Q345钢液凝固及铸坯冷却过程中非金属夹杂物的组成演变

炼钢

Q345钢液凝固及铸坯冷却过程中非金属夹杂物的组成演变

王祎，张立峰2，杨文1，雷勋惠1，张继1，赵根安1

（1.北京科技大学冶金与生态工程学院，北京100083； 2.燕山大学亚稳态材料制备技术与科学国家重点实验室，河北秦皇岛066004）

接受日期:1900-01-01 出版日期:2020-04-05

Evolution of non-metallic inclusion composition during cooling and solidification process of Q345 steel

Accepted:1900-01-01 Online:2020-04-05

摘要/Abstract

摘要： Q345钢生产过程中通过钙处理改性夹杂物，中间包钢水中夹杂物为钙铝酸盐包裹镁铝尖晶石的结构，平均成分为45.71 %Al2O3-40.22 %CaO-6.50 %MgO-6.60 %CaS-0.97 %SiO2。连铸坯冷却凝固过程，夹杂物发生转变，连铸坯表层冷却速度快，相转变来不及发生，夹杂物成分与中间包钢水中相差不大。连铸坯内弧1/4处夹杂物转变为CaS和MnS包裹镁铝尖晶石的结构，忽略MnS归一化后的平均成分为56.00 %Al2O3-9.28 %CaO-9.07 %MgO-25.06 %CaS-0.58 %SiO2。从连铸坯边部到中心，夹杂物Al2O3和CaS含量显著升高，CaO含量显著降低，夹杂物中硫化物面积分数从边部的0.000 01 %升高至中心的0.002 9 %，表明硫化物在连铸坯冷却凝固过程中大量析出。采用Factsage 7.0热力学软件计算了Q345钢冷却凝固过程夹杂物的转变，结果与夹杂物检测结果变化趋势一致，且小尺寸夹杂物因动力学上转变更充分而与计算结果更接近。

关键词: Q345钢, 夹杂物, 冷却凝固, 析出

Abstract: Inclusions in Q345 steel were modified by calcium treatment. Inclusions in tundish molten steel were MgO•Al2O3 spinel with CaO-Al2O3 wrapped outside. The average composition of inclusions in molten steel was 45.71%Al2O3-40.22%CaO-6.50%MgO-6.60%CaS-0.97%SiO2. Transformation of inclusions occurred during solidification of slab. Near the surface of the slab, phase transformation of inclusions did not have enough time. Therefore, the composition of inclusions was almost the same as in molten steel. At the 1/4 of slab width from the loose side, the inclusions were MgO•Al2O3 spinel with CaS-MnS wrapped outside. The average composition of inclusions was 56.00%Al2O3-9.28%CaO-9.07%MgO-25.06%CaS-0.58%SiO2 while MnS was neglected. From surface to center of slab, the Al2O3 and CaS content of inclusions increased, CaO content decreased, while area fraction of sulfides increased from 0.000 01 %to 0.002 9 %, indicating the precipitation of sulfides. Transformation of inclusions in Q345 steel during cooling and solidification process was calculated using Factsage 7.0. The results were of good consistence to the detected ones, especially for inclusions with smaller size.

Key words: Q345 steel, inclusion, solidification, precipitation

王祎,张立峰2，杨文1，雷勋惠1，张继1，赵根安1. Q345钢液凝固及铸坯冷却过程中非金属夹杂物的组成演变[J]. 炼钢.

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