Deformation and microstructural evolution of ultrafine- and fine-grained OFHC Cu during dynamic tensile extrusion

Dynamic Tensile Extrusion Behavior of Fine-Grained Copper Fabricated by Powder Injection Molding

“…On the contrary, it was recently reported that the DTE ductility increases as the grain size increases for ultrafine-grained (UFG, d < ~1 µm) and fine-grained (FG, ~1 µm < d < ~10 µm) Cu, which are manufactured by equal-channel angular pressing (ECAP); this is clearly an opposite trend compared with that observed for CG Cu [9]. During DTE deformation, the higher energy state and temperature increment of the UFG Cu can induce the occurrence of meta-dynamic recrystallization (mDRX) faster in comparison to the FG Cu and leads to a decrease in the DTE ductility [9]. Hence, it is revealed that the DTE ductility of the FG Cu can increase through a reduction in the residual stress and retardation of the mDRX.…”

“…Three DTE tests were conducted for each FG Cu specimen under identical DTE conditions. All fragments were softly recovered, weighed, and compared to the initial projectile weight to ensure the complete recovery [9]. DTE projectiles with a diameter of 7.62 mm were machined from FGM and FGH Cu specimens.…”

“…The DTE tests were performed with the same flyer velocities using an allvacuum gas gun, as shown in Figure 2. Details of the DTE facility and procedure, including the configuration of the DTE projectile and die, are described in the literature [5,9]. A high-speed camera was set up to measure the projectile velocity and verify the number and order of fragments exiting the DTE die.…”

“…It has been reported that the DTE ductility of oxygen-free high-conductivity Cu under the same projectile velocity increases with a decrease in the grain size in the coarse grain (CG) range over 10 µm as a result of grain refinement and dual <001> + <111> texture development [4][5][6]. On the contrary, it was recently reported that the DTE ductility increases as the grain size increases for ultrafine-grained (UFG, d < ~1 µm) and fine-grained (FG, ~1 µm < d < ~10 µm) Cu, which are manufactured by equal-channel angular pressing (ECAP); this is clearly an opposite trend compared with that observed for CG Cu [9]. During DTE deformation, the higher energy state and temperature increment of the UFG Cu can induce the occurrence of meta-dynamic recrystallization (mDRX) faster in comparison to the FG Cu and leads to a decrease in the DTE ductility [9].…”

“…where l i is the longitudinal length of the i th fragment and l 0 is the initial diameter of the projectile. The condition of the DTE test is similar to the jet formation of the shaped charge mentioned above; therefore, the DTE ductility was applied to evaluate the jet formability of several liner metals and alloys [4][5][6][7][8][9]. It has been reported that the DTE ductility of oxygen-free high-conductivity Cu under the same projectile velocity increases with a decrease in the grain size in the coarse grain (CG) range over 10 µm as a result of grain refinement and dual <001> + <111> texture development [4][5][6].…”