1997 Volume 37 Issue 4 Pages 375-382
Preventing crack formation of solidifying steel shell at increasing speed in continuous slab casting operation is a prerequisite to increase the ratio of hot charge rolling and hot direct rolling of cast slabs. Crack formation is influenced by mechanical properties of the steel shell near its solidus temperature. Thus, fracture strength of solidifying steel shells containing 0.004 to 0.70 mass% C has been measured in-situ by using a method similar to "Submerged Split Chill Tensile (SSCT)" test by Ackermann, Kurz and Heinemann. The fracture strength at an early stage of solidification, when the shell thickness is 2 to 5 mm, has been found to be 1 to 3.5 MPa which is lower than that determined by conventional hot tensile tests, since the crack initiates at and propagates in interdendritic region in the shell in the in-situ SSCT test. Comparing the fracture strength of the shell with the frictional force at the shell/mold interface, upper limit of casting speed of slab caster is calculated to be around 8.5 m/min.
