Equal-channel angular pressing （ECAP） is a prominent technique that imposes severe plastic deformation into materials to en- hance their mechanical properties. In this research, experimental and numerical approaches...Equal-channel angular pressing （ECAP） is a prominent technique that imposes severe plastic deformation into materials to en- hance their mechanical properties. In this research, experimental and numerical approaches were utilized to investigate the mechanical prop- erties, strain behavior, and damage prediction of ECAPed 7025 aluminum alloy in various conditions, such as die channel angle, outer comer angle, and friction coefficient. Experimental results indicate that, after the first pass, the yield strength, ultimate tensile strength, and hardness magnitude are improved by approximately 95%, 28%, and 48.5%, respectively, compared with the annealed state, mainly due to grain re- finement during the deformation. Finite element analysis shows that the influence of die channel angle is more important than that of outer comer angle or friction coefficient on both the strain behavior and the damage prediction. Also, surface cracks are the main cause of damage during the ECAP process for every die channel angle except for 90°; however, the cracks initiated from the neighborhood of the central re- gions are the possible cause of damage in the ECAPed sample with the die channel angle of 90°.展开更多
A new technique to equal channel angular pressing of tubular samples has been proposed and investigated through experiments and simulations. Deformation behavior of copper tube sample was numerically analyzed during t...A new technique to equal channel angular pressing of tubular samples has been proposed and investigated through experiments and simulations. Deformation behavior of copper tube sample was numerically analyzed during the first pass of tubular ECAP process. The investigation included the efect of various tube wall thicknesses on the efective strain magnitude and strain distribution uniformity. It is shown that tube wall thickness of 3.5 mm gives the optimum value for strain behavior. In addition, copper tube specimens with 3.5 mm wall thickness have been successfully ECAPed up to four passes with the die channel angle of 90 using flexible polyurethane rubber pad. Micro-hardness measurements on both annealed and ECAPed tubes show that 33% and 57% increases in hardness value and also, 50% and 70% reductions in the grain size were achieved after the first and fourth passes respectively. Furthermore, tube wall thickness measurements show that the process does not change the dimension of deformed specimens.展开更多
基金financially supported by the Scientific and Technological Research Council of Turkey(TüBITAK)under the 2216 Research Fellowship Program for Foreign Citizens
文摘Equal-channel angular pressing （ECAP） is a prominent technique that imposes severe plastic deformation into materials to en- hance their mechanical properties. In this research, experimental and numerical approaches were utilized to investigate the mechanical prop- erties, strain behavior, and damage prediction of ECAPed 7025 aluminum alloy in various conditions, such as die channel angle, outer comer angle, and friction coefficient. Experimental results indicate that, after the first pass, the yield strength, ultimate tensile strength, and hardness magnitude are improved by approximately 95%, 28%, and 48.5%, respectively, compared with the annealed state, mainly due to grain re- finement during the deformation. Finite element analysis shows that the influence of die channel angle is more important than that of outer comer angle or friction coefficient on both the strain behavior and the damage prediction. Also, surface cracks are the main cause of damage during the ECAP process for every die channel angle except for 90°; however, the cracks initiated from the neighborhood of the central re- gions are the possible cause of damage in the ECAPed sample with the die channel angle of 90°.
文摘A new technique to equal channel angular pressing of tubular samples has been proposed and investigated through experiments and simulations. Deformation behavior of copper tube sample was numerically analyzed during the first pass of tubular ECAP process. The investigation included the efect of various tube wall thicknesses on the efective strain magnitude and strain distribution uniformity. It is shown that tube wall thickness of 3.5 mm gives the optimum value for strain behavior. In addition, copper tube specimens with 3.5 mm wall thickness have been successfully ECAPed up to four passes with the die channel angle of 90 using flexible polyurethane rubber pad. Micro-hardness measurements on both annealed and ECAPed tubes show that 33% and 57% increases in hardness value and also, 50% and 70% reductions in the grain size were achieved after the first and fourth passes respectively. Furthermore, tube wall thickness measurements show that the process does not change the dimension of deformed specimens.
