电渣重熔过程增镁及其对夹杂物的影响

Increase of magnesium during electroslag remelting process and its effect on inclusions

通过设计含镁渣系,并在电渣重熔过程添加脱氧剂,氩气保护气氛下进行电渣重熔实验,研究了电渣重熔过程增镁的可能性。用电感耦合等离子体原子发射光谱分析了钢中的镁含量,用ASPEX扫描电镜分析了电渣锭中镁含量对夹杂物尺寸、类型、形貌等的影响。结果表明,渣中含20wt%MgO以上时,即使自耗电极中不含镁,也能使渣中Mg O向钢液中传递镁。实验室条件下,分别用55wt%CaF2–15wt%Al2O3–10wt%CaO–20wt%MgO, 65wt%CaF2–10wt%Al2O3–25wt%MgO, 51wt%CaF2–8wt%Al2O3–8wt%CaO–23wt%MgO–10wt%MgF2渣系重熔时,电渣锭中镁含量分别为0.003 4wt%, 0.003 9wt%, 0.004 3wt%。随电渣锭中镁含量增加,夹杂物组成逐渐从以Al–Ca, Al–Mn–S, Al–Mg–Mn–S为主,转变为以含镁夹杂物为主,镁含量最高达98wt%;夹杂物数量大幅减少,直径明显减小,最大直径均小于10μm,大多数小于5μm。与含镁0.0003wt%的电渣锭相比,镁含量增至0.0034wt%时,夹杂物从357个降至31个,最大夹杂物直径由11.0μm降至8.5μm,平均直径由3.7μm降至3.2μm。

The experiment of electroslag remelting(ESR)was carried out under argon atmosphere by designing magnesium-containing slag system and adding strong deoxidizer to the slag pool continuously,and the possibility of increasing magnesium to electroslag ingot during ESR process was studied in detail.Magnesium content in electroslag ingot was analyzed by inductively coupled plasma atomic emission spectrometry(ICP-AES)and the effect of different magnesium content on the size,type and morphology of inclusions in electroslag ingots were analyzed in detail by ASPEX scanning electron microscopy.The research results showed that when the slag contains more than 20 wt%MgO,even if the metal consumable electrode did not contain Mg,the MgO in slag pool still transferred Mg to the molten steel due to the strong reduction condition of deoxidizer.Under laboratory conditions,the Mg content in the slag ingot reached 0.0034wt%,0.0039wt%and 0.0043wt%respectively when 55wt%CaF2–15wt%Al2O3–10wt%CaO–20wt%MgO slag,65wt%CaF2–10wt%Al2O3–25wt%Mg Oslag and 51 wt%CaF2–8wt%Al2O3–8wt%CaO–23wt%MgO–10wt%MgF2 slag were used for electroslag remelting.With the increase of Mg content in ESR ingots,the composition of inclusions in the electroslag ingot gradually changed from Al–Ca,Al–Mn–S,Al–Mg–Mn–S to Mg-containing inclusions,and the maximum content of Mg in inclusions was 98 wt%.The number of inclusions decreased greatly,and the diameter of inclusions was smaller with the increase of Mg in the electroslag ingot.Especially,the maximum diameter of inclusions in electroslag ingots treated with Mg was less than 10μm,and most of them were less than 5μm.Compared with the electroslag ingot containing 0.0003 wt%Mg,when the Mg content in the electroslag ingot increased to 0.0034 wt%,the number of inclusions decreased from 357 to 31 pcs.The maximum diameter of inclusions decreased from 11.0 to 8.5μm,and the average diameter decreased from 3.7 to 3.2μm.