This study examines the deformation behavior and microstructural evolution of 6061 aluminum alloy processed through severe plastic deformation (SPD) via biaxial alternate forging. The objective was to evaluate both the alloy's formability limit and mechanical properties. Finite element (FE) analysis was conducted to simulate the biaxial alternate forging process, incorporating the strain-hardening coefficient and the number of forging passes. When the strain-hardening coefficient was set to 0, an average effective strain of approximately 440% was observed in a 4 mm diameter region at the core of the workpiece after eight forging passes. In contrast, with a strain-hardening coefficient of 0.2, the average effective strain under the same conditions decreased to about 300%. The FE analysis of the 6061 aluminum alloy estimated an average effective strain of 326% after eight passes, indicating a level of severe plastic deformation well beyond the elongation capacity of the initial material. Tensile testing revealed that after two passes, the material showed a gradual increase in strength with only a minimal reduction in elongation. Even after accumulating a significant strain of 326% through eight passes, optical microscopy displayed deformed grains and twinning structures, with no signs of recrystallization across all examined forging conditions.

Additive manufacturing (AM) technology, also known as 3D printing, is a highly promising technology that can drive innovation in various industrial areas, including the nuclear industry. Although the nuclear industry is traditionally conservative when it comes to adopting new technologies, it is crucial that AM technology is eventually applied for a variety of reasons. To overcome the barriers that currently hinder the adoption of AM in the nuclear industry, it is essential to ensure the reliability of AM products. One key factor is ensuring that AM products have mechanical properties equivalent to those of traditionally manufactured products. This paper presents the results of mechanical property tests conducted on additive manufactured specimens of stainless steel 316 L after heat treatment. We performed tensile tests, hardness tests, and microstructure analysis on specimens produced using two types of metal AM technologies: powder bed fusion (PBF) and directed energy deposition (DED). The results of the tests indicate that certain weaknesses, such as anisotropy and brittleness, in AM products can be improved through three types of heat treatments. In particular, AM products produced using the PBF method and subjected to heat treatments show potential for application in the nuclear industry in terms of materials.

The elastic property of a copper (Cu) thin film was investigated using the surface acoustic wave (SAW) measurement technique. The Cu film was deposited on a quartz substrate using a direct current magnetron sputter and its surface morphology was inspected using atomic force microscopy. Time-domain waveforms of the SAW on the film were acquired at different propagation distances to estimate the Young’s modulus of Cu such that the experimentally-obtained dispersion curve can be compared to the analytical result calculated using the Transfer Matrix method for curve-fitting. Results showed that the film’s elastic property value decreased by 18.5% compared to that of the bulk state, and the scale effect was not significant in the thickness range of 150-300 nm, showing good agreement with those by the nanoindentation technique. The property, however, increased by 15.5% with the grain coarsening.