Prevention of Slab Surface Transverse Cracking by Microstructure Control

Effect of Cooling Rate on the Precipitation Behavior of Carbonitride in Microalloyed Steel Slab

“…According to Eq. [1], [14] the size of precipitates is a function of the square root of the nucleation time, where t c is the cooling rate, KAEs À1 ,R p is the radius of the precipitation particle, nm;, k is the growth rate constant of precipitations, dimensionless, and D is the diffusion coefficient of elements, cm 2 s À1 . According to the classical Avrami empirical shown in Eq.…”

“…However, the effect of applying this method is not practical. Recently, Kato et al [1,2] has managed to prevent the surface transversal cracking of continuous casting microalloyed steel through the control of the slab surface microstructure cooling. In this method, slab surface microstructure correlates with the precipitation behavior of carbonitrides in the microalloyed slab, and the precipitation behavior is controlled by the cooling rate.…”

Effect of Cooling Rate on Phase Transformation and Microstructure of Nb–Ti Microalloyed Steel

“…7) And different cooling rates also result in the formation of different microstructures. 8,9) Therefore in this paper in situ observation equipment of a confocal laser scanning microscopy (CLSM) and a Geeble-3800 thermal simulation machine were used to investigate the effect of cooling rate on phase transformation and microstructure of NbTi microalloyed steel. And it was found that the formation of the proeutectoid ferrite along the austenite grain boundaries was closely related with the precipitation of carbides and/or nitrides along the grain boundaries.…”

Assessment of Hot Ductility with Various Thermal Histories as an Alternative Method of in situ Solidification

“…[1][2][3] There has been much work to reduce these defects through various methods, such as control of the chemical composition of steel, surface structure control of the slab, and hot deformation on cooling. [4][5][6][7][8] Several experimental methods have been adopted to simulate the continuous casting process more precisely, inducing fatigue deformation on cooling, in situ solidification tensile tests, and tensile tests in an air atmosphere. 1,[7][8][9] Among these methods, the in situ solidification tensile test has been known as the best tool to simulate the continuous casting process because this method could carry with it stress development and solidification cracking during solidification.…”

“…[4][5][6][7][8] Several experimental methods have been adopted to simulate the continuous casting process more precisely, inducing fatigue deformation on cooling, in situ solidification tensile tests, and tensile tests in an air atmosphere. 1,[7][8][9] Among these methods, the in situ solidification tensile test has been known as the best tool to simulate the continuous casting process because this method could carry with it stress development and solidification cracking during solidification. However, in situ solidification tensile tests also have some drawbacks, i.e., void formation on solidification and interface phenomena between the mold wall and the specimen, which are perpetual experimental problems.…”