Microstructure Evolution during Hot Rolling of TA1 Slab Produced by EB Furnace Smelting

The influences of hot rolling deformation temperature and single pass reduction rate on the microstructure evolution and recrystallization of EB furnace slab during hot rolling were studied by hot rolling experiments and microstructure observation.It is found that the grain size of EB furnace slab is hundreds of times larger than that of VAR forging slab after heating the slab before hot rolling,and the coarse grain structure of EB furnace slab is not conducive to recrystallization during hot rolling.By increasing the rolling temperature（≥ 850 ℃）,reducing the single pass reduction and decreasing the hot rolling deformation speed,the hot rolling structure can be fully recrystallized.The high-temperature start rolling,high-temperature finishing rolling and high-temperature coiling of thin slab were discussed to obtain a large proportion of recrystallization structure of the hot rolling coil,so that the traditional annealing recrystallization process of hot rolling plate can be omitted.It is found that when the hot rolling temperature is 850 ℃,there is a critical reduction rate（43.6%） for refining recrystallized grains.When the reduction rate is lower than 43.6%,increasing the reduction rate can significantly refine recrystallized grains in the hot rolling coil,which exceeds the critical reduction rate,and the recrystallized grain size in the hot rolling coil almost remains unchanged.When the hot rolling temperature is lower than 810 ℃,there is a critical reduction rate to start recrystallization nucleation.With the decrease of the hot rolling temperature,the critical reduction rate increases gradually.