The mould is the heart of the continuous casting process.
Its main function is to establish a solid shell sufficient in strength to
support its liquid core upon entry into the secondary spray cooling zone. Mould
oscillation is necessary to minimize friction and sticking of the solidifying
shell, and avoid shell tearing, and liquid steel breakouts. Oscillation needs to
be established. Low friction between the shell and mould is pursued through the
use of mould lubricants.
Mould designs and operating practices have a major effect on:
Defects created in the mould are very difficult to correct later. High performance requires complex
optimization of metal delivery, lubrication, and mould design.
Comprehensive reviews of mould modeling activities have been published recently.
An overview of how mathematical modeling has contributed to caster performance in the mould
is provided as follows.
Controllable Parameters
Casting Practices
Casting speed
Superheat
SEN design, submergence
Flow controls
Argon injection
Mould powder selection
Oscillation patterns
Sequence casting practices Mould Designs
Geometry, shape, taper
Materials
Internal cooling
Electromagnetic stirrer/brake
Oscillation system
Mould Designs
Geometry, shape, taper
Materials
Internal cooling
Electromagnetic stirrer/brake
Oscillation system
Modeling Contributions
Mould powder melting; effects of chemistry and process
Removal of superheat from the liquid, latent heat of fusion, and the
sensible heat (cooling below the solidus temperature)
Heat transfer (convection, conduction and radiation), especially between steel and mould
Deformation of initial shell and liquid flux pressures
Fluid flow in the mould; bubble dispersion; inclusion tracking; chemical
mixing
Heat transfer, shrinkage and stress in solidifying shell
Heat transfer and stress in mould walls
Fluid flow and electromagnetic fields; temperatures near meniscus;
inclusion distributions
Dynamics of oscillation, starter bar and mould structures
Application Benefits
Flux thickness prediction
Powder design and selection
Reduced breakouts
Instrumented moulds
Reduced oscillation mark depths; oscillation guides
Optimized SEN designs
Improved surface and internal quality; inclusions, flux, argon
Grade transition practices
Mould taper design
Reduced mould wear
Improved mould designs; water cooling, constraints
Improved surface quality; depressions, cracking
Increased casting speeds
Reduced flux entrainment with electromagnetic braking
Reduced inclusions and pinholes with electromagnetic
Improved starter bar design and maintenance
References
[1] J.K. Brimacombe and A.W.Cramb: Steelmaking, casting and modelling.
Proc. 10th PTD Conf., ISS, Toronto, April 1992
[246] ASM: Modeling in Welding, Hot Deformation and Casting. 1997. ISBN
0-87170-616-4. Ed. By L. Kalsson.
[247] J. Herbertson and P. Austin: The Application of Mathematical Models for
Optimisation of Continuous Casting. Modeling of Casting, Welding and Advanced Solidification Processes - VI. Proceedings. TMS 1993. ISBN 0-87339-209-4.
