Papers by Keyword: Al-Mg Alloy

Abstract: The performance of three kinds of mold lubricants was evaluated by testing the flow length of Al-4.7%Mg alloy. The lubricants tested were a heat-insulating type with inorganic compounds (10~20%), a heat-insulating type with organic acid salts (~10%) and a water-soluble type with mineral oil (20~30%). The flow length of the alloy was longest when using the heat-insulating type with inorganic compounds, and shortest with the water-soluble type with mineral oil. Additionally, data variation was largest with the heat-insulating type with inorganic compounds, and smallest with the water-soluble type with mineral oil.

Abstract: A three-wheel caster for the fabrication of thin aluminum alloy wire was designed, assembled and tested. The first aim was to develop a caster more compact than the Properzi continuous caster. The second was to cast thin wires without burrs. The third was for the cast wire to have a cross-sectional area of less than 80 mm². The casting of Al–Mg alloy wire was tested using the developed three-wheel caster, consisting of a large lower casting wheel and two small upper forming wheels whose positions could be independently adjusted. Two types of upper wheels were tested. The casting speed was 6 m/min, and the diameter of lower and upper wheels were 600 and 200 mm, respectively. The wheels were made from copper for the rapid solidification of the molten metal. The focus of this study was on the forming of the semisolid wire by the two upper forming wheels and the ability of the device to cast wire without burrs. The influence of the position of the upper wheels on the wire properties was investigated.

Abstract: Cracks occur on the surface of Al-Mg strips cast using a high-speed twin-roll caster. Surface cracking of the as-cast strip decreases with decreasing roll load. However, the difficulty of roll casting increases as the roll load is decreased because the strip becomes brittle and is easily broken because the strip is not completely solidified. In the present study, an unequal-diameter twin-roll caster, which is capable of high-speed casting, was used with a lip attached to a back-dam plate in an attempt to decrease surface cracking without deceasing the roll load. The thickness of the solidified layer was found to decrease as the length of the solidified region decreased. The thickness of the solidified layer at the center of the width direction of a strip on the lower roll decreased by shortening the solidification length by a lip attached to a back dam-plate. The solidified layer at the edges was thicker than that inside the cast strip. The thickness of semisolid metal inside the cast strip increased more than that at the edges of the roll bite. The roll load at the width of the lip decreased. The effect of the lip length on surface cracks was investigated.

Abstract: A roll with a groove was used to decrease surface cracking on strips cast using a vertical-type high-speed twin roll caster. The roll speed was 30 m/min. Al-4.6%Mg alloy was used because surface cracking easily occurs during roll casting of this alloy. The effect of roll load on the occurrence of surface cracks in Al-4.6%Mg was investigated before the grooved roll was evaluated. Importantly, surface cracking decreased as the roll load decreased. The roll load between the edges, that is, at the groove, became smaller than that at the edges corresponding to the flanges that formed the groove. The relationship between the depth of the groove and the occurrence of cracking was investigated. The groove on the roll was useful for reducing the number of cracks. However, cracking occurred at the center of the width direction. The cause of this cracking is discussed.

Abstract: Shot-peening (SP) is one of the severe surface plastic deformation (SSPD) processing techniques. Due to large plastic strain by the SP, the SP for metallic materials forms crystallographic texture on the peened surface. Since the crystallographic texture formed by the SP depends on the dislocation slip, it can be expected that this texture is affected by stacking fault energy (SFE) of the materials. However, effects of the SFE on the crystallographic texture formed on the peened surface by the SP is not clear. In this study, crystallographic textures of pure Al (higher SFE) and Al-10 mass%Mg alloy (lower SFE) formed by the SP are investigated. When the pure Al is SPed, {001}+{111} double fiber texture with the <001> and <111> directions parallel to the plane normal direction of the peened surface is obtained. On the other hand, in the case of Al-10 mass%Mg alloy with the SFE close to the pure Cu, {110} fiber texture is formed as well as the pure Cu. Therefore, it is found that the crystallographic texture formed by the SP is influenced by the SFE.

Abstract: Fe was added to Al-4.7%Mg to make model alloys of recycled Al-Mg alloy. The effect of Fe addition on the mechanical properties of the Al-4.7%Mg strip cast using a single-roll caster equipped with a scraper was investigated. The added Fe content was 0.2, 0.4, 0.6, and 0.8%. The as-cast strip cast at 30 m/min was cold rolled down to a thickness of 1 mm thick annealed to conduct a tensile test and a cup test. The as-cast strip could be cold rolled without cracking. The tensile stress and the 0.2% proof stress were only slightly affected by the addition of Fe. The elongation gradually decreased as the Fe content increased. When the Fe content was 0.8%, the elongation in the casting direction was 27.7%. The limiting drawing ratio did not deteriorate until the Fe content was 0.4%. When the Fe content was 0.4% and 0.8%, the limiting drawing ratios were 2.0 and 1.7, respectively.

Abstract: In order to improve the plasticity of the Al–Mg alloy, which fabricated by continuous casting and rolling, the alloy was heat treated at 370 °C, 400 °C, 430 °C and 460 °C for 2 hours and cooled with the furnace. The microstructure and mechanical properties of heat-treated Al–Mg alloy under different heat treatment temperatures were analyzed. The results show that the columnar grains begin to disappear at heat treatment temperature of 460 °C. The size of equiaxed grains begins to increase as the heat treatment temperature increases. The tensile strength of the alloy decreases with the increase of heat treatment temperature and the Brinell hardness increases when the heat treatment temperature is between 370-430 °C. At heat treatment of 430 °C, the elongation and the Brinell hardness of the alloy reached to 42.91% and 70.5 HB, respectively.

Abstract: In casting of Al-Mg alloy, especially in the aluminum alloy with high Mg content of more than 4 wt.% Mg, some cold cracks were found in last freeze of the flat ingots. The depth of cracks was bigger than 200 mm. The size of scrap removal of ingot was thus increased by 70 mm or more, and the yield of the flat ingots was greatly affected. Air cooling time of more than 20 min after casting was a better to reduce cracks in last freeze of Al-Mg alloy flat ingots.

Abstract: Fe (0.2, 0.4, 0.6, and 0.8 %) was added to roll-cast Al-4.8%Mg alloy to create a model of recycled Al-4.8%Mg and its effect was investigated. An unequal-diameter twin-roll caster was used. The roll speed was 20 m/min. An as-cast strip was cold-rolled down to 1 mm and annealed. Its mechanical properties were then evaluated. The surface condition of the as-cast strip was not influenced by the Fe content. The thickness of the as-cast strip decreased with increasing Fe content. The tensile strength and 0.2% proof stress increased with Fe content up to 0.4%Fe and then decreased. When 0.8% Fe was added to Al-4.8%Mg, the tensile strength and 0.2% proof stress became higher than those for Al-Mg. Elongation and the limiting drawing ratio gradually decreased with increasing Fe content. When 0.8% Fe was added, elongation in the lateral direction was 19.6% and the limiting drawing ratio was 1.7.

Abstract: Effect of casting conditions on ripple mark and surface crack of as-cast Al-4.7%Mg strip was investigated. A vertical type high speed twin roll caster was used. A casting speed was 30 m/min. Casting conditions were tip-shape of a back-dam plate, gap between a roll and the back dam plate and texture on the roll-surface. The texture on the roll-surface was useful to reduce the ripple mark. In bending test conducted to investigate surface crack of as-cast strip, the texture on the roll surface was effective to the reduce the crack. The position of the crack was not coin side with the position of the ripple mark. This result shows that there is no correlation between the ripple mark and the ductility or the strength of as-cast strip. Small roll load was effective to reduce the crack and degree of the ripple mark. Effect of the roll load on the ripple mark was discussed including solidification delay and seepage of Magnesium.