Analysis of the nonuniform slag film, mold friction, and the new cracking criterion for round billet continuous casting

Abstract

A method predicting the thickness of solid and liquid slag films is presented to understand the complicated heat transfer from the strand to mold for round billet continuous casting. A mathematical model is also developed to calculate the liquid slag lubrication and solid slag friction on the basis of mechanics of viscous fluids and the contact state between the solidifying shell and mold. And a new criterion, based on the nonuniformity of mold heat transfer around the perimeter is proposed to predict the longitudinal crack. The results show that in the upper mold the distribution of the thickness of liquid slag film is similar with that of the solid one, and both of them are nonuniform around the mold perimeter, so does the mold friction. Increasing the casting speed could advance the time of crack formation for one casting process. By comparison, the sensitive area of the longitudinal crack predicted by the new criterion corresponds to that by a stress-based crack criterion. It may lay the theoretical foundation for the on-line detection of billet quality and the visualization of the continuous casting mold process.

Performance of a Nozzle to Control Bath Level Oscillations and Turbulence of the Metal-Flux Interface in Slab Molds

“…The uncontrolled liquid flow near the metal-flux interface will usher powder entrainment to become trapped particles in the solidified shell. Non-melted powder induces sticking breakouts and bath level oscillations to promote transversal slab depressions and strand breakouts [3][4][5][6]. The literature in the field dealt with the effects of nozzle immersion depth, casting speed, steel grade, and thermo-solute convection on the fluid patterns of liquid steel in slab molds [7][8][9][10][11][12].…”

Investigation of Friction Force between Mould and Strand Shell under Sinusoidal and Non‐sinusoidal Oscillation in Continuous Slab Casting

“…The working force is calculated from the pressure difference between the inlet and outlet of the main hydraulic cylinder, which supports mould assembly during oscillating. The difference in working force during casting and idling periods at the same parameters is expressed as the friction force, which is a widely recognized method [5,[12][13][14]. So the friction force can be calculated by equation (I).…”

Initial Solidification and Its Related Heat Transfer Phenomena in the Continuous Casting Mold

“…There are several factors to influence breakouts in the casting process. The first one is the mold flux . The mold flux with high melting temperature and low melting rate cannot generate sufficient liquid to fill the shell/mold gap, thus the lubrication of the initial shell would be deteriorated, especially during the positive stripping time when the initial shell is continuously drained by the mold oscillation.…”