Interfacial Reaction Between Inclusions in Molten Steel and Refractories for Continuous Casting

摘要

In this study, we chose a newly developed MG material with low thermal expansion and an AG material commonly used for bore walls of continuous casting nozzles as test samples, and we conducted a dynamic erosion/corrosion test under molten steel flow simulating Ca treated steel and Hi-Mn steel, and also a static, wettability evaluation test. We further investigated an interfacial reaction between the inclusions in molten steel and the refractories and evaluated their erosion/corrosion characteristics and mechanism, and our conclusions are as follows: (1) In the erosion/corrosion test simulating Ca treated steel, the MG exhibited excellent erosion/corrosion resistance and its erosion/corrosion rate was 1/2 or lower of that of AG (2) In the erosion/corrosion test simulating Mn steel, the MG also exhibited excellent erosion/corrosion resistance and its erosion/corrosion rate was approximately 1/3 of that of AG. (3) CA slag had a higher wettability with Al_2O_3 than MgO, and it also had a higher reactivity with Al_2O_3. (4) The composition of reaction layer in the dynamic test was smaller than that in the static test, and it was approximately 1/5 of the latter. (5) The erosion/corrosion phenomenon of refractories in an actual casting progresses in the following process: inclusions in molten steel and refractories contact and react on their interface, a slag layer flows down along with molten steel flow at some frequency, and a new hot surface is exposed, and the process is repeated. (6) Therefore, the dynamic test method simulating the molten steel flow in this study could be an evaluation method closer to actual casting condition. (7) Although the application of MG materials to continuous casting nozzle is generally restricted due to its high thermal expansion, the MG material used in this study achieved both erosion/corrosion resistance and thermal spalling resistance, therefore its application to continuous casting nozzles is anticipated.