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摘要: 為控制Incoloy825合金中的Al、Ti含量,并減少電渣過程中氟化物的揮發。借助FactSage熱力學軟件,建立渣?金反應的熱力學模型。設計出適宜控制Al、Ti含量的低氟渣系,探究了渣中組元與Al2O3和TiO2活度比的關系,并通過高溫渣–金平衡實驗進行驗證。結果表明:當渣中CaO和Al2O3含量增加,導致
$\lg \left( {{{a_{{\rm{A}}{{\rm{l}}_{\rm{2}}}{{\rm{O}}_{\rm{3}}}}^2} / {a_{{\rm{Ti}}{{\rm{O}}_{\rm{2}}}}^3}}} \right)$ 值升高,即合金中Ti含量降低,Al含量升高;與此相反,渣中TiO2含量升高,使$\lg \left( {{{a_{{\rm{A}}{{\rm{l}}_{\rm{2}}}{{\rm{O}}_{\rm{3}}}}^2} / {a_{{\rm{Ti}}{{\rm{O}}_{\rm{2}}}}^3}}} \right)$ 值降低,即Ti含量增加,Al含量減少;渣中CaF2和MgO含量的增加對$\lg \left( {{{a_{{\rm{A}}{{\rm{l}}_{\rm{2}}}{{\rm{O}}_{\rm{3}}}}^2} / {a_{{\rm{Ti}}{{\rm{O}}_{\rm{2}}}}^3}}} \right)$ 的影響較小。合金中Al、Ti含量相差較大時,合金中Ti元素易氧化;Al、Ti含量相差較小時,Al元素易氧化。渣中CaO的質量分數為30%~33%、Al2O3的質量分數為30%~33%、TiO2的質量分數為6%~12%、CaF2的質量分數為20%~30%、MgO的質量分數為1%~5%時,能夠有效控制合金中Al、Ti元素含量。-
關鍵詞:
- 熱力學 /
- 電渣重熔 /
- Incoloy825合金 /
- FactSage /
- 活度比
Abstract: Incoloy825 alloy is extensively used in the aerospace and petrochemical industries owing to its excellent corrosion resistance and mechanical properties. It is a solid solution-strengthened Fe?Cr?Ni-based corrosion-resistant alloy. The changes in the Al and Ti contents of the alloy determine the precipitation temperature of the strengthening phases γ '(Ni3AlTi) and Ti (C, N) in the alloy. At present, the main production methods of Incoloy825 alloy are vacuum melting and electroslag remelting. However, owing to the reaction of the components in the slag with the Al and Ti elements in the alloy during the electroslag remelting process, the axial component distribution of the Al and Ti elements in the electroslag ingot is not homogeneous, which seriously affects the quality of the electroslag ingot. It is necessary to control the Al and Ti contents in Incoloy825 alloy and reduce the volatilization of fluoride during the electroslag remelting process. The thermodynamic model of slag metal reaction was established using FactSage thermodynamic software. A low-fluorine slag system suitable for controlling Al and Ti contents was designed, and the relationship between the components in the slag and the activity ratios of Al2O3 and TiO2 was studied, the result was verified by a high-temperature slag metal equilibrium experiment. The results show that the CaO and Al2O3 contents in slag increases with increase in the$\lg \left( {{{a_{{\rm{A}}{{\rm{l}}_{\rm{2}}}{{\rm{O}}_{\rm{3}}}}^2} / {a_{{\rm{Ti}}{{\rm{O}}_{\rm{2}}}}^3}}} \right)$ value, while the Ti content in the alloy decreases with increasing Al content. Moreover, as the TiO2 content in the slag increases, the$\lg \left( {{{a_{{\rm{A}}{{\rm{l}}_{\rm{2}}}{{\rm{O}}_{\rm{3}}}}^2} / {a_{{\rm{Ti}}{{\rm{O}}_{\rm{2}}}}^3}}} \right)$ value decreases, Ti content increases and Al content decreases. The CaF2 and MgO contents in the slag increase have a little effect with the$\lg \left( {{{a_{{\rm{A}}{{\rm{l}}_{\rm{2}}}{{\rm{O}}_{\rm{3}}}}^2} / {a_{{\rm{Ti}}{{\rm{O}}_{\rm{2}}}}^3}}} \right)$ value. When the difference between the Al and Ti contents in the alloy is large, the elemental Ti in the alloy is easy to be oxidized; when difference between the Al and Ti contents is small, the elemental Al is easy to be oxidized. When the mass percent of CaO and Al2O3 in the slag are 30%?33% respectively, the mass percent of TiO2 is 6%?12%, the mass percent of CaF2 is 20%?30%, the mass percent of MgO is 1%?5%, the Al and Ti contents in the alloy can be controlled.-
Key words:
- thermodynamics /
- electroslag remelting /
- Incoloy825 alloy /
- FactSage /
- activity ratio
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圖 1 渣中組元與
$\lg \left( {{{a_{{\rm{A}}{{\rm{l}}_{\rm{2}}}{{\rm{O}}_{\rm{3}}}}^2} / {a_{{\rm{Ti}}{{\rm{O}}_{\rm{2}}}}^3}}} \right)$ 的關系。(a) CaO;(b)Al2O3;(c)TiO2;(d)MgO;(e)CaF2Figure 1. Relationship between component in slag and
$\lg \left( {{{a_{{\rm{A}}{{\rm{l}}_{\rm{2}}}{{\rm{O}}_{\rm{3}}}}^2} / {a_{{\rm{Ti}}{{\rm{O}}_{\rm{2}}}}^3}}} \right)$ : (a) CaO; (b) Al2O3; (c) TiO2; (d) MgO; (e) CaF2表 1 Incoloy825合金中組元的活度相互作用系數[23-24]
Table 1. Activity interaction coefficient of the alloying elements in Incoloy825 alloy
$e_i^j$ Mn Cr Ni Al Ti Cu Mo Al 0.034 0.045 ?0.0376 0.040 Ti ?0.12 0.025 ?0.0166 0.048 0.014 0.016 表 2 Incoloy825合金成分(質量分數)
Table 2. Chemical composition of the Incoloy825 alloy
% C Mn Si P S Cr Mo Ni Cu Al Ti Fe ≤0.025 ≤1.0 ≤0.5 19.5?23.5 2.5?3.5 38?46 1.5?3.0 ≤0.2 0.6?1.2 bal 0.010 0.107 0.131 0.009 0.009 20.620 3.180 38.880 1.660 0.120 1.000 bal. 表 3 渣–金反應前后渣成分
Table 3. Composition of slag before and after slag-metal reaction
% Slag Before reaction After reaction CaF2 CaO Al2O3 MgO TiO2 CaF2 CaO Al2O3 MgO TiO2 S1 25.0 33.0 33.0 3.0 6.0 19.6 37.2 31.4 4.2 7.6 S2 25.0 31.0 31.0 3.0 10.0 19.8 36.3 30.2 4.1 9.5 S3 25.0 30.0 30.0 3.0 12.0 20.1 35.5 29.4 4.2 10.8 www.77susu.com -
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