Analysis and Improvement of Nozzle Clogging of Ti-bearing Welding Wire Steel

Abstract

The element content， phase composition and interface reaction of nozzle clogging for titanium-bearing welding wire steel SJ-60 during continuous casting were analyzed by means of XRF， XRD and SEM. It is found that the interface of the nozzle is rough and porous due to decarburization reaction， which causes nozzle to be easily invaded by high melting point phases. In addition， the calcium treatment and erosion of refractory during the refining process will produce a large amount of CaTiO3 and MgAl2O4 in the molten steel， and the deposition of both at the interface of the nozzle is the main cause of nozzle clogging. The practice has shown that replacing ordinary ferrosilicon with low titanium and low aluminum ferrosilicon can reduce the aluminum content in steel from 0.008 0%~0.009 5% to 0.005 0%~0.006 5%， which is beneficial for reducing the content of Al2O3 inclusions in steel. Cancelling the refining calcium treatment can reduce the calcium content in steel from more than 0.001 4% to less than 0.000 5%， which is beneficial for reducing the content of CaTiO3 inclusions in steel. Reducing the amount of fluorite from 0.8~1.0 kg/t to 0.3~0.5 kg/t can reduce the erosion of refractory， and the magnesium oxide content in slag is decreased from more than 10% to less than 5%， which is beneficial for reducing the content of MgAl2O4 inclusions in steel. Through the above measures， the problem of nozzle clogging caused by CaTiO3 and MgAl2O4 has been effectively solved，and the number of continuous casting heats is increased from 4-5 heats to more than 12 heats.

Keywords

• titanium-bearing welding wire steel； nozzle clogging； calcium titanate； spinel； titanium nitride