电渣重熔对FeCrAl不锈钢中夹杂物的影响

应用扫描电镜(SEM)及X射线能谱分析仪(EDS)对真空感应炉熔炼(VIM)和电渣重熔炉熔炼(ESR)的FeCrAl不锈钢中夹杂物的成分、形貌、数量、大小进行统计分析。结果表明,AlN是2个钢锭的主要夹杂物,电渣重熔过程中产生的高熔点稀土化合物可作为AlN析出的异质核心。电渣重熔使自耗电极中尺寸大于10μm的夹杂物基本消失,ESR锭中尺寸小于5μm的夹杂物达到86.7%。电渣重熔减小了AlN的平均尺寸,去除了大尺寸的AlN,使AlN的总面积明显减小。热力学计算结果表明,VIM锭中AlN可以直接在液相中析出;ESR锭中氮含量的降低造成AlN不能直接在液相中析出,随着凝固的进行,Al]和N]在残余液相中富集,当凝固分率大于0.615后,AlN才能在凝固前沿的残余液相中析出。

Effect of electroslag remelting on inclusions in FeCrAl stainless steel

The characteristics of inclusions in FeCrAl stainless steel produced by vacuum induction melting(VIM) and electroslag remelting(ESR) were investigated by scanning electron microscopy (SEM) and X- ray energy- dispersive spectrometry (EDS). The composition, morphology, number and dimension of inclusions were analyzed in the ingots of VIM and ESR respectively. The result shows that AlN is the dominating inclusion in the two ingots, ESR produces some kinds of rare earth compounds with high melting point as the heterogeneous nuclei to promote the precipitate of AlN. The inclusions of size larger than 10??m in consumable electrode disappeared after remelting, while the inclusions in ESR ingot smaller than 5??m took 86.7% of the total inclusions. ESR reduced the average size of the AlN and removed the large size of AlN, then reduced the total area of the AlN significantly. The results of thermodynamic calculations show that AlN inclusions are able to precipitate in the liquid metal pool during VIM directly, while it is different during ESR because of the low content of N. With the enrichment of N and Al at the solidifying front, the precipitation of AlN inclusions could take place when solidification fraction is larger than 0.615.