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铸坯出结晶器后的冷却速度是影响和决定铸坯表层组织结构(0～5 mm)及第2相析出物分布的关键因素.在开发重熔凝固冷却实验装置的基础上,模拟铸坯在垂直段的凝固冷却条件,研究不同冷却速度对铸坯表层组织与第2相析出物分布的影响.研究表明,在0.8 m.min-1拉速下,以5℃.s-1的冷却速度,使铸坯在出结晶器后表面温度下降到A3温度以下,得到的表层组织均匀,晶界无膜状先共析铁素体,微合金元素析出物在晶内分布均匀,有利于提高铸坯热塑性及降低裂纹敏感性.
The cooling rate after the slab out of the mold is the key factor that affects and determines the distribution of the microstructure (0 ~ 5 mm) and the precipitates in the second phase.Based on the development of remelting and solidification cooling experimental device, In the vertical section of the solidification cooling conditions, the study of different cooling rates on the slab microstructure and the distribution of second phase precipitates.Studies showed that at 0.8 m.min-1 pulling speed, with 5 ℃ .s-1 cooling Speed, so that the slab in the mold after the surface temperature dropped to A3 temperature below the surface of the organization obtained uniform, the grain boundary without pro-eutectoid ferrite, micro-alloying elements precipitates in the crystal distribution is conducive to improving Billet thermoplastic and reduce crack sensitivity.