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利用电渣重熔连续定向凝固技术(ESR-CDS)成功制备了Rene88DT高温合金铸锭。借助于金相显微镜,带有能谱的扫描电镜以及透射电镜,对电渣重熔连续定向合金Rene88DT铸锭进行分析,并与传统电渣铸锭进行了对比。研究结果显示,电渣重熔连续定向凝固合金Rene88DT铸锭消除了最为严重的中心偏析,中心偏析在传统电渣铸锭中是普遍存在的,这种偏析存在于柱状晶与等轴晶交界处或者柱状晶之间相互交界面处。此外,电渣重熔连续定向凝固合金二次枝晶间距较传统电渣铸锭小,析出相尺寸也较小。由于微观偏析程度的降低,使得合金在经过1200℃,24 h后的热处理即可达到均匀化效果。夹杂物统计结果显示,电渣重熔连续定向凝固合金夹杂物最大尺寸为5.89μm,与传统电渣合金和粉末合金相比夹杂物数量降低60%。电渣重熔连续定向凝固合金宏观偏析和夹杂物水平的降低可提高热加工塑性,为铸和锻工艺实施提供基础。
Rene88DT superalloy ingot was successfully prepared by electroslag remelting continuous directional solidification (ESR-CDS). The electroslag remelted continuously oriented alloy Rene88DT ingot was analyzed by metallographic microscope, SEM with energy spectrum and transmission electron microscope, and compared with the traditional electroslag ingot. The results show that ESR Rene88DT ingot eliminates the most serious center segregation, which is common in traditional electroslag ingot ingot. This segregation exists at the junction of columnar and equiaxed grains Or between the columnar crystals at the interface. In addition, the secondary dendrite spacing of electroslag remelting continuous directional solidification alloy is smaller than the traditional electroslag ingot, the size of precipitated phase is also smaller. As the degree of micro-segregation decreases, the homogenization effect can be achieved by the heat treatment of the alloy at 1200 ℃ for 24 h. The statistical results of inclusions show that the maximum size of the ESR inclusions is 5.89μm, and the number of inclusions is reduced by 60% compared with the traditional ESR and powder alloys. The macrosegregation of inclusions and the reduction of inclusions in electroslag remelting continuous oriented solidified alloys can improve the hot workability and provide the foundation for the implementation of casting and forging process.