Continuous casting of Bi-Pb and Bi-Pb-Sn thermal fuse alloys by the Ohno Strip Casting process

The OSC apparatus has been constructed and used to examine the feasibility of continuously casting thermal fuse alloy strips. Cast surface quality of the strips, solid-liquid interface position and casting parameters such as casting speed, withdrawal angle and cooling conditions have been studied using Bi-45%Pb, Bi-44%Pb-1%Sn, and Bi-32%Pb-16%Sn alloys (all in mass%). It was confirmed that 2 mm thick and 50 mm wide strips could be produced by the OSC process. In order to maintain stable casting, the solid-liquid interface position must be located no closer than 0.5 mm from the cooling water. It was found that the solid-liquid interface position was closely related to the temperature and amount of cooling water. It was also found that the withdrawal angle of the strip must be kept slightly upward in order to obtain a good surface finish on the strip.