Intermittent observations have been carried out on an early stage of recrystallization in Al–Mg–Si–Cr alloy with using an SEM-EBSD system. The specimen of Al–0.7%Mg–0.4%Si–0.2%Cr alloy was solution heat treated at 813 K for 3.6 ks, and then mechanically polished and finished by electropolishing. Vickers indentations were applied on the surface for landmarks. The specimen was cold-rolled at R. T. with about 30% of a reduction rate. After an EBSD observation, the specimen was cut into about 5×5×2 mm in size. Annealing the specimen at 673 K with using a molten salt bath, ion-polishing of the surface of the specimen for 180 s, and observing with the SEM-EBSD system were repeated. Intermittent observations on the same area were carried out during annealing up to 60 s. All the grains were rotated by cold-rolling. Deformation was inhomogeneity even in the same grain. Recovery was observed as formation of subgrains after annealing for 3 s. Subgrains having a similar orientation to the mother grain showed subgrain growth with annealing out of heavily deformed region. Such a subgrain growth was followed by formation of small grain without subgrains and surrounded by large angle grain boundary. Stress induced boundary migration was also observed.

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In the shearing aluminum sheets, such as blanking and punching, aluminum whiskers and a large amount of powders are generated on the cutting surfaces, in and around the die respectively. This unwanted loss of material may cause deterioration of the dimensional accuracy of products and a decrease in working efficiency, which are considered as problems in production sites. In this study, we observed the condition of the cutting surfaces upon shearing deformation and clarified three causes of material losses. Next, we proposed the method of precision punching, which enables us significantly to suppress the generation of whiskers and powder simultaneously. Precision punching is an improved method of reciprocating blanking and is a type of burr-free blanking. Specifically, a workpiece is given to a small penetration that will not be developed into a crack, using a half blanking punch with an edge angle larger than 90°. The workpiece is then punched from the opposite direction using a punch with an edge angle of 90°. The experiment clearly seen that this method using a rectangular punching die can perform cutting surface without whiskers, which the amount of powder generated in and around the die can also be significantly reduced.

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The purpose of this study is to estimate the elastic modulus, strength and ductility of porous Ti6Al4 V alloy prepared by spark plasma sintering process using gas atomized powders. Porous alloys have nominally 0, 20, 30 and 40% porosities after sintering. Three-point bending test has been carried out to evaluate the effects of porosity on strength to biomaterials application. In order to investigate an effect of microstructures on materials properties, tensile properties and elastic modulus have also been measured with 20% porosity Ti6Al4 V/PMMA composites and 20% porosity Ti6Al4 V alloy treated by solid solutioning, annealing and ageing respectively. Bending strength lineally decreases with increasing porosity at a range from 20 to 40%. It has been showed that all heat treated or composites specimens have a superior strength property compared with human cortical bone. Elastic modulus has been estimated around 40~48 GPa, and failure strain has a range from 0.8 to 1.0% in all specimens. Both tensile strength and strain depend on porosity rather than the microstructure of particles after heat treatment. 20% porosity Ti6Al4 V/PMMA composites give a smooth surface to porous samples without a degradation of strength characteristics. Ductile fractures are observed on particle surfaces after tensile test, and it is indicated that a bonding between particles after sintering is strong.

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The rolling textures evolution of AZ31 magnesium alloy sheets is investigated by the eccentric-rolls drawing as a simulated rolling. The eccentric-rolls provides a sheet continuously changing in rolling reduction, and a exact processing temperature is ensured by uniformly heating the free-rotatable rolls together with a test piece in a furnace. The formed textures at the different rolling rates of 10 and 100 mm·⁻¹ showed no significant differences in any temperature and rolling reduction. The double peak texture, which appreciably improves low-temperature formability of this alloy, was obtained under rolling reduction of 22% or above at 423–523 K. On the other hand, at 573 K, the texture was typically concentric circle.

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In-situ observation of magnetic pulse welding process using a one-turn coil was performed by using a high-speed video camera. High-speed deformation and collision behavior of the metal plates were investigated. The flyer plate traveled toward the parent plate with a high speed by the generated electromagnetic force. A collision velocity of the flyer plate to the parent plate was 250 m/s at the representative welding condition (initial gap distance between two plates: 1.0 mm, discharge energy: 2.5 kJ). It was clearly observed that a part of the flyer plate which was located along the coil bulged toward the parent plate. The collision angle between metal plate surfaces was 0° at the initial collision point, but it increased continuously during the welding. Such a characteristic high-speed oblique collision is considered to result in formation of the wavy interface and gradual changes in its wavelength and amplitude along the welding interface.

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