1994 Volume 80 Issue 9 Pages 717-722
Casting tests of stainless steel type 304 was carried out by a twin-roll type strip caster, which is one of possible technology to produce thin strips from molten metal directly.
The main problem to be solved was surface defects of strips, such as longitudinal cracks, transverse cracks and small depressions. And these defects were overcome in this study.
Uniform growth of solidified shell is most important to reduce longitudinal cracks and small depressions. By water model experiments, the best pouring conditions were obtained. They present uniform feeding rate along the width ofstrips and small meniscus level fluctuations by optimizing pouring position, ratio of the molten steel weight on the twin rolls to the pouring rate and fall height of molten steel from a tundish to twin rolls.
On the other hand, small reduction of the cast strips is important to reduce transverse cracks. First, in order to control this, heat transfer coefficient between rolls and solidified shell was estimated by measuring temperature of strips, rolls and cooling water of rolls. And the best casting condition, where solidification ends just at the closest point of twin rolls, was calculated by using this heat transfer coefficient.
