鈷基高溫合金GH5605鑄態組織及高溫擴散退火過程中元素再分配

劉超; 江河; 董建新; 章清泉

doi:10.13374/j.issn2095-9389.2019.03.009

鈷基高溫合金GH5605鑄態組織及高溫擴散退火過程中元素再分配

doi: 10.13374/j.issn2095-9389.2019.03.009

劉超¹,
江河^1, ,,
董建新¹,
章清泉²

1.
北京科技大學材料科學與工程學院，北京 100083
2.
北京首鋼冶金研究院，北京 100192

基金項目:

國家自然科學基金資助項目 51571012

中央高校基本業務費資助項目 2017YFB0305201

詳細信息

通訊作者:
江河, E-mail: jianghe17@sina.cn

中圖分類號: TG146.1
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- 文章訪問數: 1268
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- 被引次數: 0
出版歷程
- 收稿日期: 2018-02-03
- 刊出日期: 2019-03-20

As-cast microstructure and redistribution of elements in high-temperature diffusion annealing in cobalt-base superalloy GH5605

1.
School of Materials Science and Technology, University of Science and Technology Beijing, Beijing 100083, China
2.
Beijing Beiye Functional Materials Corporation, Beijing 100192, China

More Information

Corresponding author: JIANG He, E-mail: jinghe17@sina.cn

摘要

摘要: 利用光學顯微鏡(OM)、場發射掃描電子顯微鏡(FESEM)、能譜分析(EDS) 并結合熱力學及動力學計算結果對采用真空感應熔煉和電渣重熔二聯工藝生產的GH5605合金電渣錠的枝晶形貌、元素偏析和析出相進行分析.探索了合金的高溫擴散退火制度并結合差示掃描量熱儀(DSC) 和熱壓縮模擬實驗分析高溫擴散退火前后的合金特征.結果表明: GH5605合金中的枝晶和元素偏析情況較輕, 主要偏析元素是Cr和W并在枝晶間處偏聚, 電渣錠中的主要析出相包括奧氏體、晶界M₂₃C₆以及晶內和晶界處的奧氏體與M₂₃C₆板條狀共晶相.經1210℃/8 h擴散退火處理后枝晶和元素偏析基本消除, 共晶相基本回溶.
- 鈷基高溫合金 /
- 偏析 /
- 枝晶 /
- 共晶 /
- 高溫擴散退火
Abstract: The dendritic morphology, elements segregation index, precipitates morphology, and precipitates types in GH5605 ingot produced by vacuum induction melting and electroslag remelting were investigated by using optical microscopy (OM), field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS) spectrum analysis and the results of thermodynamic and kinetic calculations by Thermal-Calc and JMatPro sofeware. To study the effects of high-temperature diffusion annealing on GH5605 ingot, the annealing system was investigated and the microstructure and macrostructure characteristics of GH5605 ingot were analyzed before and after the diffusion annealing by differential scanning calorimetry (DSC) and thermal compression simulation tests in Gleeble 3800 test machine. In the OM results, dendrites are not obvious, and secondary dendritic arms cannot be distinguished in the GH5605 surface but they are gradually clearer toward the center area. The EDS results show that element segregation index is comparably small in GH5605 ingot; every element segregation index is in the range of 0. 9-1. 4 which is not as large as those of nickelbased superalloy. The main segregating elements during solidification are Cr and W which mainly segregate in the dendritic regions.According to the FESEM results, the precipitate phases include austenite and grain boundary carbide M₂₃C₆ and because of the Cr and W segregation at dendritic arms, an unexpected eutectic phase comprising austenite and M₂₃C₆ appears, and the alternating lamellae of austentite and M₂₃C₆ develop a lathlike morphology. Different macrostructure and microstructure characteristics including the morphology of dendritic, elements segregation index, grain size, morphology and the amount of eutectic phase were analyzed and compared in different annealing times. The high-temperature diffusion annealing system is optimal at 1210 ℃/8 h, at which the dendrites and elemental segregation are substantially eliminated, and the eutectic phase is almost dissolved.
- cobalt-base superalloy /
- segregation /
- dendritic /
- eutectic /
- high temperature diffusion annealing

HTML全文

圖 1 電渣錠低倍形貌(a) 及不同位置金相組織和背散射照片. (b, e) 外緣; (c, f) 1/2半徑; (d, g) 心部

Figure 1. Low magnitude morphology (a) and metallography and backscatter photos of electroslag ingot at different positions: (b, e) edge; (c, f) 1/2radius; (d, g) center

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圖 2 Cr (a) 和W (b) 凝固過程再分配規律

Figure 2. Redistribution rules of Cr (a) and W (b) during solidification

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圖 3 電渣錠組織(a) 及局部放大圖(b)

Figure 3. Microstructure (a) and local magnitude micrographs (b) of ingot

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圖 4 電渣錠晶內(a, b) 和晶界(c, d) 典型析出相形貌

Figure 4. Typical precipitates morphology of inner grain (a, b) and grain boundary (c, d) in ingot

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圖 5 晶界典型形貌

Figure 5. Typical grain boundary morphology

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圖 6 GH5605合金平衡相圖(a) 和凝固動力學曲線(b)

Figure 6. Equilibrium phase diagram (a) and the solidification kinetics curve (b) of GH5605

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圖 7 GH5605合金電渣錠差示掃描量熱曲線

Figure 7. DSC curve of GH5605 ingot

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圖 8 1210℃保溫不同時間后電渣錠心部金相照片. (a) 4 h; (b) 8 h; (c) 12 h

Figure 8. Metallography of ingot center after annealing at 1210℃for different time: (a) 4 h; (b) 8 h; (c) 12 h

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圖 9 高溫擴散退火后GH5605合金的差示掃描量熱曲線

Figure 9. DSC curve of GH5605 after high temperature diffusion annealing

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圖 10 晶粒尺寸隨退火時間演變規律

Figure 10. Grain size evolution with annealing time

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圖 11 鑄態(a) 和退火態(b) Gleeble試樣顯微組織

Figure 11. Micrographs of as-cast (a) and annealing (b) Gleeble test samples

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表 1 GH5605合金化學成分(質量分數)

Table 1. Main chemical composition of GH5605 superalloy ?%

C	Cr	Mn	Fe	Ni	W	Co
0.09	19.75	1.55	2.40	10.36	14.65	余量

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表 2 GH5605合金枝晶間距

Table 2. Dendrite spacing in GH5605 superalloy

取樣位置	一次枝晶間距/μm	二次枝晶間距/μm
外緣	115.65	93.25
1/2半徑	225.00	115.00
心部	237.50	132.13

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表 3 鑄錠元素偏析系數

Table 3. Elements segregation coefficient of ingot

取樣位置	C	Cr	Mn	Fe	Co	Ni	W
外緣	0.97	1.10	1.31	0.92	0.93	0.94	1.13
1/2半徑	0.95	1.08	1.31	0.93	0.95	0.96	1.10
心部	0.94	1.14	1.40	0.86	0.91	0.87	1.25
平均值	0.95	1.11	1.34	0.90	0.93	0.92	1.16

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表 4 典型析出相成分(質量分數)

Table 4. Composition of typical precipitates ?%

析出相	C	Cr	Mn	Fe	Co	Ni	W
晶界析出相	4.73	43.99	1.95	1.67	22.68	4.42	20.57
島狀析出相	3.33	26.39	1.46	1.04	18.70	2.24	46.84

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表 5 不同退火制度下Cr和W的元素偏析系數

Table 5. Elements segregation coefficients of Cr and W in different an-nealing system

元素	鑄態	1210℃/4h	1210℃/8h	1210℃/12h
Cr	1.11	1.06	1.00	1.00
W	1.16	1.04	1.00	1.00

下載: 導出CSV

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