Titanium Carbides Precipitation Characteristics and Influence on Hot Ductility in 0.37 pct Ti–Mo Slab During Continuous Casting

Multiscale titanium carbides are one of the main causes of corner crack defects of 0.37 pct Ti–Mo steel slab. In this work, the evolution of titanium carbides precipitation under different cooling rates were investigated by high-temperature laser scanning confocal microscopy, transmission electron microscope, and thermal simulation. The research revealed that micron TiC particles are derived from eutectic reactions at the end of solidification which are divided into dendritic TiC and lamellar TiC according to the precipitation order. According to Thermo-Calc simulation, the titanium elements play a leading role on the titanium-carbide/γ interface movement. Nano-(Ti,Mo)C are mainly precipitated from the high-temperature austenite after solidification. The micrometer TiC is gradually broken and refined, and the distribution is transferred from grain boundary to grain interior with the increase of cooling rate. High cooling rate can reduce the production of micron TiC but promote the formation of ferrite film and destroy the hot ductility.