The Control Application And Basic Research On The Clogging Of Tundish Nozzle For Ti-ULC Steel

Because of the soft demand for the steel market, iron and steel companies earn very little money. In order to improve the product competitiveness, enterprises need to improve efficiency and technology. SEN is like a hub contacting the tundish and the crystallizer whose quality influences continuous casting a lot. High quality SEN has a long life and doesn`t get clogging easily which is the key to high quality billet.The longevity of SEN depends on clogging and corrosion. In order to study the reason for clogging and improve longevity, research was done to SEN after it pouring steel for four tundishes continuously. The SEN is cut into 8 pieces, SEM-EDS and XRD are used to analysis the phase composition and microstructure for different position of nozzle clogging. Along with the analysis results for the inclusion in the mold, the results for the nozzle clogging and erosion of the refractory are obtained. Wetting angle measurement is used to measure the contact angle between Al₂O₃ substrate and different types of steel. The nozzle clogging can be alleviated by doing research for the wettability of the clogging materials.The results are as follows: The thickness of the nozzle clogging is less than 5mm and the position near outlet get clogging seriously. Most of the clogging materials are Al₂O₃ inclusions below the slag line. Al₂O₃? Fe Al2O4 and magnesium aluminate spinel inclusions are found near the slag line. The clogging material near the skateboard is solidification steel which is caused by low temperature. The density of the inclusions in the billet is 14.1/mm² after been converted to 7.5?m inclusions. The main ingredients of the inclusions are Al₂O₃-Ca S?pure Al₂O₃ and complicated Al₂O₃-Mg O-Ca S-Mn S. There are some inclusions containing Ti which in accord with the clogging materials in the SEN. The size of the Al₂O₃ is between 1.5?3.5mm after adding Ti to ULC steel. Nozzle clogging keeps aggravating with the increasing content of Ti in the liquid steel. The contacting angle of Ti-ULC steel and Al₂O₃ substrate is 127.6° under 1550?, and with the increase of Ti density in the ULC steel, the contact angle decline gradually.