【作者】 李璟宇； 成国光； 阮强； 潘吉祥； 陈兴润；

【Author】 Jingyu Li;Guoguang Cheng;Qiang Ruan;Jixiang Pan;Xingrun Chen;State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing;Jiuquan Iron and Steel Co.;

【机构】 北京科技大学钢铁冶金新技术国家重点实验室； 酒泉钢铁集团；

【摘要】 针对409L超纯铁素体不锈钢连铸过程中常出现的水口堵塞问题与最终冷轧板表面缺陷问题,通过对精炼过程进行系统取样、分析试样中夹杂物的演变特点,结合热力学计算,研究了409L不锈钢中夹杂物的形成机理,据此提出了合理的工艺改进。LF精炼过程中夹杂物演变特点:铝脱氧后钢中以不规则形状的Al2O3-MgO夹杂物为主;喂入钛线后,钢中主要为不规则形状的Al2O3-MgO-TiOx夹杂物和较大尺寸的复合型CaO-TiOx-Al2O3-MgO夹杂物;LF出站试样中夹杂物类型与喂入钛线后基本相同。热力学计算了Al-Mg-O平衡相图,表明铝脱氧后试样成分位于Al2O3-MgO优势区,与试验结果较为吻合。计算钙处理后Al-Mg-O平衡相图发现钙的添加可以有效减小Al2O3-MgO优势区,形成液态氧化物优势区,有利于氧化物夹杂的去除,提高钢水洁净度。通过计算Al-Ti-O平衡相图,得到了钢中合理铝钛含量范围,以减少有害夹杂物的形成并提高钛合金的收得率:0.0532Ti+0.0033≤Al≤0.1175Ti+0.0046 (0.1≤Ti≤0.44)0.0957Ti-0.0157≤Al≤0.1175Ti+0.0046 (0.44<Ti≤1)结合上述精炼过程中夹杂物形成机理,对现场工艺进行优化改进后,实现了409L超纯铁素体不锈钢四炉连浇,稳定控制冷轧不锈钢产品降级率在2%以下。更多还原

【Abstract】 In response to the clogging of submerged entry nozzle(SEN) and surface defects of cold-rolled 409 L ultra purity ferritic stainless steel, the evolution mechanism of oxide inclusions in 409 L ultra purity ferritic stainless steel during refining process was investigated by industrial experiment and thermodynamic calculation.After the addition of Al, the main type of inclusions in molten steel was irregular MgO-Al2O3 spinel. After titanium addition, two types of inclusions were formed: irregular Al2O3-MgO-TiOx inclusions and spherical complex CaO-TiOx-Al2O3-MgO inclusions. According to the phase diagram of Al-Mg-O, the compositions of steel samples after Al addition were located in Al2O3-MgO phase, which was consistent with the experimental results. Calcium treatment could effectively reduce the distribution of spinel phase and form liquid oxides phase,which facilitated the removal of oxide inclusions and improved the cleanliness of molten steel. The reasonable Al contents and Ti contents in 409 L stainless were determined by the thermodynamic calculation of phase diagram of Al-Ti-O, which could decrease the formation of oxide inclusions and improve titanium yield:0.0532 Ti+0.0033≤Al≤0.1175 Ti+0.0046(0.1 ≤Ti≤0.44)0.0957 Ti-0.0157≤Al≤0.1175 Ti+0.0046( 0.44<Ti≤1)According to the formation mechanism of inclusions during refining process, the refining process has been optimized. Four heats of 409 L ultra purity ferritic stainless steel can be cast continuously. And the surface defects rate of cold-rolled stainless steel has been controlled below 2%.更多还原