EAF-LF/VD-CC流程生产高压锅炉钢的工艺

Process of high-pressure boiler steel produced by EAF-LF/VD-CC

天津钢管集团有限公司炼钢厂采用EAF全程泡沫渣埋弧操作、EBT出钢合金化、LF复合精炼渣精炼、VD处理后喂硅钙线、连铸全程保护浇铸生产高压锅炉钢12Cr1MoVG.通过系统取样、示踪剂追踪、综合分析等方法,对LF处理前后、中间包钢水和连铸坯中总氧(T[O])、显微夹杂及大型夹杂物的数量及变化情况进行了全面研究.结果表明,LF/VD精炼后钢液T[O]平均为15×10-6,中间包T[O]为17×10-6,铸坯为18×10-6～24×10-6;铸坯中的显微夹杂物数量是3.53mm-2,主要为球形钙铝酸盐、硅铝酸盐和铝酸盐与硫化物的复合夹杂,90%以上的夹杂物尺寸小于10μm;铸坯中大型夹杂物有铁铝硅酸盐、钙镁硅酸盐等.低倍组织均匀细致,表面质量良好,轧管各项技术指标均达到GB5310要求.

The high-pressure boiler steel 12Cr1MoVG was produced in steelmaking plant,TPCO,by using foaming slag submerged arc operation in the whole period of EAF steelmaking,EBT tapping alloying,LF compound refining slag,Ca-Si wire feeding after VD treatment and casting with shielding practice.The quantity and changes of total oxygen,microinclusions and macroinclusions in the liquid steel in different steps were stud-ied by the way of sampling systematically,tracers and comprehensive analyses.The results show that the T[O] is 15×10?6 after LF/VD refining and 17×10?6 in tundish,and the T[O] of cast billets was 18×10-6~24×10?6.The number of microinclusions was 3.53 mm?2 with sizes less than 10 μm,which were mainly spherical calcium alu-minate,aluminosilicate and compound inclusions of aluminate and sulphide.The macroinclusions were mainly ferrum-aluminum silicate,magnesium-calcium silicate,etc.The macrostructure is uniform and the surface quality is good.Each technical index meets the requirement of GB5310 standard.