Determination of CC slab solidification using nail shooting technique

Microscopic dendritic morphology and central macrosegregation in continuously cast high carbon steel billets with a cross section 150 Â 150 mm 2 are investigated to elucidate their effect on the microstructure and mechanical property of the following hot-rolled wire rods, whose diameters are 10 and 6.5 mm, respectively. Experimental observations and numerical simulations for the steel billets under different casting conditions are carried out. It is found that the secondary dendrite arm spacing (SDAS) in the billets increases with the increase of superheat temperature, while decreases with the increasing specific water flow. Smaller SDAS in the billet center leads to lower segregation index of carbon (r C ) and manganese (r Mn ) due to the low permeability in the final solidification stage. The measured r Mn and r C in billets are in an approximately linear relationship. In addition, for the same rolling and cooling process, the severer carbon segregation in the center of the billets is, the lower the sorbite rate of the rods and the worse stability in the mechanical property of the rods. The tensile strength of wire rods can be improved by adjusting the casting parameters to decrease the SDAS and reduce the central carbon segregation of the billets.

d = K \sqrt{t}

where d is the shell thickness.…”

Section: Methodsmentioning

confidence: 99%

Effect of Dendritic Morphology and Central Segregation of Billet Castings on the Microstructure and Mechanical Property of Hot-Rolled Wire Rods

Yuan

Tang

Peng

et al. 2017

“…When accurate pyrometer measurements are available, an inverse model can be applied to match the predicted surface temperature profile with the peaks of those measurements, to overcome dips caused by intermittent scale . Finally, the shell thickness predictions near final solidification of several models have been successfully validated with nail shooting measurements …”

Section: Heat Transfer and Solidificationmentioning

confidence: 99%

Review on Modeling and Simulation of Continuous Casting

Thomas

2017

175

115

Continuous casting is a mature, sophisticated technological process, used to produce most of the world's steel, so is worthy of fundamentally-based computational modeling. It involves many interacting phenomena including heat transfer, solidification, multiphase turbulent flow, clogging, electromagnetic effects, complex interfacial behavior, particle entrapment, thermal-mechanical distortion, stress, cracks, segregation, and microstructure formation. Furthermore, these phenomena are transient, three-dimensional, and operate over wide length and time scales. This paper reviews the current state of the art in modeling these phenomena, focusing on practical applications to the formation of defects. It emphasizes model verification and validation of model predictions. The models reviewed range from fast and simple for implementation into online model-based control systems to sophisticated multiphysics simulations that incorporate many coupled phenomena. Both the accomplishments and remaining challenges are discussed.

“…The simulating conditions are as follows: the casting section is 250 × 2270 mm, and the casting speed is 0.9 m · min −1 , the simulation that did not take into account the cooling difference in width direction of the slab was based on the average flow density in each cooling zone. The measured temperature of the slab is obtained by a hand‐held infrared thermometer, and the shell thickness of 1/8 width of the slab is measured by the pin shooting method on the continuous caster . It should be noted that duration of temperature measurement at each location is 3 min, and the highest temperature measured in 3 min is adopted as the surface temperature.…”

Section: Industrial Application Of the Three Dimensional Temperature mentioning

confidence: 99%

Research on the On‐Line Simulation of a Three‐Dimensional Temperature Field Model of Slab Continuous Casting

Kong

Chen

Liu

et al. 2018

Based on the two-dimensional heat transfer and solidification model, the differences in heat transfer boundary conditions in the casting direction and width direction of a slab are researched, and the results are verified by experiment. By using the method of "limited thickness slice unit", the numerical discretization of each slice unit in the computational domain space is carried out in real time, and the casting information of all the slice units in the slab is tracked in real time, which achieves the effect of a three-dimensional temperature field simulation model. Through the double process program, the three-dimensional temperature field on-line simulation model calculation cycle meets the on-line control requirements. The three-dimensional temperature field on-line simulation model is successfully applied in a domestic steel mill to the 4th slab caster. The secondary cooling dynamic water model and dynamic soft-reduction model based on the three-dimensional temperature field are used to modify the original model. After modification, the qualified rate of crack detection feedback from rolling is improved by 1.4%, and the qualified rate is basically stable at approximately 99.5%. The incidence of transverse cracks, longitudinal cracks, and corner cracks on the slab surface decreases by 53.96%, 56.3%, and 29.19%, respectively.