A Preliminary Fundamental Study On Industrialization Of Equal-Channel Angular Large Strain Technology

Severe Plastical Deformation(SPD) technology,such as Equal-Channel Angular Pressing(ECAP) etc,has become one of the most promising methods to prepare ultra-fine grained or nanocrystalline materials.The present dissertation deals with a preliminary fundamental investigation on industrialization for ECAP large strain technology.The involved contents and results are listed as follows:Firstly,the effect of ECAP processing on inclusion(AlFeMn) inside 3003Al alloy is investigated.The results show that a large refinement of AlFeMn inclusion was obtained at the first pass of ECAP,and with the increase of number of ECAP passes,the AlFeMn inclusion was distributed more and more uniform.Secondly,scale up(aluminum alloy stick with a dimension ofφ88×320mm) of ECAP large strain technology is studied using finite element dynamic simulation and actual-experimental investigation.The simulation results demonstrate that friction remains to be the major resource of ECAP pressing load.The experimental investigation suggested that the friction must be reduced for mass production of scale up materials through ECAP.Thirdly,the continuous ECA large strain technology with certain pairs of friction driving wheels is studied using finite element dynamic simulation.The results show that the driving technological parameters(angle velocity matching of driving wheels) and the radius of inner arc of ECAP die channel have an obvious influences on strain magnitude,strain uniformity,torque distribution of driving wheels,energy consuming, etc.It is found that the merely certain pairs of driving wheels can also lead to a fantastic equal-radius deforming in work-piece.Finally,the continuous ECA large strain technology with certain pairs of (different speed) rolling driving wheels was put forward for the first time.The dependence of strain magnitude,strain uniformity,torque distribution of driving wheels, energy consuming on driving technological parameters were studied.Compared with the continuous ECA large strain technology with certain pairs of friction driving wheels, this technology exhibits many advanced characteristics,such as a superior strain uniformity,a more centralizing torque,a higher strain magnitude per energy consuming (a increase of about 10 times),a larger strain magnitude per time consuming(a improvement of about 2-3 times),a more stable work-piece deformation,and an easier fabrication of thin meal sheets.There are few reports in or abroad related to the research presented in this paper. The research methods and results provide preliminary foundation for industrialization of ECAP large strain technology.