Kazuya Akitsu

Strip Casting by a Single Roll Caster Equipped with a Scraper

A scraper was equipped to a single roll caster to improve the free solidified surface. The scraper contacted to the free solidified surface at the constant force. The some mount of semisolid layer at the surface 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 by the plate. 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. The AA5182 and AA6022 aluminum alloy were cast. The as-cast strips could be cold rolled. The microstructure of as-cast strip was not uniform at thickness direction. However, the microstructure became uniform after the cold rolling and the annealing.

Single Roll Caster Equipped with a Scraper

A scraper was developed and attached to the single roll caster in order to improve the free solidified surface of as-cast strip cast. Semisolid metal on the free solidified surface was flattened by the scraper and the surface became flat. The AA5182 aluminum alloy could be cast at speeds up to 40m/min. Thickness was about 3mm. Pressure of the unit width of the scraper was ranging from 0.1N/mm to 1.0N/mm, and these pressure was enough to make the free solidified surface flat. Center line segregation did not occur as the strip was solidified from single side at the strip cast by the single roll caster. Roll-cast strip could be cold rolled down to 1mm. There was not difference between the roll contact surface and the free solidified surface of the strip after cold rolling judging by a visual examination. Result of tension test of the roll cast and cold rolled strip was as same as that of D.C. cast and rolled strip. Deep drawing test was operated at the conditions both of the roll contact surface and the free solidified surface were outer side. LDR (limited drawing ratio) was same at both conditions and they were 1.8. Thickness of the strip was controlled by the roll speed, solidification length (length of the melt pool) and pressure of the scraper. The single roll caster is simpler than a twin roll caster. Rigidity for rolling was not required for the single roll caster. Cost of the roll is half comparing a twin roll caster. The equipment cost of the single roll caster is more economy than that of the twin roll caster.

A Single Roll Caster for Aluminum Alloy Strip

Single roll caster to cast strip with sound free solidified surface was invented. A scraper was attached to the single roll caster to improve the free solidified surface. AA5182 and AA6022 strips were cast using the single roll caster equipped with the scraper. Mechanical properties of the strip were investigated by tension test, bending test and deep drawing. Mechanical properties of the strip cast by the single roll caster were as same as those made by DC casting.

Improvement of Free Solidified Surface of Strip Cast Using a Single Roll Caster by Scribing Semisolid Layer

AA5182 alloy was cast using the single roll caster equipped with the scraper. Improvement of flatness of the free solidified surface of the strip cast by a single roll caster was tried by scribing of semisolid layer using a scraper. The semisolid layer could be scribed and be made flat by the scraper. The scribing force was controlled by a dead weight. Defects which occurred on the scribed surface were investigated. The property of the free solidified surface (scribed surface) was compared with roll contact surface by the deep drawing test. The property of the scribed surface was almost as same as that of the roll contact surface. Mechanical property was investigated by the tension test.

Casting of aluminum alloy strip by a single-roll caster equipped with a scraper

A SRCES(Single-Roll Caster Equipped with a Scraper)was devised in order to improve the free-solidified surface. A scraper contacted to the free-solidified surface at the constant force. The some amount of semisolid metal on the solid layer was removed and the surface condition becomes flat. The melt pool was mounted on the top of the roll. Therefore, the scraper was easily operated. In our study, aluminum alloy strip was cast by the SRCES. The scraped surface condition of the cast strip was investigated. The as-cast strip could be cold-rolled and the roughness of the free-solidified surface was reduced. There was no difference between the free-solidified surface and roll-contact surface after cold-rolling. The cross-section of the as-cast strip was observed. The porosity of the free-solidified surface was less than the porosity at center area of the strip cast by a TRC(Twin-Roll Caster). The mechanical properties of the cast strip were investigated by deep-drawing test and tensile test. As a result of deep-drawing test, there was no difference between the free-solidified surface and the roll-contact surface after cold-rolling. As a result of tensile test, mechanical properties of cold-rolled strips were similar to the strip cast by the D.C.casting. These result shows that the free-solidified surface could be improved up to the roll-contact surface by the scraper and cold-rolling. (Received September 20, 2011 Accepted January 12, 2012)

Single Roll Caster to Cast Aluminum Alloy Strip

A scraper was developed and attached to a single roll caster to improve the free solidified surface of the as-cast strip. AA5182 aluminum alloy of thickness approximately from 1.5mm to 4 mm was cast at speeds up to 60 m/min. With the scraper, semisolid metal on the free solidified surface was flattened. The pressure of the unit width of the scraper ranged from 0.1 N/mm to 1.0 N/mm and was sufficient to make the free solidified surface flat. Because the strip was solidified on a single side by the single roll caster, center line segregation did not occur. The roll cast strip could be cold rolled down to 1 mm. Visual examination after cold rolling showed no difference between the roll contact surface and the free solidified surface of the strip. The results of tension tests of roll cast and cold rolled strips with the scraper were the same as those of direct chill (DC) cast and rolled strips. A deep drawing test was conducted under two conditions: the roll contact surface was on the outer side, and the free solidified surface was on the outer side. The limited drawing ratio of 1.8 was the same for both conditions. The thickness of the strip was controlled by the roll speed, solidification length (length of the melt pool), and the scraper pressure. The utility of the scraper was shown by the casting of 600 mm width strip. This single roll caster could cast the strip of Al-10mass%Mg which is seemed to be difficult to cast strip without the center segregation by the twin roll caster. The single roll caster is simpler than a twin roll caster. The rigidity for rolling is not a significant concern for the single roll caster. In addition, since the cost of the roll is half that of a twin roll caster, the equipment cost of the single roll caster is more economical.

Roll Casting of Aluminum Alloy Strip by a Single Roll Caster Equipped with a Scraper

A single roll caster equipped with a scraper was devised to cast the strip with sound free solidified surface. A property of this single caster is equipment of the scraper. Semisolid metal on the free solidified surface was scribed by a scraper and the surface became flat. Center line segregation did not occur as the strip was solidified from single side. The AA5182 aluminum alloy could be cast at speeds up to 40m/min. Thickness was about 3mm. Pressure of the unit width from the scraper was ranging from 0.1N/mm to 1.0N/mm, and these pressure was enough to make the free solidified surface flat. Roll cast strip could be cold rolled down to 1mm. There was not difference between roll contact surface and the free solidified surface after cold rolling by a visual examination. Result of tension test of the roll cast strip was as same as that of D.C. cast and rolled strip. Deep drawing test was operated at the conditions both of the roll contact surface and the free solidified surface was outside. LDR (limited drawing ratio) was same at both conditions and they were 1.8. Thickness of the strip was controlled by the roll speed, solidification length (length of the melt pool) and pressure of the scraper. The single roll caster is simpler than a twin roll caster. Rigidity for rolling was not needed for the single roll caster. Cost of the roll is half comparing a twin roll caster. The equipment cost of the single roll caster is more economy than that of the twin roll caster.

Casting of Aluminium Alloy Strip by Improved Single-Roll Caster

A scriber was equipped to a single roll caster to improve the free solidified surface. The scriber contacted to the free solidified surface at the constant force. The some amount of semisolid layer at the surface was removed and the surface became flat. The scriber was made from the mild steel plate. The mild steel plate was covered by the insulator paper to prevent the cooling of the melt by the plate. The melt pool was made on the roll by the side dam plates, back dam plate and the scriber. Therefore, a tip or a nozzle was not needed. The AA5182 and AA6022 aluminum alloy strip were cast by single roll caster with scriber. The as-cast strips could be cold rolling. The microstructure of as-cast strip was not uniform at thickness direction. However, the microstructure became uniform after the cold rolling and the annealing.