Aluminum Alloy Strip Research Articles

Casting of Net Inserted Aluminum Alloy Composite Strip

The net-inserted metal matrix composite strip could be cast by a twin roll caster at only one process. The net could be inserted in the strip or lower surface of the aluminium alloy strip. The matrix was Al-12mass%Si, and inserted net was made from SUS304 stainless steel. The diameter of the wire of the net was 0.29mm, and distance between the wires was 0.98mm (#20). The roll speed was 30m/min. The net was not reacted with the matrix, and there was not gap between the matrix and the net. The mechanical property of the net-inserted composite strip was affected by the direction of the wire of the net. When the angle of the wire against the tensile direction was 45 degrees, elongation of the composite became better than that of the matrix from 14% up to 23%. This reason was improvement of the local contraction of the composite strip. The net-inserted composite strip could be cold rolled. The reduction of the net was smaller than that of the strip. The reduction of the wire at rolling direction was larger than that of the wire at lateral direction.

Mechanical and microstructural characterization of 6061 aluminum alloy strips severely deformed by Dissimilar Channel Angular Pressing

Dissimilar Channel Angular Pressing (DCAP) is a severe plastic deformation technique to improve the mechanical properties of flat products by producing ultrafine grains. In this study, the changes in the microstructure and mechanical properties of 6061 Al-alloy strips deformed by various numbers of DCAP passes were investigated. Some DCAPed samples were also held at 200 °C and 350 °C to investigate the effect of post-annealing. Mechanical properties were determined by hardness and tension tests; and microstructural changes were investigated by TEM analysis. Up to a critical level of plastic strain, remarkable improvements have been observed in the strength and hardness of the severely deformed strips; and the improvements have been explained by variations in grain size, dislocation structure, and formation of subgrains.

Fabrication of Aluminum Alloy Strip by Roll Caster Equipped with a Scraper

A single roll caster equipped with a scraper (SRCES) was devised in order to improve the free solidified surface. The scraper contacted to the free solidified surface at the constant force. The some amount of semisolid layer on the solid layer was removed and the surface became flat. The scraper was made from the mild steel plate. The mild steel plate was covered by the insulator paper to prevent the cooling of the melt. The melt pool was made on the roll by the side dam plates, back dam plate and the scraper. Therefore, a tip or a nozzle was not needed. In this study, AA6022 and AA5182 aluminum alloy were cast by SRCES. The scraped surface condition of the strip cast by SRCES was investigated. The free solidified surface was flat. The as-cast strip could be cold rolling. The free solidified surface could be cold-rolled and the roughness was reduced. The mechanical properties of cast strip were investigated by the 180 degrees bending test. There was no difference between the roll contact surface and the free solidified surface after cold rolling. This result showed that the free solidified surface could be improved up to the roll contact surface by the scraper and cold rolling. Furthermore, in this study, the scraper was applied to a twin roll caster. The aluminum alloy clad strip was cast by twin roll caster equipped with a scraper. Interface of the clad strip was connected and clear.

Inline Rolling of 5182 Aluminum Alloy Strip Cast by a Vertical Type High Speed Twin Roll Caster

An inline hot rolling was operated on 5182 aluminum alloy strip cast using a vertical type high speed caster (VHSTRC) at the speed of 60 m/min. A porosity existing at center line of the thickness and a ripple mark on the surface, these are typical defects of the strip cast by the VHSTRC, could be improved by the inline rolling. The rolling speed was as same as the roll-casting-speed of 60m/min. The temperature of the strip, when the inline rolling was operated, was 450oC. The reduction of the strip of the inline rolling was 35%.

Improvement of Porosity of Strip Using a Scraper on the Casting by a Vertical Type High Speed Roll Caster

Porosity occurred in the 5182 aluminum alloy strip cast by a vertical type high speed twin roll caster. The porosity was caused by high-roll-speed and low-roll-load. Improvement of the porosity was tried by a scraper. The scraper was mounted on the roll, and the scraper was moveable depend on the thickness of the solidified layer on the roll. The scraper scribed the semisolid layer to improve the porosity. The scraper was useful to decrease the porosity of roll cast 5182 aluminum alloy strip.

In-Line Rolling of Aluminum Alloy Strip Cast by a High Speed Twin Roll Caster

In-line rolling was operated on the as-cast strip cast by a vertical type high speed twin roll caster. The AA6022 and AA6111 strip was tested. The casting and rolling speed was 60m/min. Reduction was from 20% to 55%. The temperature of the rolling was within from 400oC to 450oC. The porosity and crack in the strip were improved by the in-line rolling. The in-line as rolled strip was cold rolled down to 1mm, and T4 heat treatment was operated. The microstructure of the strip, on which in-line rolling was operated, became uniform at thickness direction than the microstructure of the strip on which only the cold rolling was operated. The surface defects like the ripple mark and trace line of the nozzle were improved.

Roll Casting of Three Layers Clad Strip

A roll caster, which could cast the three layers of clad strip directly from the molten metal, was designed, assembled and tested. The base strip was AA3003 aluminum alloy and overlay strips were AA4045 aluminum alloy. An unequal diameter twin roll caster was modified to cast clad strip. Two small rolls were amounted on a large roll. A scraper plate was used to prevent the mixture of the different kinds of melts. The casting of three strips and the connecting of strips could be operated by one roll caster. The interfaces between the strips were clear, and the mixture of the melt did not occur. The clad strip could be cold rolled without the annealing. The clad strip did not peel at connecting surface by the cold rolling and continuous bending. The strips were connected strictly. The casting speed was 20m/min, and this speed was much higher than the casting speed of the conventional twin roll caster for aluminum alloys.

Radiation annealing of AMg6, 1441, and VD1 aluminum alloy strips using a ribbon source of accelerated ions

The results of our earlier studies are summed and new data are presented on the influence of beams of accelerated Ar+ ions on the mechanical properties and structure of various commercial aluminum alloys. A short-time (5–60 s) ion-beam processing of cold-deformed alloys is shown to lead to their softening, which is analogous to that upon intermediate annealing at 320–400°C for 2–3 h used in cold rolling. An experimental ribbon ion source, which is intended for in situ processing of rolled sheets in a rolling line to remove strain hardening instead of long-term furnace annealing, is described.

Roll Casting of Al-25mass%Si

Roll casting of Al-25mass%Si hyper eutectic aluminum alloy strip was tried by an unequal diameter twin roll caster. The casting speed was 10m/min. The thickness of the strip was about 2mm. The eutectic Si and primary crystallized Si were very fine by the effect of the rapid solidification. The size of the primary crystallized Si was not uniform at the thickness direction. The primary crystallized Si at the near surface was finer than that of inside. The eutectic Si was finer than 2μm. The strip could be cold rolled after hot rolling and annealing.

Formation of Internal Crack in High-Speed Twin-Roll Cast 6022 Aluminum Alloy Strip

An Al-Mg-Si based 6022 aluminum alloy, which represents a wide freezing temperature range in solidification, was cast through high-speed twin-roll casting (HSTRC). Under a roll rotation speed of 60 m/min and an initial roll separating force of 14.1 kN, the cast strip showed a large central crack, which deteriorated a quality of the cast strip. The strip exhibited an equiaxed grain structure at the near-surface region and a band of fine globular grains at the mid-central region. The large central crack was mostly observed at a boundary between the central band and dendritic solidified shell. It was considered that decrease of cooling rate near the minimum roll gap caused the cracking due to residual liquid. In order to find the condition for defect-free strip casting, HSTRC was carried out under various casting conditions. Large-scale central cracking was prevented when a sufficient roll separating force was applied by increasing a solidification time, or increasing an initial roll separating force. From a direct temperature measurement during the HSTRC using a sensitive thermocouple, it was confirmed that a cooling rate increased with increasing the roll separating force.

204 スクレイパーを用いたロールキャスターによるアルミニウム合金板の作製(溶融加工・半凝固加工,ものづくりにおける基礎研究と先端技術の融合)

204 スクレイパーを用いたロールキャスターによるアルミニウム合金板の作製(溶融加工・半凝固加工,ものづくりにおける基礎研究と先端技術の融合)

Friction and wear properties of steel backed Al–10Sn–4Si–1Cu metallic strips prepared via spray atomization–deposition-rolling route

In various load bearing structural applications related to automotive industries, steel backed aluminum alloy strips are considered. For such applications, it is desired to design appropriate alloy composition for metallic strip so that good tribological properties can be achieved. In our ongoing efforts to accomplish this aim, we have recently fabricated a steel backed Al–10Sn–4Si–1Cu bearing strip, which is prepared by spray depositing the molten bearing alloy on a steel substrate, followed by warm rolling of the resulting laminated strip to different thickness reductions up to 80%. The tribological performance of the steel backed Al–10Sn–4Si–1Cu strips is evaluated against the bearing steel. While the recorded steady state coefficient of friction (COF) does not show any noticeable difference (varying in the range of 0.6–0.7) with respect to difference in warm rolling conditions, the fretting wear rate (10–26 × 10 − 5 mm 3 N − 1 m − 1 ) of the steel backed and warm rolled strips exhibits a systematic decrease in wear rate with increase in amount of warm rolling. SEM-EDS analyses reveal the oxidative wear and the extensive cracking of alumina rich tribolayer as the dominant material removal mechanisms. The tribological properties of the spray deposited and 80% rolled steel backed Al–10Sn–4Si–1Cu bearing strip is compared with those of a commercially available Al–Sn based sleeve bearing under identical fretting conditions.

Mechanism of warm and cold roll bonding of aluminum alloy strips

From a study of interfacial behavior at deformations up to 60%, a mechanism is proposed for pressure welding of aluminum strips by rolling at warm and cold conditions, where faying surfaces were first degreased and scratch-brushed. According to this mechanism, the scratch-brushed layers fractured coherently after entering roll gap at a reduction of approximately 21%, which is regarding to the threshold deformation for roll bonding of commercial pure (CP) aluminum strips, and some small cracks perpendicular to the rolling direction formed. As deformation proceeds and roll pressure increases, these cracks quickly expanded into fissures. This process allowed the bond to be established between the underlying metals, termed virgin metals, of base metal, which were extruded through the cracks and fissures at the scratch-brushed regions. Moreover by increasing the rolling temperature, threshold deformation required for bond formation decreases.

Study on the effect of presence of TiH 2 particles on the roll bonding behavior of aluminum alloy strips

In the present study, roll bonding characteristics of commercial pure aluminum (AA1050) strips, such as bond strength and threshold deformation, in the presence of titanium hydride (TiH 2) particles and without it, were investigated. In order to evaluate weld efficiency of the roll bonding process, peeling test was carried out. The results show that in the presence of TiH 2 particles, bond strength and weld efficiency decreased for the some reduction deformation applied through roll bonding process. However, it is shown that by applying higher reduction in thickness, up to a new threshold value (about 33%, when 0.5 wt.% TiH 2 powder was used), a perfect bond with high strength can be obtained.

X-ray technique for the estimation of residual stresses after shot-blasting metal forming

A technique is developed for the correction of the depth distribution of residual stresses measured by an X-ray method with allowance for their relaxation upon the removal of surface layers. This technique is applied to the study of a D16 aluminum alloy strip subjected to shot-blasting metal forming. This technique can be used to estimate the distribution of residual stresses across massive parts after various types of treatment.

Investigation of roll bonding between aluminum alloy strips

Roll bonding is a solid-state welding process to join similar and dissimilar metals and a well-established and widely used manufacturing process. In this study, Commercial purity aluminum (AA 1100) strips were roll-bonded at warm and cold temperatures. Effects of the parameters that create successful bonds such as the amount of deformation by rolling and rolling temperature on the bond strength and the threshold deformation between two-layer strips of Al/Al were investigated. The peel strengths of the bonds were measured and found to increase when the rolling temperature or the thickness reduction are increased, and successful bonds, whose peel strength approached that of the strength of base metal, were created. In addition, the threshold deformation decreased with increasing rolling temperature.

Tribological behaviour of steel backed Al–Sn strip prepared via spray atomisation–deposition–rolling route

In recent times, considerable effort has been put into develop process routes for making steel backed aluminium alloy strips for automotive bearing applications. Al–Sn alloys are considered to be potential candidates owing to their acceptable load bearing capacity with improved fatigue and wear resistance. In the present investigation, Al–xSn (x=0, 10 and 20 wt-%) alloys were spray deposited on a steel substrate, and the resulting laminated strips were subjected to various degrees of warm rolling. The tribological performance of the steel backed Al–Sn strip was evaluated against bearing steel under fretting contacts. The fretting wear behaviour of the steel backed and warm rolled Al–10 wt-%Sn strips exhibits a decrease in wear rate with increasing amount of rolling. Scanning electron microscopy–energy dispersion spectroscopy (SEM–EDS) analyses reveal that the tribo-oxidation and adhesive wear are dominant material removal mechanisms on Al–Sn worn surfaces, while tribo-oxidation predominantly contributes to wear of pure Al.

高速双ロールキャスタにより作製した６０２２アルミニウム合金板の内部割れと鋳造条件

Influence of casting conditions on the occurrence of internal cracks for 6022 aluminum alloy fabricated by high-speed twin roll-caster was investigated. The caster used in the study was equipped with a pair of water-cooled, pure copper rolls, and a cooling slope upstream of the rolls. The strips exhibited a common microstructural feature. Columnar grains grew from both surfaces of the strip, and they were gradually replaced by equiaxed grains. In the mid-central region, a band of fine grains was observed. Such fine grains seemed to originate from the crystallized α-Al dendrites on the cooling slope or the roll surfaces. Internal cracks were observed in the 6022 aluminum alloy strip that was subjected to the highest cooling rate. The cracks were located between equiaxed grains and fine grains at the mid-central region. It was thought that the crack was caused by a lack of liquid supply at the mid-central region where the solidified shells meet together. The cracks were reduced without using cooling slope, with decreasing casting load and lowering metal head. A slight reduction in the cooling rate and reduction of α-Al generation were effective for obtaining sound 6022 aluminum alloy strips.

Semisolid Roll Casting of Aluminum Alloy Strip and Its Properties

A356 was cast into the strip by the semisolid strip casting using an unequal diameter twin roll caster. This process was one of the rheocasting. The semisolid slurry was made by a cooling slope. Solid fraction was about 5%. The casting speed was 20 m/min, and the thickness was 4.4 mm. The as-cast strip could be cold rolled down to 1 mm. The result of tension test of 1mm-thickness-T4 heat-treated strip was as below. Tensile stress was 223 MPa, 0.2 proof stress was 123 MPa and elongation was 21.8%. Deep drawing could be operated to 1 mm-thickness T4 sheet, and L.D.R was attained to 2.0. In some condition, 180 degrees bending could be operated without crack at outer surface. These results mean that semisolid roll cast A356 strip may be able to use for press forming.

727 直径1500mm双ロールキャスターによるAl合金板の作製(GS-4 材料の創成)

727 直径1500mm双ロールキャスターによるAl合金板の作製(GS-4 材料の創成)