ULTRAFINE GRAIN FORMATION IN FCC METALS DURING SEVERE PLASTIC DEFORMATION
The evolution mechanisms of new high-angle boundaries as well as ultrafine grains in large strain were studied by means of multidirectional forging (MDF) for pure copper at low temperature and aluminum alloy at high temperature, where dynamic recovery operates as a restoration process. MDF were carried out using rectangular samples with consequent changing of the loading direction in 90o through three of mutually perpendicular axes. The structural changes can be characterized by the evolution of deformation bands such as microshear or kink bands at moderate strains. MDF accelerates the evolution of many mutually crossing microshear or kink bands developed in various directions. The (sub)grains become more equiaxed and the misorientations between them gradually increase with increase in cumulative strain, finally leading to the development of a new fine-grained structure. It is concluded that the dynamic grain formation can result from a kind of continuous reactions involving grain fragmentation due to deformation bands, i.e. in-situ or continuous dynamic recrystallization.
Ultrafine grained structure severe plastic deformation multidirectional forging grain fragmentation microshear band dynamic recovery continuous dynamic recrystallization
T.Sakai H.Miura X.Yang
Department of Mechanical Engineering and Intelligent Systems UEC Tokyo (The University of Electro-Communications) Chofu, Tokyo 182-8585, Japan
国际会议
郑州
英文
2007-10-23（万方平台首次上网日期，不代表论文的发表时间）