A Fundamental Study On Equal Channel Angular Large Strain Technology Towards Application

ECA-P （Equal Channel Angular-Pressing） is one of the most important large strain technologies for refining and regulating microstructure of metallic materials. However, it is difficult for industry application due to the realization of scale-up and continuation. Around the problems, the work has obtained results of the present dissertation are listed as follows:（1） Scale-up and quantity production of ECAP were conducted by FEM and experiment. The results indicate that the mold corner is a key parameter for the ECAP technology realizing quantification production, and reducing the max pressing load effectively. The results show a reasonable valueΦ100°to 120°both can realize the quantity of pushing continuous production, and be able to reduce the load, at the same time maintain the large processing strain.（2） The ECAP technology with movable bottom were investigated using Deform-3D software, with special focus on the relationship among maximum pressing load, strain, the ratio of movable bottom sliding velocity to pressing velocity （v₂/v₁）, as well as the friction coefficient between work-piece and the movable bottom in exit channel.The results show that with the increasing of v₂/v₁, the maximum pressing loads are varying always in the manner of decreasing, and the effective strain changes according to Boltzman function. Moreover, the strain deviations decrease considerably, and with a 240% improvement in strain distribution uniformity. It is found that the effects of the friction coefficient between work-piece and the movable bottom on maximum pressing load and strain are related to the ratio of v₂/v₁.（3） The LSR-ECA （Large Strain Rolling-Equal Channel Angular） technology large strain was investigated using FEM. It is found that, the LSR-ECA technology can produce the work-piece without length limit, the rate of speeding of rolling wheels have an important effect on the distribution of strain, while the magnitude of speeding has little effect on temperature.（4） The LSR-ECA experimental investigation of the 5052 aluminium alloy was carried out. The results indicated that the LSR-ECA technology can produce the work-piece without length limit. The TEM （Transmission Electron Microscopy） examination explore an equiaxed grain （sub-grained） with the orientation difference of approximately 2°.The hardness measured indication the hardness improve enormous by 90%.