稀土处理HRB400E钢洁净度研究

Research on cleanliness of HRB400E steel treated with rare earth

为了研究稀土对HRB400E螺纹钢中夹杂物成分和形貌的影响,对稀土处理后螺纹钢中可能存在的夹杂物进行热力学计算,并通过扫描电镜及能谱仪对稀土处理前后HRB400E钢中夹杂物进行了表征和分析。结果表明,稀土可在现场冶炼时加入到螺纹钢中并且质量分数达到0.003 2%;稀土有净化钢液的作用,使钢中S质量分数从0.018%降低到0.004%,降低了77.78%;热力学计算表明,稀土质量分数为0.003 2%时,夹杂物生成的可能性由高到低为REAlO3、RE2O2S、Al2O3。稀土对HRB400E钢中硫、氧化夹杂物有良好的改质效果,将夹杂物变质为RE2O2S和REAlO3,稀土元素与S结合使钢中MnS夹杂的析出减少,有利于钢材综合性能的提升。

In order to study the effect of rare earth(RE)on the composition and morphology of inclusions in HRB400E steel,the possible inclusions in the treated steel were calculated by thermodynamics,and the inclusions in HRB400E steel before and after rare earth treatment were characterized and analyzed by SEM and EDS.The result showed that Rare earth can be added in the smelting process of screw steel and the amount of added rare earth can reach 0.0032%;the rare earth can purify the molten steel and reduce the S content of the steel from 0.018%to 0.004%by 77.78%;When the content of rare earth is 0.0032%,the results of the thermodynamic show that order of the possible inclusion formation in the steel is REAlO3>RE2O2S>Al2O3.The rare earth element plays a certain role in the modification of sulfur and oxygen inclusions.The inclusions are modified into RE2O2S and REAlO3,the combination of rare earth elements and S reduces the precipitation of MnS inclusions in steel,which improves the properties of the steel.