Thermodynamic Nature of SiO2 and FeO in Flux O Potential Control Subject to Submerged Arc Welding Process
Abstract
:1. Introduction
2. Materials and Methods
2.1. Flux Preparation
2.2. Thermodynamic Calculation
- The FToxid database was selected to model the slag.
- The equilibrium temperature of 2000 °C was set.
- The measured slag compositions were set as the input compositions.
- FToxid, Fstel, and FactPS databases are selected. The solution phases of ASlag-liq all oxides, S (FToxid-SLAGA), and LIQUID (FStel-Liqu) were selected to model the molten slag and metal phases.
- The equilibrium temperature of 2000 °C was set.
- The flux formulas and nominal compositions (if the dilution value is not given, it may be assumed to be 0.5) were set as the input chemistries [30].
3. Results and Discussion
3.1. Flux O Potential vs. SiO2 and FeO Activities in Bulk Slag
3.2. Flux O Potential vs. FeO Uptake in Bulk Slag
3.3. Flux O Potential FeO Activity at Slag–Metal Interface
- The molten slag and weld pool are shielded under the flux, making the FeO activity unmeasurable.
- The impact of gas formation on the transfer behaviors in SAW was not considered.
- The measurement in terms of the slag is needed to obtain the FeO uptake level.
4. Conclusions
- For SiO2-enriched acid fluxes, both activities of SiO2 and FeO in the bulk slag may be able to evaluate the flux O potential. For SiO2-enriched acid fluxes with FeO incorporated, the FeO activity in the bulk slag is more feasible than the SiO2 activity to evaluate the flux O potential since the transfer of FeO is less kinetically constrained than that of SiO2.
- For basic fluxes, the level of the FeO uptake in the slag is more suitable for the identification of the O potential in comparison to the FeO activity in the bulk slag since Reaction (4) generally proceeds forward under such circumstances.
- Although the equilibrium FeO activity is unmeasurable, the value can be simulated by the gas–slag–metal equilibrium model. Thermodynamic analysis shows that the simulated equilibrium FeO activity possesses a good generality in the evaluation of the flux potential for both acid and basic fluxes.
- In comparison to the oxide activity (or content) in the slag, no measurement of the slag composition is needed for the calculation of the equilibrium FeO activity, which may pave a vital way to save the experimental resources on the flux’s design and analysis.
Author Contributions
Funding
Conflicts of Interest
References
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Flux | MnO | SiO2 | FeO | BI |
---|---|---|---|---|
F-1-1 | 60 | 40 | 0 | 0.75 |
F-1-2 | 55 | 40 | 5 | 0.75 |
F-1-3 | 50 | 40 | 10 | 0.75 |
F-1-4 | 45 | 40 | 15 | 0.75 |
F-1-5 | 40 | 40 | 20 | 0.75 |
F-1-6 | 35 | 40 | 25 | 0.75 |
F-1-7 | 30 | 40 | 30 | 0.75 |
F-1-8 | 25 | 40 | 35 | 0.75 |
F-1-9 | 20 | 40 | 40 | 0.75 |
F-1-10 | 15 | 40 | 45 | 0.75 |
F-1-11 | 10 | 40 | 50 | 0.75 |
F-1-12 | 5 | 40 | 55 | 0.75 |
F-1-13 | 0 | 40 | 60 | 0.75 |
Flux | Cr2O3 | SiO2 | Na2O | CaF2 | BI |
---|---|---|---|---|---|
F-2-1 | 12.58 | 7.99 | 0.52 | 78.91 | 5.56 |
F-2-2 | 22.89 | 7.56 | 0.48 | 69.07 | 3.66 |
F-2-3 | 32.88 | 7.63 | 0.55 | 58.94 | 2.47 |
F-2-4 | 41.99 | 7.88 | 0.61 | 49.52 | 1.74 |
F-2-5 | 53.19 | 7.66 | 0.49 | 38.66 | 1.14 |
Flux | F-3-1 | F-3-2 | F-3-3 | F-3-4 | F-3-5 |
---|---|---|---|---|---|
MnO | 0.9 | 5.8 | 1.1 | 6.8 | 12.3 |
CaO | 5.8 | 3.7 | 6.7 | 0.1 | 2.3 |
Al2O3 | 13.9 | 17.3 | 17.9 | 24.9 | 36 |
SiO2 | 15.1 | 21.3 | 13.4 | 19.6 | 18.6 |
CaF2 | 25.7 | 22.6 | 25.9 | 17.9 | 4.2 |
MgO | 32.1 | 21.2 | 29.8 | 22.2 | 4.9 |
FeO | 0.6 | 0.9 | 1 | 2.4 | 5.4 |
TiO2 | 0.7 | 1.9 | 1.2 | 1 | 10.7 |
ZrO2 | 0 | 0 | 0 | 0 | 0.2 |
Na2O | 2 | 2.7 | 1.6 | 1.6 | 2.2 |
K2O | 0.8 | 1.5 | 1.2 | 0.2 | 0.5 |
BI | 3 | 1.8 | 2.9 | 1.4 | 0.5 |
Flux | αNSiO2 | αNFeO | O Content in WM (wt pct) |
---|---|---|---|
F-1-1 | 0.438 | 0.037 | 0.069 |
F-1-2 | 0.437 | 0.062 | 0.071 |
F-1-3 | 0.504 | 0.083 | 0.07 |
F-1-4 | 0.468 | 0.114 | 0.071 |
F-1-5 | 0.480 | 0.148 | 0.084 |
F-1-6 | 0.595 | 0.131 | 0.083 |
F-1-7 | 0.625 | 0.137 | 0.09 |
F-1-8 | 0.501 | 0.228 | 0.092 |
F-1-9 | 0.561 | 0.235 | 0.09 |
F-1-10 | 0.668 | 0.210 | 0.085 |
F-1-11 | 0.668 | 0.247 | 0.094 |
F-1-12 | 0.555 | 0.339 | 0.103 |
F-1-13 | 0.528 | 0.395 | 0.118 |
F-2-1 | 0.073 | 0.093 | 0.049 |
F-2-2 | 0.077 | 0.130 | 0.074 |
F-2-3 | 0.076 | 0.167 | 0.118 |
F-2-4 | 0.087 | 0.178 | 0.147 |
F-2-5 | 0.112 | 0.169 | 0.162 |
F-3-1 | 0.040 | 0.034 | 0.04 |
F-3-2 | 0.070 | 0.034 | 0.0377 |
F-3-3 | 0.122 | 0.031 | 0.0437 |
F-3-4 | 0.161 | 0.043 | 0.0499 |
F-3-5 | 0.248 | 0.043 | 0.0687 |
Flux | αFeO | O Content in WM (wt pct) |
---|---|---|
F-1-1 | 0.061 | 0.069 |
F-1-2 | 0.075 | 0.071 |
F-1-3 | 0.093 | 0.07 |
F-1-4 | 0.116 | 0.071 |
F-1-5 | 0.144 | 0.084 |
F-1-6 | 0.175 | 0.083 |
F-1-7 | 0.207 | 0.09 |
F-1-8 | 0.241 | 0.092 |
F-1-9 | 0.276 | 0.09 |
F-1-10 | 0.310 | 0.085 |
F-1-11 | 0.344 | 0.094 |
F-1-12 | 0.376 | 0.103 |
F-1-13 | 0.407 | 0.118 |
F-2-1 | 0.183 | 0.049 |
F-2-2 | 0.232 | 0.074 |
F-2-3 | 0.243 | 0.118 |
F-2-4 | 0.243 | 0.147 |
F-2-5 | 0.239 | 0.162 |
F-3-1 | 0.008 | 0.04 |
F-3-2 | 0.024 | 0.038 |
F-3-3 | 0.009 | 0.044 |
F-3-4 | 0.030 | 0.05 |
F-3-5 | 0.065 | 0.069 |
Symbols | Explanations |
---|---|
BI | Basicity index |
K | Equilibrium coefficient |
f | Interaction coefficient |
αNSiO2 | SiO2 activity in bulk slag |
αNFeO | FeO activity in bulk slag |
αFeO | Equilibrium FeO activity at interface |
αO | Equilibrium O activity in weld pool |
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Zhang, J.; Zhang, D.; Liu, P. Thermodynamic Nature of SiO2 and FeO in Flux O Potential Control Subject to Submerged Arc Welding Process. Processes 2023, 11, 400. https://doi.org/10.3390/pr11020400
Zhang J, Zhang D, Liu P. Thermodynamic Nature of SiO2 and FeO in Flux O Potential Control Subject to Submerged Arc Welding Process. Processes. 2023; 11(2):400. https://doi.org/10.3390/pr11020400
Chicago/Turabian StyleZhang, Jin, Dan Zhang, and Ping Liu. 2023. "Thermodynamic Nature of SiO2 and FeO in Flux O Potential Control Subject to Submerged Arc Welding Process" Processes 11, no. 2: 400. https://doi.org/10.3390/pr11020400