Effect of Li 2O addition on crystallization behavior of CaO-Al 2O 3-MgO based inclusions

Abstract

The crystallization behavior of CaO-Al 2O 3-MgO oxide powder which is one of the major non-metallic inclusions in Al-killed steel was systematically examined in the present study. 33mass%CaO-62mass% Al 2O 3-5mass%MgO and 30mass%CaO-57mass% Al 2O 3-5mass%MgO-8mass%Li 2O glass powders were heat-treated at 1 073-1 673 K for 8-512 s under air. CaO-Al 2O 3-MgO glass was found to be crystallized immediately after the heat treatments. Moreover, it was revealed that the addition of Li 2O accelerated the crystallization of the glass powders, and controlled aggregation of crystal particles. Additionally, the indentation hardness of crystallized glasses after 512 s heat-treatments was investigated by using a nano-indenter. The addition of Li 2O had the effect of lowering the hardness of samples, which indicates that Li 2O would improve the deformation behavior of aluminate based inclusions. © 2011 ISIJ.