Abstract
The macro structure and the segregation of continuously cast carbon steel billets with 80 to 250mm square and 260×370mm in section were investigated. The results were summarized as follows.
1. The length of columnar crystal and the thickness of central segregated zone are increased, and the central porosity and segregation become worse, with increase of superheated casting temperature.
2. The absolute thickness of central segregated zone is increased with increase of the section of square billet, but its relative value to billet thickness is decreased. The type of V segregation is changed from single V line to multi V line, in the case of high superheat temperature.
3. The type of V segregation is changed from V line to V zone and the central segregation disappear, when the billet shape is changed to rectangular.
4. The maximum positive segregation ratios of Mn and C are 1.3 and 1.8 respectively, which are obtained by the analysis of specimen with 3 mm in dia and 3 mm in depth taken from the central segregated zone high carbon billet with 160 mm square in section.
5. The length of columnar crystal and the width of central segregated zone are increased in the order 0.3%C, 0.1%C and 0.6%C steel under the same condition of super heated casting temperature.
6. The mechanism of formation of equiaxed dendrite and V segregation are discussed.
