喷淋水量分布对C38N2钢大方坯冷却效果的影响

合理的连铸二冷工艺制度是提高非调质钢连铸坯质量的关键。以某钢厂320 mm×480 mm C38N2非调质钢为研究对象,建立了基于大方坯横向水量分布的凝固传热模型,分析二冷区各段喷淋水量分布对铸坯表面温度分布的影响。研究表明,在现行工艺喷淋条件下,二冷一段和二段铸坯边角部喷淋水量较大,铸坯在二冷一段出口内弧和侧弧的表面横向温差分别达到了340 ℃和327 ℃,三段和四段铸坯表面中心喷淋水量较大,铸坯在空冷区内弧和侧弧的表面回温分别为109 ℃/m和125 ℃/m,容易引发角部裂纹和内部裂纹。在此基础上,提出“在二冷一段和二段降低喷淋高度+三段和四段升高喷淋高度”的喷嘴布置方式。水量分布优化后,二冷各段出口表面横向温差基本控制在200 ℃以内,铸坯在空冷区内弧和侧弧表面回温分别降低至95 ℃/m和107 ℃/m,角部回温由94 ℃/m降低至40 ℃/m,降低了裂纹缺陷发生率。研究结果可为该类非调质钢连铸生产提供借鉴。

Influence of spray water distribution on cooling effect of C38N2 bloom

Reasonable secondary cooling process system of continuous casting is the key to improve the quality of non-quenched and tempered steel bloom. Taking 320 mm × 480 mm C38N2 non-quenched and tempered steel in a steel plant as the research object, a heat transfer and solidification model based on transverse water distribution of bloom was established, to analyze the influence of spray water distribution in each section of secondary cooling zone on the surface temperature distribution of bloom. The results showed that under the current spray conditions, the spray water at bloom corner in the first and second sections of the second cooling zone was large, and the surface transverse temperature differences of inner arc and side arc at the exit of the first section in second cooling zone reached 340 ℃ and 327 ℃, respectively. Meanwhile, the spray water at the bloom surface center in the third and fourth sections of the secondary cooling zone was large, and the surface recovery temperatures of inner arc and side arc in the air cooling zone were 109 ℃/m and 125 ℃/m, respectively, which was easy to cause corner cracks and internal cracks. On this basis, a spray nozzle arrangement mode of "lowering spray height in the first and second sections + increasing spray height in the third and fourth sections of the secondary cooling zone " was proposed. After the optimization of spay water distribution, the transverse temperature difference at the exit surface of each section of the secondary cooling zone was basically controlled within 200 ℃, the surface recovery temperatures of inner arc and side arc in the air cooling zone were reduced to 95 ℃/m and 107 ℃/m, respectively, and the corner recovery temperature was reduced from 94 ℃/m to 40 ℃/m, which reduced the incidence of crack defects. The result of study can provide reference for continuous casting production of non-quenched and tempered steel.