Effect of Hot Rolling Conditions on Annihilation of Porosities in Continuous Casting Slabs

Abstract

Effects of hot rolling parameters on the annihilation of porosities in continuous casting slabs or ingots were investigated using specimens which include artificial porosities (sphere and cube). It was revealed that, of hot rolling parameters, the reduction ratio and the rolling shape factor are essential factors for the annihilation, whereas the rolling temperature is less influential. The following formulae was derived to predict the rolling conditions required for the annihilation of porosities.
d₀H_k/H₀-∑^k_j=1H_k/H_jω₀(C₀+C₁m_j+C₂m²_j)≤0, m_j=2√R(H_j-1-H_j)/(H_j-1+H_j) (j= 1, 2, ......k)
where d₀, ω₀ : initial porosity size of thickness and width respectively, j : index of rolling pass schedule, H_j : plate thickness after j-th rolling pass (H₀ : initial thickness), R : radius of work rolls, c₀, c₁, c₂ : constants.