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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.

For CO2 emission reduction, an incremental flattening process in which sheet metal waste is recycled with non-heating has been proposed. In this process, a bent sheet is unbent into a sheet metal with a triangular residual corner, and this residual corner is flattened incrementally. During the incremental flattening, the thinned bent corner can be thickened. However, this incremental flattening process has a problem in which the thickness of the bent corner after flattening is thinner than the thickness of the surroundings. To overcome this problem, we investigated the thickening behavior of the bent corner during the incremental flattening and experimentally clarified the possibility of the increase in the thickening of the bent corner from considering of this thickening behavior. It was found that the bent corner buckled during incremental flattening. Experimental results showed that this buckling of the bent corner was controlled by shortening the length of the triangular side of the residual corner, and the thickening of the bent corner increased. Furthermore, work-hardening exponent of sheet metal influenced on the thickening of the bent corner.

The effect of surface roughness on glossiness and surface color for anodized 5052 aluminum alloy plates were investigated. The surface roughness of aluminum alloy plate was controlled by processing of shot blasting to satisfy the condition of arithmetical mean roughness, Ra, less than 1.0 μm. The specimens with several different conditions were prepared: shot blasting, anodizing after blasting, and, in addition, it dyed it to red, green and blue respectively. CIELAB (L*a*b* color system) was applied to the surface color evaluation method. The results of experiments, the glossiness value, Gs (60°), increased as decreasing Ra. The lightness, L*, decreased as decreasing Ra. The hue angle, hab, of the anodized surface changed into the green direction. The a, b chroma, C*ab, decreased as decreasing Ra of the anodizing red and blue specimens. However, the a, b chroma, C*ab, increased as decreasing Ra of the anodizing green specimen. This was caused by the fact that the hue angle, hab, changes into the green direction by anodizing.

In this study, we performed semisolid casting of the 5052 aluminum alloy using an inclined cooling plate to find the casting conditions for the finest grain size in the solidified structure. The casting conditions in this experiment were pouring temperatures onto the inclined cooling plate, length and angles of the cooling plate, and thickness of BN coating on the cooling plate. Although the solid-liquid coexistence zone of the 5052 alloy is narrower than that of the AC4CH alloy, the inclined cooling plate is useful, and we obtained an average grain size of 60 μm. The BN coating film must be as thin as possible because of the significant undercooling of the molten alloy. Greater undercooling causes more increased nucleation and more increased number of crystals to grow on the cooling plate. As a result, fine and granular crystals were obtained. The thermal boundary layer between the BN coating layer and the molten alloy, and the undercooling of the molten alloy were influenced by the flow speed of the molten alloy on the plate.

The corrosion behavior of deposited magnesium film on AZ31 alloy, pure magnesium and AZ31 alloy were studied from the measurement of electrochemical impedance spectroscopy (EIS) in 0.5 mol/dm3 sodium chloride solution (pH 6.5) at 308K. The magnesium film on AZ31 alloy was prepared by evaporation process using 3N-Mg (99.9mass%Mg) material and the thickness of the film was 100 μm. The corrosion potentials of magnesium materials became negative value with decreasing these impurities contents. Corrosion resistance of magnesium materials measured by EIS increased with decreasing these impurities. It is found that the corrosion resistance and corrosion potential of deposited magnesium film correspond to that of 6N-Mg (99.9999mass%Mg).

The changes of pore in DC slab, after homogenized and after rolling were systematically investigated. It was found that pore size and number in the slab after the homogenization generally increased, and over 150 μm in size of the pore near the center of slab were observed. The pore size in the center of thick plate rapidly increase after rolling, and they grow as a double in comparison with the pore size after the homogenization. In this study, to understand the change of pore size during manufacture processing of thick plate, FEM modeling of the rolling process was performed for explaining why the pore become coarse during hot rolling process. From the contrast of FEM results and measurement results of the pore, the pore coarsening phenomenon of 5052 aluminum alloy thick plate in the rolling procedure was clarified. Main conclusions are shown below. (1) The FEM results show that the pressure by the roll affects only the thick plate surface and show that there is a negative pressure (tension) taking place in the center of plate when the rolling reduction is small. Therefore, it is supposed the pore size near the center increase by the tension force. (2) It is considered that stress ratio of the thick plate (rolling direction component/directional component) can be used as one of the criteria of the porosity coarsening during rolling process.

This paper is investigated experimentally about the effect of topography to the glossiness and surface color in order to characterize a surface texture of aluminum alloy 5052. The surfaces of specimens are machined by using a vertical milling machine, a horizontal milling machine and a shaping machine. Four kinds of specimens are machined by each machine so that the arithmetical mean roughness value, Ra, is less than 1 μm at four cutting conditions. From the results of experiments, the glossiness values of the vertical milling surface and the horizontal milling surface were about the same value, meanwhile the glossiness value of the shaping surface was less than half the value of the others. The surface color of specimens was gray. Especially, The lightness value of surface color, L*, of the horizontal milling surface was the highest value. The surface color was whitish gray of all machined surface. Based on those experimental results, it was summarized that the surface texture of specimen machined various machine could be characterized by the glossiness and surface color. These results could be an effective indicator in choosing the most proper machining method to add value to surface texture.

5052 aluminum alloy to pure titanium were friction welded using a continuous drive friction welding machine. Effect of using an insert metal on the microstructures and mechanical properties of the dissimilar friction welded joint was investigated. Friction welded joints without insert metal were observed compound layer and the thickness of intermetallic compound layer were irregular and thick. Friction welded joint with insert metal, its compound layer became thin and generated comparatively evenly. In spite of the existence in the friction welding of the use of the insert metal, the hardness of compound layer of both welded joints showed higher than those of the both base metals. Tensile strength of welded joint without insert metal showed 78% of 5052 aluminum alloy and it's fractured at weld interface. But, in case of welded joint using an insert metal, the tensile strength showed 92% of 5052 aluminum alloy. The elongation of welded joints with insert metal was improved. All the welded joints with insert metal were fractured at softened area of heat affected zone of 5052 aluminum alloy side in tensile test.

5052 aluminum alloy used for substrate and consumable rod, was friction surfaced using a numerical controlled full automatic friction welding machine. Effects of the surfacing conditions on some characteristics of deposits were investigated. It was clearly observed that the circularly pattern appeared on the surface of deposit by the rotation of consumable rod. The deposit has a tendency to incline toward the right side further than center of deposit for the feed direction of consumable rod. This deviation accompanied the decrease of the rotational speed of consumable rod. The width of deposit increased with increasing friction pressure, and decreasing rotational speed of consumable rod. The thickness of deposit became thinner when the consumable rod was high revolution. The surfacing efficiency decreased with increasing friction pressure and rotational speed of consumable rod, but increased with increasing feed speed. Microstructure of the deposit was finer than that of the substrate and consumable rod. The softened area was recognized at 3 mm distance from the weld interface of substrate. The tensile strength of deposit increased with increasing friction pressure. The maximum tensile strength of deposits showed 88.8% of the base metal of substrate.

5052 aluminum alloy matrix/titanium composites with about 8, 18 and 47 volume percents of titanium were fabricated by a simple method; compressing alternately multilayered 5052 aluminum alloy foils and pure titanium foils at room temperature. The initial thickness of titanium foils was 10, 25 or 102 μm and that of 5052 aluminum alloy foils was 115 μm. The composites obtained show the multilayered structure of the aluminum alloy and pure titanium phase extended in two dimensions. Many cracks are generated in titanium foils with the initial thickness of 10 μm during compressing and the number of cracks formed decreases with increasing thickness of titanium foils. No crack is detected in titanium foils with thickness of 102μm. Interlaminar shear strength between the aluminum alloy and titanium phases increases with the volume fraction of titanium phase and with the total reduction. The measured values of tensile strength of the composites are nearly in agreement with the values estimated from the rule of mixture on continuous-reinforced composites.

The mechanically mixed layer at a weld interface and the mechanical properties of dissimilar welded joints of 5052 aluminum alloy to 2017 aluminum alloy, which were made by using a brake type friction welding machine were examined with different welding conditions. The mechanically mixed layer is formed on the friction process, and it is observed at a weld interface all over. The thickness of the mechanically mixed layer decreased with increasing friction pressure, the mixed layer of the outside of joint became thinner than that at the center. The tensile strength of joints which were made with the friction pressure of above 45 MPa, which had an average thickness of 200 μm in mechanically mixed layer, showed 85% of 5052 aluminum alloy base metal. The breakage occurred at the softened area of 5052 aluminum alloy side. The impact strength of joints, which had an average thickness of 200 μm in mechanically mixed layer, were 70% of 5052 aluminum alloy base metal.

A reduced-current resistance spot welding technique, which utilizes the heat of reaction from reactive inserts together with the Joule heat, has been applied to join aluminum alloy A5052–H34 sheets to pure copper C1100–O sheets. Employing elemental powder mixtures of Ti–Al and Ti–Mn binary systems as the reactive inserts, well balanced tensile shear load and bonded area are obtained by the latter insert especially in a composition of Ti–75Mn. Since expulsion causes damage to the joint strength strongly, welding conditions are investigated to prevent the strength decrease. Application of a F-type electrode in the aluminum side is effective to avoid the surface expulsion by chilling the melted zone formed through the thickness of the aluminum alloy sheets during welding. As the mating electrode in the copper side, a CF-type one with a tip diameter just larger than that of the melted zone is effective to prevent the inter-layer expulsion by its forging effect. When a welding current of 12 kA is applied for 0.2 s with Ti–75Mn insert and welding force of 1 kN to join aluminum alloy sheets of 1 mm and 2 mm in thickness to copper sheet of 1 mm in thickness, tensile shear loads over 1.5 kN and 1.9 kN are achieved by the use of an electrode pair of CFφ6(Cu)/F(Al), respectively.

The quantitative evaluation of the surface fatigue crack size initiated from an artificial surface defect has been attempted using a DC potential drop (DCPD) technique for an aluminum alloy. A 5052–H34 aluminum alloy sheet with a small blind hole as a surface artificial defect has been used. Potential drop defined as a function of crack area and the correction factor α obtained from experimental data have been used in order to estimate crack depths. The estimated crack depth was slightly smaller than the actual crack depth. The measurement accuracy will be improved by increasing the sensitivity of potential measurement. The surface crack initiated from the artificial surface defect propagated with an almost constant aspect ratio a/c (a: crack depth, c : half crack length) after the crack reached the bottom of the artificial defect under the condition employed in this study.

Effect of inclination of faying surface on the mechanical properties of 5052 aluminum alloy joints, which were welded by a brake type friction welding machine, has been investigated. The inclination angle of faying surface to the specimen axis was 0° to 25°. The axial shortening increases at first rapidly and then slowly with increase in the welding time. It is found that the initial axial shortening speed increases with increasing the inclination angle. Regardless of the friction time, both burn off length and total loss increased with increasing inclination angle. Heat affected zone of welded joints became narrower with increasing inclination of faying surface. The inclination of faying surface had no effects on the microstructures of joint. Hardness of weld zone was lower than that of the base metal. The width of softening zone tended to decrease with increase in the inclination angle. Tensile strength of the welded joints was 84% as large as that of the base metal independent of the inclinatin angle of faying surface. Regardless of both welding condition and inclination of faying surface, the elongation of welded joints was 81% as large as that of the base metal. All joints fractured at the heat affected zone.

The surface fatigue crack propagation behavior has been investigated under tension-tension cyclic stress at two different frequencies in 3 mass% NaCl aqueous solution for the 5052 and 5083 aluminum alloys, and 1100 commercially pure aluminum sheets with an artificial surface defect. While the fatigue life (number of cycles to failure) at low frequency is obviously longer than that at high frequency in 5083 alloy and 1100 aluminum, the fatigue life is almost independent of the frequency in 5052 alloy. The reduction of fatigue life is largest for 1100 aluminum containing almost no addition of Mg which generally improves corrosion resistance of an aluminum alloy. The fatigue life for 5083 alloy, which is assumed to have β phase more than 5052 alloy because of differences in Mg content and heat treatment, is lager than that for 5052 alloy. In the early stage of fatigue crack when propagation is governed by corrosion environment, surface crack propagation rate at low frequency tends to be slightly higher compared with that at high frequency for 5052 alloy. Further, the 5052 alloy exhibits the flatter front shape of fatigue crack at failure at the lower, because the surface crack propagation is more accelerated by corrosion effect.

Theoretical γ-values calculated from crystallite orientation distribution functions by using the Taylor theory have been compared with experimentally measured γ-values in annealed aluminum alloy sheets. The calculated and measured γ-values for a 6061 aluminum alloy consisting of the retained rolling texture and of the cube texture are relatively well consistent, but these values for a 5052 aluminum alloy consisting mainly of the cube texture are less consistent in the vicinity of a 45° direction. This is thought to be essentially due to the lack of validity of an analytical model for the 5052 alloy. Planar anisotropy of the γ-value, however, can be generally estimated by the present model. From the calculated results concerning some ideal orientations, it is found that a high γ-value may be obtained by developing the R-orientation as a main component and the Goss orientation as a secondary component.