발간논문

Home > KJMM 논문 > 발간논문

The study aims at investigating the evolution of texture structure of rectangular-shaped pure aluminum processed by cyclic equal channel angular pressing. Strong recrystallization texture consisting of cube and rotated goss components is found in an unpressed sample. {001} <011> and {110} <211> textures are obviously dominant after one ECA pressing. Typical shear texture ({111}<110> and {111}<112>) gradually increases up to two pressings but decreases for further pressing. The goss and rotated goss textures are well developed while no specific shear texture appears after four times pressing. Repetitive ECA pressings result in relatively random oriented structure compared to that of extrusion or rolling process, which is probably due to the easy rotation of fine grains to the stable orientation.

keyword : Equal channel angular pressing, Deformation texture, Shear texture, Recrystallization texture, Orientation distribution function, Pole figure

The study focuses on understanding the effect of intermediate annealing on the tensile properties and microstructure of pure Al subjected to cyclic equal channel angular pressing(ECAP). Repetitive ECAP was performed up to 16 times at maximum. As-pressed samples were annealed at 200℃ for 1 hour after 2 and 4 passages. Some annealed samples were pressed further to compare the change in the properties of pure Al with the equivalent strain induced by ECAP but different thermal history. Annealing between the repetitive ECA pressing appears to be an effective method to form an equiaxed-fine-grained structure with high misorientation angles. It decreases the aspect ratio of micrograins while keeping the grain size unchanged. Further pressing after annealing results in an increase in the aspect ratio but small decrease in the grain size. It is speculated that recrystallization of ECA pressed Al is responsible for a significant increase in the misorientation angle.

keyword : Equal channel angular pressing(ECAP), Subgrain, Annealing, Electron back scattering diffraction (EBSD), Misorientation, Recrystallization

Microstructure characterization, texture measurement and evaluation of corrosion properties were performed at various manufacturing steps from TREX to final tube for advanced Zr fuel cladding tubes. From the result of corrosion test in steam at 400℃, it was found that the corrosion behavior at the early stage was highly affected by crystallographic texture and the corrosion resistance increased when (0002) texture normal to the corrosion surface was well developed. However, the effect of texture on the corrosion behavior decreased when oxide thickness increased. It is suggested that the texture of Zr alloy plays an important role in corrosion behavior at the early stage though the corrosion behavior is dominated by oxide characteristics when thick oxide was formed.

keyword : Zr alloys, Corrosion, Microstructure, Texture, Oxide, Manufacturing process