GH4169合金凝固重熔过程的缺陷特征研究

Investigations on Macroscopic Defects of GH4169 Alloy During the Solidification Process

通过凝固重熔实验和均匀化实验,分析冷却速度、断电时间等凝固参数对GH4169合金凝固重熔过程宏观缺陷的影响。利用扫描电镜观察了GH4169均匀化前后的组织,并用EDS能谱分析了相的成分。结果表明,随着冷却速度的降低,GH4169合金凝固重熔过程出现缩松缺陷的可能性增大,而180 s以内的断电操作对缩松缺陷的分布没有明显影响。经过第一阶段均匀化处理后,Laves相已基本溶入基体,但缩松附近区域易残留大量细小的白色富Nb相和少量块状Laves相,甚至出现白色偏析条带,而富集在缩松周围的Al元素因热处理过程而氧化和烧损,扩大了宏观缺陷的范围。

In this paper, solidification remelting experiment and homogenization treatment were carried out to analyze the characteristics of macroscopic imperfection with the relevant to cooling rate and interrupt time during the solidification remelting process. Microstructures before and after the homogenization treatment were investigated by Scanning Electron Microscope(SEM) and the composition of phases were analyzed by Energy Dispersive Spectroscopy(EDS). The results demonstrated that the possibility of shrinkage porosity was increased with the decrease of cooling rate and independent of the interrupt time within 180 seconds during solidification remelting process. After first-stage homogenization treatment, Laves Phase were almost melted into the matrix, while there were still some Laves Phase, large quantities of Nb-rich phase or even segregation band around the shrinkage holes. Furthermore, Al element enriched around the shrinkage porosity was melting loss by oxidation, enlarging the range of macroscopic imperfection.