Takuya Suzu

Bio: Takuya Suzu is an academic researcher from University of Hyogo. The author has contributed to research in topics: Deformation (engineering) & Magnesium alloy. The author has an hindex of 1, co-authored 2 publications receiving 13 citations.

EBSD Observation for Reversible Behavior of Deformation Twins in AZ31B Magnesium Alloy

Abstract: A bending device used for SEM-EBSD systems has been developed by the authors, which enables one to intermittently observe changes in microstructures induced by deformation in the same viewing area. Alternate compression-tension loading was applied to a sheet specimen of AZ31B magnesium alloy by bending the specimen. Twins were formed by compression straining. They remained after un-loading. Applying tensile straining lead to the disappearance of all the twins. Most of twins were those of {10\\bar12} types. Anisotropy in mechanical properties of magnesium alloys would be affected by this twinning and de-twinning behaviors.

Texture control on AZ31B magnesium alloy by wavy form rolling with roll heater

Abstract: Grain refinement, randomization of texture and improvement of mechanical properties on AZ31B magnesium alloy were attempted by applying the wavy form rolling method. Specimens were heated at 523 K and then wavy form rolling, followed by reheating at the same temperature and rolled again. The wavy rolls were heated at 423 K by attached roll heaters. Cracking did not occur during wavy form rolling. This process was repeated 8 times, then the specimen was flattened using conventional flat rolls at room temperature and finally annealed at various conditions. Grain sizes in the specimens were determined by optical microscope. Textures formed in the specimens were analyzed by electron backscattered diffraction measurements. Mechanical properties in the specimens were evaluated by tensile tests. The wavy form rolling and decreasing rolling temperature were useful for randomization of texture. But annealing after wavy form rolling at higher temperature and for longer time caused the basal plane texture. Anisotropy in mechanical properties of the wavy form rolling specimens was decreased in comparison with those in the starting materials.

Work-hardening behaviors of magnesium alloy sheet during in-plane cyclic loading

Abstract: This paper presents the work-hardening behaviors of a rolled AZ31B magnesium alloy sheet during in-plane cyclic loading. The overall trend of the stress–strain curve was as follows. As established before, the yield stress under compression was considerably less than that under tension, and an inflected shape was observed in the stress–strain curve during the subsequent tension. Furthermore, an asymmetric evolution of work-hardening was observed as follows. The rate of work-hardening in the late stage of compression became gradually large with an increase in the number of cycles. Owing to this increase in the rate of work-hardening, the stress at the end of compression increased as the number of cycles increased. On the other hand, the rate of work-hardening in the late stage of tension became small as the number of cycles increased, yielding a decrease in the stress at the end of tension with the increase in the number of cycles. The results were almost the same when the cyclic loading test was carried out after tensile strain was applied to the sheet. On the other hand, when the cyclic loading test was carried out after compressive strain was applied, the increase in the rate of work-hardening in the late stage of compression was significantly more pronounced, whereas the inflected shape of the curve during tension was considerably less pronounced. The mechanisms of the above macroscopic behaviors were investigated in terms of twinning.

3 – Twinning and its role in wrought magnesium alloys

Abstract: : In magnesium and its alloys, twinning plays a critical role in determining many characteristics of the mechanical response. The present chapter provides an overview of twinning in magnesium base alloys with a focus on recent advances made using new techniques such as electron backscattering diffraction, advanced phenomenological models and atomistic modelling. The present chapter is organized to first present the reader with a picture of the fundamental features of twinning. Next, the manner in which twinning affects the mechanical response is examined. Finally, the scope to manipulate twinning with the metallurgical ‘tools’ of alloying and processing is considered.