maximum increa of64%via a6-pass operation.The yield and ultimate strengths also amended107%and46%,respectively.The significant improvements were attributed to the vere shear deformation of grains and decreasing pass temperature,which intensified the grain refinement.TEM images showed an average grain size reduction from100µm for the annealed billet to200nm after6pass of DECLE.Finally,the experimental findings for routes A and B were compared
and discusd and some important conclusions were drawn.
家庭账本>地瓜面
Key words:AA5083aluminum alloy;vere plastic deformation;dual equal channel lateral extrusion;hardness homogeneity
四条红线>南澳西冲>清纯美女图片1Introduction
三角形三边关系
Production of ultra-fine and nano-structured materials by means of vere plastic deformation(SPD) techniques has attracted many rearchers during the last decade.The methods are capable of providing superior mechanical properties,namely;high yield and ultimate strengths,extended fatigue life,and,in some cas, greater ductility at lower temperatures[1].SPD techniques could also be implemented for a wide range of materials including structural and functional materials. Besides structural materials,ultrafine,nanocrystal and amorphous microstructures could be created in shape memory alloys as functional materials[2−5].Several SPD methods have been propod,which can be divided into four categories bad on the geometry of the specimen.Some of the SPD techniques such as equal channel angular pressing(ECAP)[6],cyclic extrusion compression(CEC)[7],cyclic expansion extrusion(CEE) [8],twist extrusion(TE)[9],and simple shear extrusion (SSE)[10]are employed for inducing high strains into the rods.On the other hand,veral operations including high
pressure torsion(HPT)[11],accumulative roll bonding(ARB)[12],repetitive corrugation and straightening(RCS)[13],high ratio different speed rolling(HRDSR)[14]and equal channel angular rolling (ECAR)[15]have been introduced for production of fine grain sheets.The mechanical properties of tubes can also be improved by means of process such as tube channel angular pressing(TCAP)[16],high pressure tube twisting(HPTT)[17],tube channel pressing(TCAP)[18] and tube high pressure shearing(T-HPS)[19].Finally, two operations,namely ECAP of plates[20]and repetitive uptting(RU)[21]were propod for production of plates with fine-grain structures.The latter process was firstly introduced with another appellation, namely dual equal channel lateral extrusion (DECLE)[22].Among the above mentioned SPD process,ECAP operation is the most applicable and effective technique for refining the structures of different materials.The inherent attractiveness and advantages of this process have resulted in development of some new SPD methods,such as TCAP,ECAR and T-shaped equi-channel angular pressing(T-ECAP)[23].
The DECLE process is one of the operations
Corresponding author:F.FERESHTEH-SANIEE;Tel:+98-81-38292630;Fax:+98-81-38292631;E-mail:ffsaniee@basu.ac.ir DOI:10.1016/S1003-6326(16)64440-0
