高端抗硫管线钢非金属夹杂物研究

采用扫描电镜和大样电解等检验方法对抗硫管线钢的冶炼过程试样和连铸坯中夹杂物的数量、尺寸、成分、形貌进行系统分析。结果表明:钢液经过LF精炼后,显微夹杂物的面积比降低了34.7%;中间包钢液的夹杂物面积比较VD出站增加了6.1%。LF进站钢液中的夹杂物主要为Al_2O_3夹杂物,在LF精炼和VD真空处理过程中由于钢渣间的相互作用,形成以CaO、MgO、Al_2O_3为主要组成的复合型夹杂物。钙处理后夹杂物中的CaO和Al_2O_3的物质的量比接近12∶7,并与钢液发生了脱硫反应,形成了含CaS的复合夹杂物。中间包开浇阶段铸坯中的显微夹杂物和大型夹杂物都明显高于稳定浇铸状态;在稳定浇铸状态下,铸坯中的w(T[O])小于15×10~(-6),大型夹杂物的含量小于0.2 mg/kg;大型夹杂物的主要来源是钢包引流砂、结晶器保护渣。

Study on Non-metallic Inclusions of Sour Service Pipeline Steel

The number,size,chemical composition and morphology of inclusions in the sour service pipeline steel samples taken from individual steelmaking process stages and billet were analyzed using SEM and bulk sample electrolysis.The results indicate the area fraction of micro inclusions in the liquid steel decreases by 34.7％ in the LF process;the area fraction of micro inclusions in the liquid steel of tundish increases by 6.1％ compared with VD end.The dominant inclusion type is Al2O3 at LF start;The composite inclusions containing mainly CaO、MgO、Al2O3 form due to the steel/slag reaction in the LF and VD process.The amount-of-substance ratio of CaO to Al2O3 in the inclusions is close to 12:7 after calcium treatment,desulphurization reaction between inclusions and liquid steel occurs and forms composite inclusions containing CaS.There are much more micro and macro inclusions in the billet at casting start stage compared with stable casting stage;T[O] content in the billet is less than 15×10-6,and the macro inclusion content in the billet is less than 0.2 mg/kg in the stable casting stage;the macro inclusions in the billet are mainly from filler sand of ladle,mold powder.