Abstract: Low-carbon microalloyed steel was produced via twin-roll strip casting in the laboratory. The solidification structure， microstructure at room temperature， precipitate and dislocation of the as-cast strip were analyzed by OM， SEM and TEM. The results showed that the secondary dendrite arm spacing of the solidification structure is in the range of 12~15μm， which is much finer than that of the slab produced by the traditional process. The prior austenite grain of the as-cast strip is quite coarse with a size range of 250~410μm. The microstructure of the as-cast strip consists of Widmanstatten ferrite， pearlite and irregular ferrite. The nano-sized TiC precipitate and rod-like cementite are observed in the as-cast structure. The TiC precipitate in the as-cast strip is not obviously suppressed by the rapid solidification rate and secondary cooling rate (cooling in air) of the twin-roll strip casting. Furthermore， a large amount of dislocations in the as-cast strip are also observed， formed by rolling force among the casting rollers and nonuniform cooling rate of the second cooling process.

Key words: twin-roll strip casting, low-carbon microalloyed steel, solidification structure, prior austenite grain, precipitate