The transient evolution of nonmetallic inclusions after calcium addition in pipeline steels was investigated with a vacuum induction furnace. Samples were taken at 1, 5, 10, 15, and 20 minutes after ...calcium treatment in both MgO and Al
2
O
3
crucibles. It was found that the total oxygen and the number density of inclusions were increased during calcium modification, while they were dropped to a low level in the last tapped sample. Due to the evaporation of calcium, inclusions were transferred from CaO-CaS to Al
2
O
3
-CaO-CaS, and then to Al
2
O
3
-CaO. The decomposition of CaS was highly dependent on the decrease of the total calcium and the increase of the total oxygen in the steel. Thermodynamic calculation was performed to predict the composition of inclusions considering the effect of the total oxygen and the total calcium and was validated by measurement. The relationship between the content of Al
2
O
3
in inclusions and the ratio of the total calcium and the total oxygen in steels was measured and compared with the calculated one using thermodynamic software Factsage 7.0. The mass-transfer coefficient of the dissolved calcium in the steel was estimated in the range of 2.35 × 10
−4
to 3.53 × 10
−4
m/s.
Coreless induction furnace is one of the most widely used equipment in the steelmaking sector, while the lining refractory are the key factors in determining the lifetime of the induction furnace. ...The multi-physics field dominates the operating conditions of the lining refractory which can be well-studied using numerical simulation techniques. Based on the technique, and adopted frequency domain-transient method, the thermal-electromagnetic flow coupled multi-physical fields is simulated and the effects of multi-physical fields on the furnace lining refractory are analyzed as well, which provides a numerical simulation guiding approach for the design of the lining refractory of induction furnace. The results indicate that the excitation magnetic field distribution dominates the multi-physics field distribution, and shows a concentrated field distribution at the bottom corner and slag line, the inner wall of the furnace lining is influenced by the liquid steel impact, the temperature, velocity and stress at the bottom corner, reach 2046 K, 0.127 m/s and 2.34 × 10
2
MPa respectively. With regards to the simulation results, the service conditions of these two regions and the furnace waist lining should be focused on when designing refractory for induction furnace lining.
AISI 440B martensitic stainless steels reinforced with up to 15 vol% NbC particles were successfully cast using a vacuum induction furnace. Energy dispersive x-ray spectroscopy, scanning electron ...microscopy and electron backscatter diffraction techniques revealed that NbC additions led to a slight decrease in the matrix solid solution Cr content, which was found to have a minor impact on uniform corrosion resistance. An ISO 21988 grade Cr27 martensitic eutectic white cast iron was used to benchmark the wear performance of the composites. Hardness, sliding wear tests, and erosion wear tests against a garnet slurry, showed that the composites could either match or surpass the cast iron despite having a lower total volume fraction of carbide phases. These results show that the proposed martensitic stainless steel composites have immense potential in high wear applications that require some degree of corrosion resistance, such as in the mining and mineral processing industry.
•NbC - AISI 440 stainless steel composites were cast by vacuum induction melting.•NbC had a marginal effect on the corrosion resistance of AISI 440 stainless steels.•NbC was effective in improving hardness, and sliding and erosive wear resistance.•Compared to a Cr27 white cast iron alloy, the composites performed favorably.•The composites are potential alternatives to high-chromium white cast iron alloys.
•Dynamic model for coreless distribution level induction furnace is presented.•The aim is to represent the induction furnace at the start of the melting process.•Field measurements from PCC are used ...to develop the proposed model.•The proposed model is meant for RVC assessment in network connection studies.
This paper proposes a mathematical model for a distribution level, directly fed core-less, induction furnace that can be used for network voltage behavior related studies performed by the network operators. The objective of the model is to represent the dynamic behaviour of the facility when an induction furnace is energized (switched) at the beginning of the melting process. Model development is supported by actual field measurements from PCC to a distribution system. The paper includes a case study and the results indicate that the proposed model offers accurate results for rapid voltage change assessment and it is shown that the model can be successfully used for various load changes and at various voltage levels.
•The 2D axisymmetric coupled numerical model was developed for metal evaporation process within the vacuum induction furnace.•The mathematical model was validated against the experimental data from ...industrial unit.•The rate of evaporation was successfully predicted for several operating conditions.•The surface temperature is a crucial parameter for the mass transport through the molten metal free surface.
This paper discusses a mathematical model for and presents the experimental results of the metal evaporation process in a vacuum induction furnace. An in-house-developed coupling procedure was utilized to predict the electromagnetic, flow and temperature fields in a simplified axisymmetric domain. Evaporation kinetics were simulated by means of a Hertz-Knudsen equation and implemented as source terms in transport equations. The metal vapour above the molten metal bath was described by an additional conservation equation, with gradients of diffusion flux and evaporated metal source terms included. The diffusion flux was the solution of Fick’s law. To fully analyse the evaporation process, several numerical computations were performed to examine the influence of the input power of the inductor, the crucible position inside the copper coil and the amount of charge. The validation of the mathematical description was performed according to aluminium mass loss measurements. A comparison with the experimental results confirmed that the proposed mathematical model of evaporation kinetics can be applied to the evaporation process modelled within a vacuum induction furnace. A numerical case study allowed for the proper identification of operating conditions to intensify the evaporation process within the induction furnace. Moreover, the obtained results confirmed that even small changes in the charge temperature during the evaporation process might have a crucial influence on the evaporation rate.
In order to analyze the possible source of large TiN inclusion for the high strength tire cord steel. The remelting experiment was conducted via vacuum induction furnace in the laboratory and the ...artificially prepared TiN particles which of size 50-74 μm and 100-180 μm were added during the remelting process. Simultaneously, combined with the dissolution kinetic model of TiN particle to make a brief analysis for the genesis of lagre TiN inclusion detected in the wire rod. The results show that the TiN particle which of size 180 μm dissolved in the liquid steel completely at only a few seconds. The TiN inclusions detected in the remelted specimens are all of regular shape, which mainly formed during the solidification process, rather than the added TiN particle which are not completely dissolved. It is supposed that the large TiN inclusion detected in the wire rod most likely spring from the continuous casting mould fluxes.
•A new castable nanostructured alloy (CNA) was manufactured via casting process.•Electroslag remelting process was used to remove lager inclusions and retain the submicron inclusions.•The Ti addition ...to CLAM steel increased the fraction of MX.•Multiscale secondary phases were employed to strength the alloy.
Herein, we report a new castable nanostructured alloy (CNA), which was first melted in a vacuum induction furnace to introduce micron- and submicron-sized inclusions, strengthened by the multiscale secondary phases for fusion reactors. The large micron-scale inclusions are removed, whereas submicron-scale inclusions were retained during an electroslag remelting process. The ingot was subjected to heat treatment at 1050 °C for 0.5 h followed by heating at 650 °C for 1.5 h to obtain tempered martensite along with the nanosized (Ti, W) carbides. The improvement in the mechanical properties of the sample treated at 750 °C was attributed to the removal of blocky Y-rich inclusions along with the strengthening of the submicron-sized Y2O3 oxides. The performance of the sample treated at 650 °C was explained by the precipitation of the fine (Ti, W) carbides.
•Similar primary zirconia properties by speed-sintering as conventional sintering.•Speed-sintering 3Y-TZP decreased its translucency but not that of 5Y-PSZ.•Speed-sintering lowered the mechanical ...reliability of 3Y-TZP and 5Y-PSZ zirconia.
To evaluate the performance of zirconia ceramics sintered in a speed sintering induction furnace by comprehensive understanding of their optical and mechanical properties, microstructure, phase composition and aging stability, in comparison to ceramics sintered in a conventional furnace.
Speed sintered (SS) Katana STMLSS (Kuraray Noritake) (total thermal cycle/sintering time/dwell temperature: 30min/16min/1560°C) and CEREC Zirconia (CEREC ZrSS) (Dentsply Sirona) (15min/2min/1578°C) were compared to conventionally sintered (CS) Katana STMLCS (6.8h/2h/1550°C) and inCoris TZICS (4h/2h/1510°C). The translucency parameter (TP) and contrast ratio (CR) were measured with a spectrophotometer. The chemical composition of the materials was determined by XRF and phase composition was characterized using XRD. Hydrothermal aging behavior was evaluated by measuring the tetragonal-to-monoclinic ZrO2 phase transformation after accelerated hydrothermal aging in steam at 134°C. The indentation fracture toughness, Vickers hardness and biaxial strength of the sintered ceramics were assessed.
Speed and conventionally sintered zirconia revealed similar density, microstructure, average strength and hydrothermal aging stability. Both Katana STMLSS/CS 5Y-PSZ ceramics were characterized with a higher content of cubic phase (≈53wt%), which resulted in a higher amount of Y2O3 in the remaining tetragonal ZrO2 phases compared to the 3Y-TZP CEREC ZrSS and inCoris TZICS (8 and 20wt%, respectively). The sintering program did not affect the hydrothermal aging behavior of Katana STMLSS and CEREC ZrSS. TP of Katana STMLSS (TP≈32) was not affected by speed sintering, while the translucency of CEREC ZrSS (TP=14) was significantly reduced. Hardness, fracture toughness and Weibull characteristic strength of Katana STMLSS and CEREC ZrSS also reached the optimal level, but speed sintering substantially lowered their mechanical reliability.
Speed sintering of 3Y-TZP and 5Y-PSZ in a speed sintering induction oven appeared suitable for clinical applications. However, further studies should focus on improving of translucency and mechanical reliability of the speed-sintered zirconia ceramics.
The present work reports the fabrication of Mg
89
RE
11
(RE = Pr, Sm, Nd) alloys by a vacuum induction furnace. The phase analysis, structure characterization and microstructure observation of Mg
89
...RE
11
alloys were carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). There exhibits a multiphase microstructure in the as-cast Mg
89
RE
11
(RE = Pr, Nd, Sm) alloys from the comprehensive analysis made from XRD and SEM, which are containing the major phase (RE
5
Mg
41
) and several secondary phases (REMg
3
and REMg
12
). The detections of XRD and TEM reveal that these experimental alloys turn into a MgH
2
nanocrystalline composite with equably distributed RE hydride nanoparticles after hydriding and this MgH
2
major phase turns into a Mg nanocrystalline after dehydriding. The determination results of the hydrogen storage kinetics show that adding the rare earth element (Pr, Sm and Nd) ameliorates the hydriding and dehydriding kinetics of the Mg-based alloys dramatically. The hydrogen desorption activation energy
E
a
(de) of Mg
89
Pr
11
, Mg
89
Nd
11
, Mg
89
Sm
11
are 140.595, 139.191, 135.280 kJ mol
−1
H
2
, respectively. Specially, the hydrogen storage capacity (wt%) of Mg
89
Sm
11
alloy that added Sm element can reached 5 wt%. The improvement of the hydrogen storage performance of Mg
89
RE
11
alloys can be principally ascribed to the RE hydride nanoparticles facilitating the hydriding and dehydriding reactions.
Improving hydrogen storage performance of Mg
89
RE
11
alloys attributes to the RE hydride nanoparticles facilitate the hydriding and dehydriding reactions.
As a key part of investigating a new proposed Ti-alloy production process, Ti-Al alloys were produced by aluminothermic reduction experiments at 1973 K in Al
2
O
3
crucibles. Besides, pure Ti and Al ...were melted inside CaO crucibles at 1973 K to investigate the possibility of melt refining in equilibrium with CaO. The experiments were carried out in a vacuum induction furnace under argon gas at atmospheric pressure. The experimental results were proved by thermodynamic evaluations including also literature data. The correlation of oxygen and aluminum in Ti melt with 11 to 23 wt pct Al in contact with Al
2
O
3
was assessed as
3
ln
X
O
=
-
2
ln
X
Al
-
9.1
±
0.4
.
This correlation in Ti melt with 3 to 10 wt pct Al in contact with CaO was
3
ln
X
O
=
-
2
ln
X
Al
-
14.9
±
0.3
.
Partial molar excess Gibbs free energies of mixing and combinations thereof in Ti-rich Ti-Al-O-Ca melt were assessed as
R
T
ln
(
γ
Al
2
·
γ
O
3
)
=
-
894
±
6
(
kJ
/
mol
)
,
R
T
ln
γ
Ca
·
γ
O
=
-
195
±
4
(
kJ
/
mol
)
,
R
T
ln
γ
O
=
-
258
±
6
(
kJ
/
mol
)
,
R
T
ln
γ
Ca
=
62
±
7
(
kJ
/
mol
)
.
The activity of Al
2
O
3
in CaO-saturated slag was assessed as 0.003 ± 0.001. The changes of Gibbs free energy for the dissolution of 1 wt pct oxygen and 1 wt pct calcium in Ti-Al melt were estimated as −630 ± 6 and −11 ± 7 (kJ/mol), respectively. A model was developed and applied to calculate the basic data for refining Ti-Al alloy.
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