Papers by Keyword: Strip Casting

Abstract: High-speed roll casting of AC2A aluminum alloys for casting was performed at speeds from 20 to 40 m/min using an unequal-diameter twin-roll caster to investigate the improvement of ductility and sheet forming with roll-cast strips. The width of the cast strips was 100 mm. The roll-cast strips were homogenized and cold rolled to a thickness of 1 mm, and the resulting cold-rolled strips were then annealed before tensile testing, deep drawing, V-bending, and three-roll bending. Tensile testing was also performed for a T6 heat-treated test piece. The microstructure was observed using optical microscopy.

Abstract: The molten steel level in twin-roll strip casting (TRC) has a significant impact on the heat transfer process between the molten steel and the rolls, as well as the subsequent solidification process of the steel. Therefore, ensuring a specific and stable molten steel level is crucial for the quality of as-casting strips. To achieve this, a precise and real-time molten steel level detection system is required. This paper utilizes machine vision technology to measure the molten steel level. A general mathematical model for the molten steel level in the TRC process is established. An image processing method for measuring the molten steel level using a single camera is proposed, including image segmentation, edge detection, and multiple coordinate transformations of the molten pool contour. The adverse effect of the inlet or nozzle is taken into account. Experimental measurements were conducted, and the results indicate that a single camera can accurately measure the molten steel level. Potential sources of error or limitations that may impact the accuracy of the proposed method is discussed.

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: A scraper was attached to an unequal-diameter twin-roll caster without requiring large modifications. This caster was used as a 1000 mm diameter single roll caster equipped with a scraper, and its strip casting ability was tested. The effects of the scraper angle and load, the roll speed, and the pouring temperature of the molten metal on the scribed surface, thickness distribution and average strip thickness were investigated. The scribed surface characteristics were sound and the thickness distribution was flat when the scraper angle was 60° and the scraper load was in the range of 1 to 4 kg. When the scraper load was more than 1 kg, the thickness distribution was uneven. The average strip thickness decreased as the roll speed increased. The pouring temperature of the molten metal influenced the evenness of the solidified layer thickness. The solidified layer became even as the molten metal temperature was decreased. A strip cast with the determined optimal conditions was then cold rolled down to 1 mm to improve its surface quality.

Abstract: Fe-6.5wt%Si steel is an excellent soft magnetic material due to the near-zero magnetostriction and low core losses. In this study, a 0.3 mm-thick grain-oriented 6.5wt%Si steel sheet was produced by a novel strip casting and two-stage rolling. The microstructure and texture evolution were investigated with a special emphasis on the nucleation and growth of Goss grains. The thin normalized strip was composed of large columnar grains and small equiaxed grains. During intermediate annealing, Goss grains nucleated in the shear bands of the deformed <111>//ND grains, and the deformed {111}<112> grains provided most of the nucleation sites. After primary annealing, the Goss grains distributed across the entire thickness, which was different from the conventional rolling route. The fraction of high-angle boundaries (20°-45°) surrounding the Goss grains was apparently higher than those of the matrix grains, which promoted the abnormal growth of the Goss grains during secondary recrystallization.

Abstract: Strip casting is a new method of producing metal matrix composites. Two-roll melt dragged processing (TRMD-ing) and single-roll melt dragged processing (SRMD-ing) methods were used to study the manufacture of 2-mm-thick composite strips by using PbSn (≈ 11.3 g/cm³) eutectic alloy matrix reinforced with iron (≈ 7.86 g/cm³) powder (≈ 70 μm) at a rate of 0.3 m/s. The metallic powder stored in the feed hopper (≈ 90 g) was pushed during the pouring operation of the cast alloy (≈ 4 kg) at 260 oC on the cooling slope to produce a mixture of metallic slurry and particles to feed the nozzle to be dragged by the lower roll. Various surface defects occurred during processing, such as the failure of the powder particle to be embedded in the matrix by SRMD-ing with and without stirrer into the nozzle, and the rolling up of the strip into the nozzle by TRMD-ing. Graphite nanoparticles formed inside the α-Pb grain revealed a complicate eutectic structure in both the processing methods. The colloidal graphite used to coat the crucible, cooling slope, and nozzle could act as a nucleation agent for preferential centre segregation in the α-Pb grain. This suggests that the graphite nanoparticles functioned as nucleation points in the lead-rich α phase. Thus, another type of composite was formed in the presence of graphite nanoparticles within the lead-rich α-phase surrounded by β-Sn. An electron probe microanalysis and scanning electronic microscopy were used to investigate the composition and distribution and identify the different phases. Several types of particulate reinforcements may be added to the matrix to obtain composites for mechanical, electronic, and magnetic applications using these technologies.

Abstract: Among the problems encountered when roll casting Al-405Sn-1%Cu, which is an aluminum alloy used for sliding plate bearings in large maritime diesel engines, are solidified chips embedded in the strip and scratch marks on the lower roll contact surface. In this study, three different improvement methods aimed at eliminating these particular defects—vibrating the side plates and back dam plate, adding a vibrating plate, and varying the casting conditions—are examined. Vibrating the side plates and dam plate was found to be effective for preventing these defects, while adding another vibrating plate was comparatively less effective. As for casting conditions, it was also determined that the occurrence of these defects could be reduced by increasing the roll speed, and that the molten metal casting temperature had little or no influence on defect formation.

Abstract: Strip casting of Al-40%Sn-1%Cu, which is an aluminum alloy used for sliding bearings, was attempted using an unequal diameter twin roll caster. The conditions required to cast sound strips, including the roll speed, molten temperature, roll load, solidification length, melt head, and use of an upper plate, were investigated. The roll load required to make a stable strip surface was 0.01 kN/mm, and the porosity was minimum when the solidification time was less than 0.6 s. The solidification time was controlled by the roll speed and the solidification length. The casting temperature must be set below 670°C to properly solidify the molten metal, and the metal microstructure became finer as the melt head decreased.

Abstract: An unequal diameter twin-roll caster equipped with a channel scraper is proposed to improve center-line segregation. A semisolid metal layer was made by the channel scraper on the upper side of the strip and solidified by an upper roll. The twin-roll caster cast a strip of 5182 with equiaxed grain and without center-line segregation at a speed of 30 m/min and a unit roll load of 104 N/mm. The tensile stress and elongation after cold rolling and annealing were 294 MPa and 28%, respectively.

Abstract: This paper describes a production process for aluminum alloy sheet metal. Direct molten metal rolling, in other words strip casting process for aluminum alloy A3003 sheet was operated. Strip casting process is able to produce the metal sheet from molten metal directly. Thus this process has possibility of improving the productivity of sheet because of shortening operation of rolling. In this study, experimental device was designed for direct molten metal rolling. Aluminum alloy A3003 was chosen. A3003 is for aluminum can body, and the sheet required the high productivity. The effect of roll speed on the produced strip surface and strip thickness was investigated. Roll speed were 1, 2 and 3 m/min. It was possible to produce A3003 strip by direct rolling at the conditions of roll speed 3 m/min, pouring temperature 700 °C, solidification length 15 mm and nozzle exit width 15 mm. Obtained strip surface was flatten and had a metallic luster.