La对FeCrAl合金中非金属夹杂物的影响

Effect of La on non-metallic inclusions in FeCrAl alloy

为研究稀土La对FeCrAl合金中夹杂物类型及分布的影响,在热力学分析的基础上,借助SEM-EDS观察分析了夹杂物三维形貌及其成分,统计分析了夹杂物尺寸及数量。结果表明,1 600℃时FeCrAl合金中只存在单一Al_(2)O_(3)夹杂。凝固过程中,随着体系中固相率的增大,AlN在凝固前沿析出。加入质量分数为0.009 3%的La后,Al_(2)O_(3)被变质为LaAlO_(3)。La添加量为0.037 8%时,主要夹杂物类型为LaAlO_(3)+La_(2)O_(2)S,夹杂物数量明显增多,且随着保温时长的增加,La_(2)O_(2)S比例逐渐增加。La添加量为0.096 4%时,La_(2)O_(2)S比例进一步增加,保温60 min后,钢中只有单一La_(2)O_(2)S夹杂稳定存在。夹杂物聚合特性对夹杂物粒径影响显著。1 600℃下保温60 min,仅含单一LaAlO_(3)的试样中,LaAlO_(3)在保温前期呈现较强的聚合趋势,夹杂物平均粒径先由2.34μm增大至3.31μm,随后减小至1.93μm。La_(2)O_(2)S聚合趋势较弱,含有La_(2)O_(2)S的试样中,夹杂物平均粒径较小且变化稳定,在保温前期,夹杂物平均粒径稳定在1.8~2.0μm。

In order to study the influence of rare earth La addition on the type and distribution of inclusions in FeCrAl alloys,based on thermodynamic analysis,the three-dimensional morphology and composition of inclusions were observed and analyzed by SEM-EDS,and the size and quantity of inclusions were statistically analyzed.The results show that single Al_(2)O_(3) only inclusion exists in FeCrAl alloy at 1600℃.During the solidification process,with the increase of the solid fraction in the system,AlN precipitates at the solidification front.After adding 0.0093%La,Al_(2)O_(3) transforms into LaAlO_(3).When the addition amount of La is 0.0378%,the type of inclusions is LaAlO_(3)+La_(2)O_(2)S,and the number of inclusions increases significantly.As holding time prolongs,the proportion of La_(2)O_(2)S gradually increases.When the addition amount of La is 0.0964%,the proportion of La_(2)O_(2)S is further increased.After 60 min of heat preservation,single La_(2)O_(2)S only inclusion exists stably in the steel.The particle size of the inclusions is significantly affected by the aggregation properties of the inclusions.In the samples containing single LaAlO_(3) only at 1600℃for 60 min,LaAlO_(3) shows a strong tendency to aggregate in the early stage of the incubation,and average particle size of the inclusions firstly increases from 2.34μm to 3.31μm,and then decreases to 1.93μm.The tendency of La_(2)O_(2)S to aggregate is weak.In the samples containing La_(2)O_(2)S,average particle size of inclusions is small and uniform,in the early stage of heat preservation,average particle size of inclusions remains in the range of 1.8−2.0μm.