Evolution mechanism of inclusions in GH4169 produced by vacuum induction melting
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摘要: 高温合金中夹杂物是影响合金冶金质量和使用性能的主要因素,因此研究了GH4169镍基高温合金真空感应(VIM)熔炼制备过程中夹杂物的演变机制。采用真空感应炉对GH4169合金进行冶炼,通过ASPEX型自动扫描电镜分析检测夹杂物的物相组成、尺寸形貌及成分,并分析夹杂物的形成机理、来源及演变机制。结果表明,真空熔炼GH4169合金主要生成五种类型夹杂物:Al2O3、MgAl2O4和MgO单层夹杂物,MgAl2O4-Ti(C,N)-NbC和MgO-Ti(C,N)-NbC多层复合夹杂物。Al2O3在熔化期形成,MgAl2O4在精炼期形成,加入Nb、Al、Ti合金化后形成MgAl2O4-Ti(C,N)-NbC夹杂,加入Mg合金化后生成MgO和MgO-Ti(C,N)-NbC夹杂。随冶炼过程的进行,夹杂物的数量密度先增加后减少,在精炼期夹杂物数量密度达到峰值211.42个/mm2,精炼期结束后,夹杂物数量减少,出钢前夹杂物数量密度46.57个/mm2。Abstract: Inclusion had been considered as main factor affecting metallurgical quality and mechanical property of Ni-based superalloys. In this work the evolution mechanism of inclusions during the preparation of GH4169 Ni-based superalloy by vacuum induction melting (VIM) was studied. A method of ASPEX automatic scanning electron microscope was utilized to characterize the inclusions in GH4169 Ni-based superalloy prepared by vacuum induction melting (VIM). The phases, compositions, morphologies, formation mechanism and evolution mechanism of the inclusions were analyzed. The results indicate that the inclusions of single phase in GH4169 include mainly Al2O3、MgAl2O4 and MgO. The inclusions of composite phases include mainly MgAl2O4-Ti(C,N)-NbC and MgO-Ti(C,N)-NbC. Al2O3 forms during melting period, MgAl2O4 forms during refining period, and MgAl2O4-Ti(C,N)-NbC forms after alloying with Nb, Al and Ti, and MgO and MgO-Ti(C,N)-NbC form after alloying with Mg. As smelting process going, the number density of inclusions firstly increases and then decreases, and the number density of inclusions reaches a peak value of 211.42/mm2 during the refining period. After the refining period, the number of inclusions decreases, and the number density of inclusions before pouring is 46.57/mm2.
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Key words:
- GH4169 alloy /
- vacuum induction melting /
- inclusions /
- evolution mechanism
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表 1 GH4169高温合金的化学成分
Table 1. Chemical composition of GH4169 superalloy
% Ni Cr Mo Nb Al Ti Mg C Fe 50.0~55.0 17.0~20.0 2.8~3.2 5.0~5.5 0.5~0.7 0.8~1.5 ≤0.05 ≤0.08 余量 -
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