A theoretical calculation has been made of bulging as a major cause of internal cracks arising in the secondary cooling zone in strand cast slabs. Temperature distribution in the solidifying shell has preliminarily been determined from a heat transfer model, then an elastoplastic stress analysis of the shell has been made in terms of the finite element method.
A quantitative evaluation of the influence on bulging has been carried out of the withdrawal rate, spray water flux, pitch between rolls and disorder in the alignment of rolls, leading to an effective means to prevent bulging under high withdrawing rate condition. Factors influencing the critical bulging strain beyond which internal cracks develop are also discussed.