Macroscopic segregation occurs easily at the center of materials with large cross-sectional areas, such as blooms, billets, and ingots. Segregation affects the workability and certain other properties such as mechanical strength and corrosion resistance through phase transformation. Therefore, it is important to manufacture homogeneous materials by eliminating segregation. In this study, the influence of manufacturing conditions on the diffusion of segregation is examined. It was found that the diffusive behavior of some elements in the segregation part depended on the rolling ratio, which is defined as the ratio of the areas of the cast material and the rolled material. And it was possible to estimate diffusive behavior using a parameter including Ld/Hm, where Ld is the contact length and Hm is the mean thickness before and after rolling. In addition, from a comparison of conventional and heavy reduction rolling conditions, we suggested that the recrystallization affected the segregation diffusion behavior.

To improve the formability of rolled AZ31B magnesium alloy sheets at room temperature, the in-plane direction was restricted by precompression along 0 (rolling direction: RD), 30, 45, 60, and 90° (transverse direction: TD) from the rolling direction of the alloy sheets whose strain levels relative to the transverse direction were either 0.055 or 0.11. To avoid buckling during bending, a special fixture with comb teeth for thin sheet compression has been developed. The strong orientation of the basal rolling texture of the sheet was weakened after in-plane compression, and coarser grains were observed. The stretch formability was also improved. The circumferential strain (ε_θ ) value was dramatically increased from 0.14 (as-received) to 0.30 (precompressed 11.0%) in Mg specimens. Recrystallization and grain growth occurred in grains with higher deformation energy compared with those having less energy after annealing at 250 °C. The intensity of in-plane anisotropy generated at the flange edge of the drawn product could be controlled to some extent by introducing precompressive strain.

We studied a method of evaluating the strain distribution of a steel sheet after tensile forming using high-frequency ultrasonic wave. The longitudinal wave sound velocity after tensile forming, for eight different steel sheets with tensile strengths of 270 MPa to 980 MPa, increased in all samples. Furthermore it was also possible to evaluate strain distributions in press-molded parts formed by draw forming, one-step form forming, and two-step form forming. We found that the measurement results of ultrasonic waves correspond to the residual stress and FWHM in XRD measurements.

A large roll-over is formed on the cut edge around the convex portion of the blanked component and it causes some functional problems in gear products. This study is aimed at revealing the mechanism of roll-over formation and identifying the parameters affecting the formation. Through experiments using annealed pure aluminum, the increase in the height of roll-over d_p as in figures was observed to be independent of the punch-die clearance for a small convex-tip radius, whereas the roll-over height d_p increased only with large clearances for a large tip radius. Numerical results agreed well with the experimental results and suggested contributions of indentation deformation and radial material flow occurring at the convex tip to the increase in roll-over height d_p .