摘要：
With high-strength steels with different Ti contents (0.032%~0.153%)as the research ob-jects,the morphology,composition,amount and size distribution of oxide and nitride inclusions were characterized by SEM and EDS.The precipitation behaviors of TiN inclusions were investigated by thermodynamics and kinetics calculation.The results show that when Ti content equals 0.032%,the MgAl2 O4-rich polygonal solid-state inclusions with high melting point will be precipitated during the smelting process ,which may cause the nozzle clogging problem .When Ti content is larger than 0.106%,the spherical liquid-state inclusions rich in TiAl2 O5 will be formed,which can be removed by flotation,and the nozzle clogging phenomenon can be therefore improved.Moreover,through Ca treatment,inclusions rich in MgAl2 O4 can be modified to calcium aluminate with low melting point;meanwhile,the Ti in inclusions can be reduced as well,which will improve the yield of Ti.The aver-age sizes of inclusions and nitrides in Ti-containing high strength steel is around 1~2 and 1~3μm, respectively,which will slightly increase with increase of Ti content.When Ti content is less than 0.04%,the TiN precipitation size could be reduced effectively as the N content in steel is controlled below 0.0018%.When Ti content exceeds 0.1%,it is difficult to prevent the liquidation of TiN in the actual industrial production,but the TiN size can be refined by increasing the amount of fine ox-ides in the steel.%以不同钛含量(0.032%~0.153%)的高强钢为研究对象,利用SEM、EDS等对钢中氧化物及氮化物夹杂的形貌、组成、数量及尺寸分布进行表征,结合热力学与动力学计算,对TiN的析出行为进行分析.结果表明,当钢中Ti含量较低(0.032%)时,冶炼过程会形成富含MgAl2 O4的多边形高熔点固态夹杂,易造成水口堵塞;当Ti含量大于0.106%时,钢中形成了富含TiAl2 O5的液态球形夹杂,可通过上浮去除,不易堵塞水口;Ca处理能将低钛钢中的夹杂改性为低熔点的铝酸钙,不仅降低了水口堵塞风险,还能还原夹杂物中的Ti,提高Ti的收得率.含钛高强钢中夹杂物平均尺寸为1~2μm,氮化物平均尺寸为1~3μm,其均随着Ti含量的增加而稍有增加.当Ti含量小于0.04%时,将钢中N含量控制在0.0018%以下,能有效减小TiN的析出尺寸;当Ti含量大于0.1%时,实际工业生产中很难阻止TiN的液析,但可通过提高钢中细小氧化物的数量,来细化TiN的尺寸.
