The rapid growth of semiconductor,photovoltaic,and other emerging industries has led to a sharp increase in the demand for high-purity quartz in China,particularly 4N5-grade(99.995%pure SiO_(2)).However,heavy reliance...The rapid growth of semiconductor,photovoltaic,and other emerging industries has led to a sharp increase in the demand for high-purity quartz in China,particularly 4N5-grade(99.995%pure SiO_(2)).However,heavy reliance on imported high-purity quartz poses a significant risk to the security of key national strategic industries.To address this challenge,China is focusing on identifying domestic sources of high-purity quartz and developing efficient evaluation methods.This study investigates the inclusion content in three types of quartz:pegmatite,vein quartz,and white granite.A grading system based on the transmittance of quartz grains was established by analyz-ing the number of inclusions.Five quartz ore samples from different regions were purified,and the resulting concentrates were analyzed using inductively coupled plasma mass spectrometry(ICP-MS).The relationships among the inclusion content of raw quartz,impurity composition of purified quartz,and quality of sintered fused quartz products were examined.The findings demonstrate that quartz with fewer inclusions results in lower impurity levels after purification,higher SiO_(2)purity,and more translucent glass,as confirmed by firing tests.Herein,this study establishes a clear connection between quartz inclusions and the overall quality of high-purity quartz.The pro-posed approach enables the rapid assessment of quartz deposit quality by identifying inclusions,offering a practical and efficient method for locating high-quality quartz resources.展开更多
0 INTRODUCTION Sulfur(S)and carbon(C)are essential volatile elements in both interior and surficial systems of the Earth.The cycling of S and C in subduction zones plays a fundamental role in modulating global S-C flu...0 INTRODUCTION Sulfur(S)and carbon(C)are essential volatile elements in both interior and surficial systems of the Earth.The cycling of S and C in subduction zones plays a fundamental role in modulating global S-C fluxes and exerts a significant influence on the climate evolution,mantle's redox budget,and ore deposit formation(Bekaert et al.,2021).展开更多
The extreme removal of SiO2 and MnO inclusions in 304 stainless steel in supergravity fields was investigated using an inhouse high-temperature supergravity equipment.The influences of the gravity coefficient and sepa...The extreme removal of SiO2 and MnO inclusions in 304 stainless steel in supergravity fields was investigated using an inhouse high-temperature supergravity equipment.The influences of the gravity coefficient and separation time on the removal efficiency of the inclusions were studied.After supergravity treatment,the inclusions migrated to the top of the sample and formed large aggregates.Meanwhile,the lower part of the sample was purified considerably and appeared significantly cleaner than the raw material.At the gravity coefficient of 500 and separation time of 600 s,the total oxygen content at the bottom of the sample(position E)decreased from 240 to 28 ppm.This corresponded to a total oxygen removal rate of 88.33%.The volume fraction and number density of inclusions exhibited a gradient distribution along the supergravity direction,with values of 8.5%and 106 mm^(-2) at the top of the sample(position A)and 0.06%and 22 mm^(-2) at its bottom.展开更多
The specific distribution characteristics of inclusions along with the sliver defect were analyzed in detail to explain the formation mechanism of the sliver defect on the automobile exposed panel surface.A quantitati...The specific distribution characteristics of inclusions along with the sliver defect were analyzed in detail to explain the formation mechanism of the sliver defect on the automobile exposed panel surface.A quantitative electrolysis method was used to compare and evaluate the three-dimensional morphology,size,composition,quantity,and distribution of inclusions in the defect and non-defect zone of automobile exposed panel.The Al2O3 inclusions were observed to be aggregated or chain-like shape along with the sliver defect of about 3–10μm.The aggregation sections of the Al2O3 inclusions are distributed discretely along the rolling direction,with a spacing of 3–7 mm,a length of 6–7 mm,and a width of about 3 mm.The inclusion area part is 0.04%–0.16%with an average value of 0.08%,the inclusion number density is 40 mm−2 and the inclusion average spacing is 25.13μm.The inclusion spacing is approximately 40–160μm,with an average value of 68.76μm in chain-like inclusion parts.The average area fraction and number density of inclusions in the non-defect region were reduced to about 0.002%and 1–2 mm^−2,respectively,with the inclusion spacing of 400μm and the size of Al2O3 being 1–3μm.展开更多
Non-metallic inclusions in steel are a significant challenge,affecting material properties and leading to issues such as stress concentration,cracking,and accelerated corrosion.Current methods for removing inclusions,...Non-metallic inclusions in steel are a significant challenge,affecting material properties and leading to issues such as stress concentration,cracking,and accelerated corrosion.Current methods for removing inclusions,including bubble,electromagnetic stirring,filtration separation,fluid flow,and sedimentation,often struggle with the removal of fine inclusions.Apart from these known methods,pulsed electric current(PEC),as an emerging technology,has demonstrated immense potential and environmental advantages.PEC offers adjustable current parameters and simple equipment,making it an attractive alternative to traditional methods.Its green energy-saving features and excellent results in regulating inclusion morphology and migration,as well as inhibiting submerged entry nozzle(SEN)clogging,make it a promising technology.In comparison to continuous current technology,PEC has shown significant advantages in regulating inclusions,not only improving purification efficiency but also demonstrating outstanding performance in flow stability and energy consumption.The ability of PEC to efficiently reduce inclusion numbers enhances the purity and quality of molten steel,improving its mechanical properties.Currently,the theoretical basis for controlling the movement of inclusions by current is mainly composed of three major theories:the double electric layer theory,electromagnetic force reverse separation theory,and electric free energy drive theory.These theories together form an important framework for researchers to understand and optimize the behavior of impurity movement controlled by electric current.Looking ahead,PEC is expected to pave the way for new solutions in directional regulation of inclusion migration,efficient inclusion removal,SEN clogging prevention,and the purification of molten steel.展开更多
The dissolution behavior of complex inclusions in refining slag was studied using confocal laser scanning microscope.Based on the dissolution curve of complex inclusions,the main rate-limiting link of CaO-SiO_(2)-Al_(...The dissolution behavior of complex inclusions in refining slag was studied using confocal laser scanning microscope.Based on the dissolution curve of complex inclusions,the main rate-limiting link of CaO-SiO_(2)-Al_(2)O_(3)complex inclusions was the diffusion in the molten slag.The dissolution rate of CaO-SiO_(2)-Al_(2)O_(3)complex inclusions was affected by the composition and size of inclusion.The functional relationship between the dimensionless inclusion capacity(Zh)and the dimensionless dissolution rate(Ry)of CaO-SiO_(2)-Al_(2)O_(3)complex inclusions was calculated as Ry=2.10×10^(-6)Zh^(0.160),while it was Ry=2.10×10^(-6)Zh^(0.0087)for Al_(2)O_(3)-CaO complex inclusions.On this basis,the complete dissolution time and rate of the complex inclusions were calculated by using the function relation between the Zh and Ry numbers.展开更多
The characteristics of nonmetallic inclusions formed during steel production have a significant influence on steel performance.In this paper,studies on inclusions using confocal scanning laser microscopy(CSLM)are revi...The characteristics of nonmetallic inclusions formed during steel production have a significant influence on steel performance.In this paper,studies on inclusions using confocal scanning laser microscopy(CSLM)are reviewed and summarized,particularly the col-lision of various inclusions,dissolution of inclusions in liquid slag,and reactions between inclusions and steel.Solid inclusions exhibited a high collision tendency,whereas pure liquid inclusions exhibited minimal collisions because of the small attraction force induced by their<90°contact angle with molten steel.The collision of complex inclusions in molten steel was not included in the scope of this study and should be evaluated in future studies.Higher CaO/Al_(2)O_(3)and CaO/SiO_(2)ratios in liquid slag promoted the dissolution of Al_(2)O_(3)-based in-clusions.The formation of solid phases in the slag should be prevented to improve dissolution of inclusions.To accurately simulate the dissolution of inclusions in liquid slag,in-situ observation of the dissolution of inclusions at the steel-slag interface is necessary.Using a combination of CSLM and scanning electron microscopy-energy dispersive spectroscopy,the composition and morphological evolution of the inclusions during their modification by the dissolved elements in steel were observed and analyzed.Although the in-situ observa-tion of MnS and TiN precipitations has been widely studied,the in-situ observation of the evolution of oxide inclusions in steel during so-lidification and heating processes has rarely been reported.The effects of temperature,heating and cooling rates,and inclusion character-istics on the formation of acicular ferrites(AFs)have been widely studied.At a cooling rate of 3-5 K/s,the order of AF growth rate in-duced by different inclusions,as reported in literature,is Ti-O<Ti-Ca-Zr-Al-O<Mg-O<Ti-Zr-Al-O<Mn-Ti-Al-O<Ti-Al-O<Zr-Ti-Al-O.Further comprehensive experiments are required to investigate the quantitative relationship between the formation of AFs and inclusions.展开更多
Influenced by Late Cretaceous tectonic uplift,fluid inclusion techniques were employed to determine the hydrocarbon accumulation stages of the Chang 7_(3) sub-member in the Zhijing-Ansai area.There were two fluorescen...Influenced by Late Cretaceous tectonic uplift,fluid inclusion techniques were employed to determine the hydrocarbon accumulation stages of the Chang 7_(3) sub-member in the Zhijing-Ansai area.There were two fluorescent oil inclusions in the Chang 7_(3) sub-member.The green fluorescent oil inclusions indicated the relatively low-maturity oil,the homogenization temperatures of coeval aqueous inclusions were 83.8-89.5℃.The blue fluorescent oil inclusions indicated the relatively high-maturity oil,the homogenization temperatures of coeval aqueous inclusions exhibited two peaks which were 90.6-109.4℃and 110.1-137.4℃.Combining the burial-thermal history of four wells,there were three stages of hydrocarbon accumulation.A smallscale charging of the relatively low-maturity oil occurred around 131-122 Ma.During the large-scale charging of the high-maturity oil,the hydrocarbon generation of source rock peaked(c.114 to 100 Ma).Late tectonic uplift resulted in an oil adjustment stage(88-72 Ma),corresponding to the high-maturity oil charging time.展开更多
In order to mitigate the harm of alumina,calcium aluminate,and magnesium aluminum spinel inclusions on the fatigue performance of bearing steel,the effect of Ce-Mg composite treatment on the cleanliness of silicon-kil...In order to mitigate the harm of alumina,calcium aluminate,and magnesium aluminum spinel inclusions on the fatigue performance of bearing steel,the effect of Ce-Mg composite treatment on the cleanliness of silicon-killed GCr15 bearing steel and the evolution of Ce-Mg-Mn-O-S composite inclusions during heat treatment of the steels at 1523 K were investigated in this present work.The results indicate that the cleanliness of S2 with 0.0045 wt%Ce and 0.0016 wt%Mg is better than that in S1 with0.0020 wt%Ce and 0.0011 wt%Mg,which is attributed to the more effective removal of Ce-Mg-Mn-O-S composite inclusions,with help of good aggregation capacity of Ce-containing inclusions and small volume density of Mg-containing inclusions,due to the increase of rare earth and magnesium content.The aspect ratio and area fraction of the Ce-Mg-Mn-O-S composite inclusions in as-cast steel decrease significantly with isothermal treatment at 1523 K for 150 min,due to the effect of(ⅰ)Ostwald aging mechanism of inclusions and(ⅱ)sulfide solid solution during isothermal treatment.With the increase of isothermal treatment time from 150 to 550 min,the aspect ratio and area fraction of the inclusions in SO(untreated steel)and S1 decrease slightly,because spheroidization and solid solution of inclusions reach their basic equilibrium at 1523 K.However,the aspect ratio and area fraction of the Ce-Mg-Mn-O-S composite inclusions in S2 actually increase,and the inclusions evolve into three-phase(two-phase)inclusions,which is attributed to(ⅲ)transformation of phase compositions in inclusions and interfacial reaction between inclusions and steel matrix during isothermal heating.Therefore,the control of inclusions in silicon-killed bearing steel with Ce and Mg composite treatment should be combined with specific heat treatment processes and appropriate rare earth and magnesium contents,to minimize the damage of inclusions on the fatigue performance of bearing steel products.展开更多
To mitigate the harmful effects of Al_(2)O_(3) inclusions in steel,it is necessary to conduct comprehensive research on the mechanisms and kinetic laws of Al_(2)O_(3) inclusion modification by Ce.Combined with laborat...To mitigate the harmful effects of Al_(2)O_(3) inclusions in steel,it is necessary to conduct comprehensive research on the mechanisms and kinetic laws of Al_(2)O_(3) inclusion modification by Ce.Combined with laboratory experiments,first-principles calculations,and molecular dynamics simulations,the kinetic model of Ce modification for Al_(2)O_(3) inclusions was established.Based on first-principles calculations,differential charge analysis,density of states analysis,and adsorption energy analysis were performed on the transformation process from Al_(2)O_(3) to CeAlO_(3) at the atomic scale,and the microscopic transformation mechanism of inclusions at the atomic scale was obtained.Molecular dynamics simulations and the solution of mean square displacement function show that the diffusion coefficient for Ce atoms was 2.169×10^(−4) cm^(2)/s,which agreed well with experimental results.In this model,the rate-determining step is the diffusion of Ce atoms across Ce–Al–O inclusions.The relationship between the conversion rate,refining time,and initial radius was discussed.A refining time of 60 s can completely transform Al_(2)O_(3) inclusions less than 2.56μm into CeAlO_(3) inclusions,while refining time of 1200 s is sufficient to modify inclusions size below 11.47μm.展开更多
Model calculations and laboratory experiments were conducted to investigate the influence of surface tension of the molten steel on the agglomeration trend of Al_(2)O_(3) inclusions.The agglomeration trends of inclusi...Model calculations and laboratory experiments were conducted to investigate the influence of surface tension of the molten steel on the agglomeration trend of Al_(2)O_(3) inclusions.The agglomeration trends of inclusions were compared using the calculated attractiveness.When the S content in the steel increased from 2.7×10^(-6) to 789×10^(-6),the surface tension of the molten steel decreased from 1.91 to 1.39 N/m,while the attractive force between inclusions increased from 5×10^(-18) to 5×10^(-16) N,and the critical collision distance of Al_(2)O_(3) inclusions gradually increased from 30 to 70μm.A model of the relationship between the capillary force of inclusions and S content in steel was established.It was found that the capillary force calculated by the model showed the same trend as the attractive force obtained from experiments,and an increase in the S content promoted the attraction between inclusions.展开更多
Formation and evolution of inclusions in low-aluminum Ti-containing 51CrV4 spring steel under BOF(basic oxygen furnace)–LF(ladle furnace)–CC(continuous casting)process were investigated by industrial trials and ther...Formation and evolution of inclusions in low-aluminum Ti-containing 51CrV4 spring steel under BOF(basic oxygen furnace)–LF(ladle furnace)–CC(continuous casting)process were investigated by industrial trials and thermodynamic calculations.During LF refining,deoxidation products including Al_(2)O_(3),Al_(2)O_(3)–Ti_(3)O_(5)–SiO_(2)–MnO and Al_(2)O_(3)–SiO_(2)–MnO are modified as MgO–Al_(2)O_(3),CaO–Al_(2)O_(3)–SiO_(2),CaO–Al_(2)O_(3)–MgO and CaO–Al_(2)O_(3)–SiO_(2)–MgO.When reoxidation during ladle casting is quite serious,inclusions such as Al_(2)O_(3),Al_(2)O_(3)–Ti_(3)O_(5)–SiO_(2)–MnO,and Al_(2)O_(3)–SiO_(2)–MnO may regenerate.A handful of Ti carried by alloy into liquid steel has less influence on inclusions during LF refining;Ti-containing inclusions mainly transiently exist as an intermediate product of deoxidation process and then are gradually modified by[Al],[Ca]or[Mg].Thermodynamic calculation and experimental results reveal that tundish flux is the main source of reoxidation in ladle casting process.Further calculations taking into account of the influence of inclusions before casting indicate that reoxidation within a certain of degree leads to the generation of a large amount of high melting point inclusions including CaO·2MgO·8Al_(2)O_(3),CaO·MgO·7Al_(2)O_(3),MgO·Al_(2)O_(3),CaO·6Al_(2)O_(3)and Al_(2)O_(3)in molten steel,which is basically consistent with experimental results,and more high melting point inclusions will generate as reoxidation becomes severer.On this basis,severer reoxidation will deplete[Si],[Mn],and[Ti]in steel melt,resulting in the formation of liquid inclusions composed of Al_(2)O_(3)–Ti_(3)O_(5)–SiO_(2)–MnO(–CaO).These results are of guiding significance for controlling inclusions in Al-killed Ti-containing spring steel.展开更多
The micro-area characterization experiments like scanning Kelvin probe force microscope(SKPFM)and Kernel average misorientation have the defects of complex sample preparation and occasional errors in test results,whic...The micro-area characterization experiments like scanning Kelvin probe force microscope(SKPFM)and Kernel average misorientation have the defects of complex sample preparation and occasional errors in test results,which makes it impossible to accurately and quickly analyze the pitting behavior induced by inclusions in some cases,prompting attempts to turn to simulation calculation research.The method of calculating band structure and work function can be used to replace current-sensing atomic force microscopy and SKPFM to detect the potential and conductivity of the sample.The band structure results show that Al_(2)O_(3) inclusion is an insulator and non-conductive,and it will not form galvanic corrosion with the matrix.Al_(2)O_(3) inclusion does not dissolve because its work function is higher than that of the matrix.Moreover,the stress concentration of the matrix around the inclusion can be characterized by first-principles calculation coupled with finite element simulation.The results show that the stress concentration degree of the matrix around Al_(2)O_(3) inclusion is serious,and the galvanic corrosion is formed between the high and the low stress concentration areas,which can be used to explain the reason of the pitting induced by Al_(2)O_(3) inclusions.展开更多
The formation of large-sized inclusions cluster severely impacts the continuous casting process and product quality of titanium-containing steel.Thermodynamic calculations were initially conducted to predict the forma...The formation of large-sized inclusions cluster severely impacts the continuous casting process and product quality of titanium-containing steel.Thermodynamic calculations were initially conducted to predict the formation of various complex oxide inclusions,namely Al_(2)O_(3),TiO_(x)and Al-Ti-O.Based on that,laboratory-scale experiments were designed to prepare samples with a single type of inclusions.Then,the scanning electron microscope-energy dispersive spectrometer was used for quantitative characterization.Subsequently,the agglomeration behavior of inclusions in Fe-Al-Ti-O melt was observed in situ by high-temperature confocal laser scanning microscopy.Furthermore,a quantitative analysis of the agglomeration characteristics of the various inclusions was conducted based on the attractive forces in accordance with Newton's second law and the capillary forces as described by the Kralchevsky-Paunov model.The results indicate that the size of Al_(2)O_(3)inclusions is larger than that of TiO_(x)and Al-Ti-O,but the number density of TiO_(x)is the highest.Based on the in situ observation and the theoretical calculation,Al_(2)O_(3),TiO_(x)and Al-Ti-O inclusions can all agglomerate into large-sized clusters without segregation,but the agglomeration tendency of Al_(2)O_(3)and TiO_(x)is stronger than that of Al-Ti-O.The attractive force between Al_(2)O_(3)inclusions’pair is the largest,ranging from 2.26×10^(-15)to 6.12×10^(-14)N,followed by TiO_(x)(7.13×10^(-16)to 3.56×10^(-14)N)and Al-Ti-O(1.16×10^(-17)to 3.77×10^(-16)N).展开更多
High-temperature confocal scanning laser microscopy(HT-CSLM)is a potent methodology for investigating various phenomena in the field of metallurgy.Initially applied to the observation of solid phase transformations an...High-temperature confocal scanning laser microscopy(HT-CSLM)is a potent methodology for investigating various phenomena in the field of metallurgy.Initially applied to the observation of solid phase transformations and solidification,this method has gained traction in the field of non-metallic inclusion in steels in recent years.An overview of the experimental capabilities of HT-CSLM and the most important results of recent investigations regarding the topics of clean steel production are provided.It includes the formation of intragranular acicular ferrite(IAF)from the surface of non-metallic inclusions during the continuous cooling and heat treatment,which can be especially beneficial in the toughness of heat-affected zones of welded pieces.Furthermore,the investigation of agglomeration mechanisms of non-metallic inclusions(NMIs)in liquid steel is discussed to improve the insight into attraction forces between particles and clogging phenomena during continuous casting.Also,the dissolution of NMIs in various steelmaking slags can be observed by HT-CSLM to compare dissolution rates and mechanisms of NMI,where significant influences of temperature and chemical composition of the slag were shown.Last but not least,the experimental work regarding the interface between steel and slag is discussed,where novel techniques are currently being developed.A comprehensive summary of experimental techniques using HT-CSLM equipment to investigate different interactions of NMIs with steel and slag phases is compiled.展开更多
The instantaneous morphological transition of triangular Al_(2)O_(3) particles with various sizes in the molten Ca-treated steel was observed using a confocal scanning laser microscope at the steelmaking temperature.T...The instantaneous morphological transition of triangular Al_(2)O_(3) particles with various sizes in the molten Ca-treated steel was observed using a confocal scanning laser microscope at the steelmaking temperature.The composition of inclusions at different times was analyzed using scanning electron microscopy-energy dispersive spectroscopy.The shape evolution of particles was characterized by the shape parameter of overall regularity.It was found that the overall regularity of particles gradually increased with time during the calcium treatment.The geometry of particles tended to be more rounded and regular as the overall regularity increased during the modification process.An empirical formula was proposed to predict the composition of inclusion particles based on their overall regularity during the calcium treatment.When the CaO/Al_(2)O_(3) mass ratio in the particle increased to 0.451,the particle was considered an ideal spherical calcium aluminate inclusion with the overall regularity of 1.Smaller particle sizes promoted the transformation of Al_(2)O_(3) inclusions to spherical calcium aluminates during the calcium treatment.展开更多
We present the design of two interacting harmonic non-elliptical compressible liquid inclusions embedded in an infinite isotropic elastic matrix subjected to uniform remote in-plane stresses.The original constant mean...We present the design of two interacting harmonic non-elliptical compressible liquid inclusions embedded in an infinite isotropic elastic matrix subjected to uniform remote in-plane stresses.The original constant mean stress(or the first invariant of the stress tensor)in the matrix remains undisturbed in the presence of the two harmonic liquid inclusions.The two non-elliptical liquid-solid interfaces are described by a fourparameter conformal mapping function that maps the doubly connected domain occupied by the matrix onto an annulus in the image plane.The closed-form expressions for the internal uniform hydrostatic stress fields within the two liquid inclusions are obtained.The hoop stresses are uniformly distributed along the two liquid-solid interfaces on the matrix side.展开更多
Dissolution kinetics of CaO·2Al_(2)O_(3)(CA_(2))particles in a synthetic CaO-Al_(2)O_(3)-SiO_(2)steelmaking slag system have been investigated using the high-temperature confocal laser scanning microscope.Effects...Dissolution kinetics of CaO·2Al_(2)O_(3)(CA_(2))particles in a synthetic CaO-Al_(2)O_(3)-SiO_(2)steelmaking slag system have been investigated using the high-temperature confocal laser scanning microscope.Effects of temperature(i.e.,1500,1550,and 1600℃)and slag composition on the dissolution time of CA_(2)particles are investigated,along with the time dependency of the projection area of the particle during the dissolution process.It is found that the dissolution rate was enhanced by either an increase in temperature or a decrease in slag viscosity.Moreover,a higher ratio of CaO/Al_(2)O_(3)(C/A)leads to an increased dissolution rate of CA_(2)particle at 1600℃.Thermodynamic calculations suggested the dissolution product,i.e.,melilite,formed on the surface of the CA_(2)particle during dissolution in slag with a C/A ratio of 3.8 at 1550℃.Scanning electron microscopy equipped with energy dispersive X-ray spectrometry analysis of as-quenched samples confirmed the dissolution path of CA_(2)particles in slags with C/A ratios of 1.8 and 3.8 as well as the melilite formed on the surface of CA_(2)particle.The formation of this layer during the dissolution process was identified as a hindrance,impeding the dissolution of CA_(2)particle.A valuable reference for designing or/and choosing the composition of top slag for clean steel production is provided,especially using calcium treatment during the secondary refining process.展开更多
The quality of stainless steel is closely related to the deformability of inclusions,which is significantly affected by their compositions.The present study first inve stigated the evolution of inclusion compositions ...The quality of stainless steel is closely related to the deformability of inclusions,which is significantly affected by their compositions.The present study first inve stigated the evolution of inclusion compositions in AI-killed steel with rare earth-alkali metals(Ca or Mg)combined treatme nt through four laboratory-scale experiments.The Ce contents in the final steel are 0.0080 wt%,0.015 wt%,0.016 wt%and 0.010 wt%,respectively.The Mg content is 0.0014 wt%in Ce-Mg combined treated steel,and the Ca content is0.0015 wt%in Ce-Ca combined treated steel.The deformability of inclusions in both Ce_(2)O_(3)-Al_(2)O_(3)-CaO and Ce_(2)O_(3)-Al_(2)O_(3)-MgO systems was subsequently evaluated by calculating their Young's modulus at low temperature.The results show that irregular Al_(2)O_(3)and MgAl_(2)O_(4)with poor deformability are modified to CeAlO_(3)and Ce_(2)O_(3)by Ce treatment,resulting in the decrease of Young's modulus of inclusions.The deformability of inclusions is further improved due to the transformation from lumped-like CeAlO_(3)to spherical CaO-Al_(2)O_(3)-Ce_(2)O_(3)caused by Ca treatment,and some of these inclusions are the ones with low liquidus temperature.Thermodynamic analysis was used to discuss the control condition of the formation and evolution of inclusions.Accordingly,the appropriate addition amounts of Al,Mg,Ce,and Ca are expected to control inclusion compositions and properties,including deformability and liquidus temperature,thereby improving the steel performance.展开更多
The transformation of inclusions was studied when control technology of refining top slag in ladle furnace was used in X80 pipeline steelmaking.Sufficient amount of aluminum was added to experimental heats for final d...The transformation of inclusions was studied when control technology of refining top slag in ladle furnace was used in X80 pipeline steelmaking.Sufficient amount of aluminum was added to experimental heats for final deoxidation during BOF tapping,and then the refining top slag with high basicity and strong reducibility was adopted to transform Al 2 O 3 to inclusions with low melting point.The results show that the composition of inclusions changes in order of "Al 2 O 3 → MgO-Al 2 O 3 system→ CaO-MgO-Al 2 O 3 system→ CaO-Al 2 O 3 system".And the inclusions after LF refining are liquid or semi-liquid state at the temperature of steelmaking,which are easily removable to obtain high cleanliness steel by collision,agglomeration and flotation.展开更多
基金financially supported by the Consulting Research Project of the Chinese Academy of Engineering,China(Nos.2024-XBZD-10 and 2024-XZ-20).
文摘The rapid growth of semiconductor,photovoltaic,and other emerging industries has led to a sharp increase in the demand for high-purity quartz in China,particularly 4N5-grade(99.995%pure SiO_(2)).However,heavy reliance on imported high-purity quartz poses a significant risk to the security of key national strategic industries.To address this challenge,China is focusing on identifying domestic sources of high-purity quartz and developing efficient evaluation methods.This study investigates the inclusion content in three types of quartz:pegmatite,vein quartz,and white granite.A grading system based on the transmittance of quartz grains was established by analyz-ing the number of inclusions.Five quartz ore samples from different regions were purified,and the resulting concentrates were analyzed using inductively coupled plasma mass spectrometry(ICP-MS).The relationships among the inclusion content of raw quartz,impurity composition of purified quartz,and quality of sintered fused quartz products were examined.The findings demonstrate that quartz with fewer inclusions results in lower impurity levels after purification,higher SiO_(2)purity,and more translucent glass,as confirmed by firing tests.Herein,this study establishes a clear connection between quartz inclusions and the overall quality of high-purity quartz.The pro-posed approach enables the rapid assessment of quartz deposit quality by identifying inclusions,offering a practical and efficient method for locating high-quality quartz resources.
基金financially supported by the National Natural Science Foundation of China(Nos.92355301,42302061)the China Postdoctoral Science Foundation(No.2023M743471)+1 种基金the Key Research Program of the Institute of Geology and Geophysics,Chinese Academy of Sciences(No.IGGCAS-202204)the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.Y2021026)。
文摘0 INTRODUCTION Sulfur(S)and carbon(C)are essential volatile elements in both interior and surficial systems of the Earth.The cycling of S and C in subduction zones plays a fundamental role in modulating global S-C fluxes and exerts a significant influence on the climate evolution,mantle's redox budget,and ore deposit formation(Bekaert et al.,2021).
基金supported by the National Natural Science Foundation of China(No.52174275).
文摘The extreme removal of SiO2 and MnO inclusions in 304 stainless steel in supergravity fields was investigated using an inhouse high-temperature supergravity equipment.The influences of the gravity coefficient and separation time on the removal efficiency of the inclusions were studied.After supergravity treatment,the inclusions migrated to the top of the sample and formed large aggregates.Meanwhile,the lower part of the sample was purified considerably and appeared significantly cleaner than the raw material.At the gravity coefficient of 500 and separation time of 600 s,the total oxygen content at the bottom of the sample(position E)decreased from 240 to 28 ppm.This corresponded to a total oxygen removal rate of 88.33%.The volume fraction and number density of inclusions exhibited a gradient distribution along the supergravity direction,with values of 8.5%and 106 mm^(-2) at the top of the sample(position A)and 0.06%and 22 mm^(-2) at its bottom.
基金This work was financially supported by the National Natural Science Foundation of China(No.U1960202).
文摘The specific distribution characteristics of inclusions along with the sliver defect were analyzed in detail to explain the formation mechanism of the sliver defect on the automobile exposed panel surface.A quantitative electrolysis method was used to compare and evaluate the three-dimensional morphology,size,composition,quantity,and distribution of inclusions in the defect and non-defect zone of automobile exposed panel.The Al2O3 inclusions were observed to be aggregated or chain-like shape along with the sliver defect of about 3–10μm.The aggregation sections of the Al2O3 inclusions are distributed discretely along the rolling direction,with a spacing of 3–7 mm,a length of 6–7 mm,and a width of about 3 mm.The inclusion area part is 0.04%–0.16%with an average value of 0.08%,the inclusion number density is 40 mm−2 and the inclusion average spacing is 25.13μm.The inclusion spacing is approximately 40–160μm,with an average value of 68.76μm in chain-like inclusion parts.The average area fraction and number density of inclusions in the non-defect region were reduced to about 0.002%and 1–2 mm^−2,respectively,with the inclusion spacing of 400μm and the size of Al2O3 being 1–3μm.
基金supported by the Fundamental Research Funds for the Central Universities(No.FRF-BD-23-01).
文摘Non-metallic inclusions in steel are a significant challenge,affecting material properties and leading to issues such as stress concentration,cracking,and accelerated corrosion.Current methods for removing inclusions,including bubble,electromagnetic stirring,filtration separation,fluid flow,and sedimentation,often struggle with the removal of fine inclusions.Apart from these known methods,pulsed electric current(PEC),as an emerging technology,has demonstrated immense potential and environmental advantages.PEC offers adjustable current parameters and simple equipment,making it an attractive alternative to traditional methods.Its green energy-saving features and excellent results in regulating inclusion morphology and migration,as well as inhibiting submerged entry nozzle(SEN)clogging,make it a promising technology.In comparison to continuous current technology,PEC has shown significant advantages in regulating inclusions,not only improving purification efficiency but also demonstrating outstanding performance in flow stability and energy consumption.The ability of PEC to efficiently reduce inclusion numbers enhances the purity and quality of molten steel,improving its mechanical properties.Currently,the theoretical basis for controlling the movement of inclusions by current is mainly composed of three major theories:the double electric layer theory,electromagnetic force reverse separation theory,and electric free energy drive theory.These theories together form an important framework for researchers to understand and optimize the behavior of impurity movement controlled by electric current.Looking ahead,PEC is expected to pave the way for new solutions in directional regulation of inclusion migration,efficient inclusion removal,SEN clogging prevention,and the purification of molten steel.
基金support from the National Key R&D Program(No.2023YFB3709900)the National Natural Science Foundation of China(Grant No.U22A20171)+1 种基金the High Steel Center at the North China University of Technologythe University of Science and Technology Beijing,China.
文摘The dissolution behavior of complex inclusions in refining slag was studied using confocal laser scanning microscope.Based on the dissolution curve of complex inclusions,the main rate-limiting link of CaO-SiO_(2)-Al_(2)O_(3)complex inclusions was the diffusion in the molten slag.The dissolution rate of CaO-SiO_(2)-Al_(2)O_(3)complex inclusions was affected by the composition and size of inclusion.The functional relationship between the dimensionless inclusion capacity(Zh)and the dimensionless dissolution rate(Ry)of CaO-SiO_(2)-Al_(2)O_(3)complex inclusions was calculated as Ry=2.10×10^(-6)Zh^(0.160),while it was Ry=2.10×10^(-6)Zh^(0.0087)for Al_(2)O_(3)-CaO complex inclusions.On this basis,the complete dissolution time and rate of the complex inclusions were calculated by using the function relation between the Zh and Ry numbers.
基金supported by the National Key R&D Program(No.2023YFB3709900)the National Nature Science Foundation of China(No.U22A20171)+2 种基金China Baowu Low Carbon Metallurgy Innovation Foundation(No.BWLCF202315)the High Steel Center(HSC)at North China University of TechnologyUniversity of Science and Technology Beijing,China.
文摘The characteristics of nonmetallic inclusions formed during steel production have a significant influence on steel performance.In this paper,studies on inclusions using confocal scanning laser microscopy(CSLM)are reviewed and summarized,particularly the col-lision of various inclusions,dissolution of inclusions in liquid slag,and reactions between inclusions and steel.Solid inclusions exhibited a high collision tendency,whereas pure liquid inclusions exhibited minimal collisions because of the small attraction force induced by their<90°contact angle with molten steel.The collision of complex inclusions in molten steel was not included in the scope of this study and should be evaluated in future studies.Higher CaO/Al_(2)O_(3)and CaO/SiO_(2)ratios in liquid slag promoted the dissolution of Al_(2)O_(3)-based in-clusions.The formation of solid phases in the slag should be prevented to improve dissolution of inclusions.To accurately simulate the dissolution of inclusions in liquid slag,in-situ observation of the dissolution of inclusions at the steel-slag interface is necessary.Using a combination of CSLM and scanning electron microscopy-energy dispersive spectroscopy,the composition and morphological evolution of the inclusions during their modification by the dissolved elements in steel were observed and analyzed.Although the in-situ observa-tion of MnS and TiN precipitations has been widely studied,the in-situ observation of the evolution of oxide inclusions in steel during so-lidification and heating processes has rarely been reported.The effects of temperature,heating and cooling rates,and inclusion character-istics on the formation of acicular ferrites(AFs)have been widely studied.At a cooling rate of 3-5 K/s,the order of AF growth rate in-duced by different inclusions,as reported in literature,is Ti-O<Ti-Ca-Zr-Al-O<Mg-O<Ti-Zr-Al-O<Mn-Ti-Al-O<Ti-Al-O<Zr-Ti-Al-O.Further comprehensive experiments are required to investigate the quantitative relationship between the formation of AFs and inclusions.
文摘Influenced by Late Cretaceous tectonic uplift,fluid inclusion techniques were employed to determine the hydrocarbon accumulation stages of the Chang 7_(3) sub-member in the Zhijing-Ansai area.There were two fluorescent oil inclusions in the Chang 7_(3) sub-member.The green fluorescent oil inclusions indicated the relatively low-maturity oil,the homogenization temperatures of coeval aqueous inclusions were 83.8-89.5℃.The blue fluorescent oil inclusions indicated the relatively high-maturity oil,the homogenization temperatures of coeval aqueous inclusions exhibited two peaks which were 90.6-109.4℃and 110.1-137.4℃.Combining the burial-thermal history of four wells,there were three stages of hydrocarbon accumulation.A smallscale charging of the relatively low-maturity oil occurred around 131-122 Ma.During the large-scale charging of the high-maturity oil,the hydrocarbon generation of source rock peaked(c.114 to 100 Ma).Late tectonic uplift resulted in an oil adjustment stage(88-72 Ma),corresponding to the high-maturity oil charging time.
基金Project supported by the National Natural Science Foundation of China(52174323,52231003)。
文摘In order to mitigate the harm of alumina,calcium aluminate,and magnesium aluminum spinel inclusions on the fatigue performance of bearing steel,the effect of Ce-Mg composite treatment on the cleanliness of silicon-killed GCr15 bearing steel and the evolution of Ce-Mg-Mn-O-S composite inclusions during heat treatment of the steels at 1523 K were investigated in this present work.The results indicate that the cleanliness of S2 with 0.0045 wt%Ce and 0.0016 wt%Mg is better than that in S1 with0.0020 wt%Ce and 0.0011 wt%Mg,which is attributed to the more effective removal of Ce-Mg-Mn-O-S composite inclusions,with help of good aggregation capacity of Ce-containing inclusions and small volume density of Mg-containing inclusions,due to the increase of rare earth and magnesium content.The aspect ratio and area fraction of the Ce-Mg-Mn-O-S composite inclusions in as-cast steel decrease significantly with isothermal treatment at 1523 K for 150 min,due to the effect of(ⅰ)Ostwald aging mechanism of inclusions and(ⅱ)sulfide solid solution during isothermal treatment.With the increase of isothermal treatment time from 150 to 550 min,the aspect ratio and area fraction of the inclusions in SO(untreated steel)and S1 decrease slightly,because spheroidization and solid solution of inclusions reach their basic equilibrium at 1523 K.However,the aspect ratio and area fraction of the Ce-Mg-Mn-O-S composite inclusions in S2 actually increase,and the inclusions evolve into three-phase(two-phase)inclusions,which is attributed to(ⅲ)transformation of phase compositions in inclusions and interfacial reaction between inclusions and steel matrix during isothermal heating.Therefore,the control of inclusions in silicon-killed bearing steel with Ce and Mg composite treatment should be combined with specific heat treatment processes and appropriate rare earth and magnesium contents,to minimize the damage of inclusions on the fatigue performance of bearing steel products.
基金supported by the National Natural Science Foundation of China(Nos.52064011,52274331 and 52264041)Guizhou Provincial Basic Research Program(Natural Science)(Nos.ZK[2021]258 and ZK[2023]Zhongdian 020)+6 种基金Guizhou Provincial Key Technology R&D Program(No.[2021]342)Guizhou Provincial Program on Commercialization of Scientific and Technological Achievements(No.[2022]089)supported by Open Project of State Key Laboratory of Advanced Special Steel,Shanghai Key Laboratory of Advanced Ferrometallurgy,Shanghai University(No.SKLASS 2023-08)the Science and Technology Commission of Shanghai Municipality(No.19DZ2270200)supported by State Key Laboratory of Advanced Metallurgy(No.K23-04)China Postdoctoral Science Foundation(No.2023MD744232)Key Research Projects in Higher Education Institutions of Henan Province(No.24B450003).
文摘To mitigate the harmful effects of Al_(2)O_(3) inclusions in steel,it is necessary to conduct comprehensive research on the mechanisms and kinetic laws of Al_(2)O_(3) inclusion modification by Ce.Combined with laboratory experiments,first-principles calculations,and molecular dynamics simulations,the kinetic model of Ce modification for Al_(2)O_(3) inclusions was established.Based on first-principles calculations,differential charge analysis,density of states analysis,and adsorption energy analysis were performed on the transformation process from Al_(2)O_(3) to CeAlO_(3) at the atomic scale,and the microscopic transformation mechanism of inclusions at the atomic scale was obtained.Molecular dynamics simulations and the solution of mean square displacement function show that the diffusion coefficient for Ce atoms was 2.169×10^(−4) cm^(2)/s,which agreed well with experimental results.In this model,the rate-determining step is the diffusion of Ce atoms across Ce–Al–O inclusions.The relationship between the conversion rate,refining time,and initial radius was discussed.A refining time of 60 s can completely transform Al_(2)O_(3) inclusions less than 2.56μm into CeAlO_(3) inclusions,while refining time of 1200 s is sufficient to modify inclusions size below 11.47μm.
基金the National Natural Science Foundation of China(Grant No.U22A20171)the National Key Research and Development Program Project of China(2023YFB3709900)+1 种基金the China Baowu Low Carbon Metallurgical Innovation Fund(BWLCF202315)the Pangang-USTB Vanadium and Titanium Research Institute Research Project,the High Steel Center(HSC)at North China University of Technology,Yanshan University and University of Science and Technology Beijing,China.
文摘Model calculations and laboratory experiments were conducted to investigate the influence of surface tension of the molten steel on the agglomeration trend of Al_(2)O_(3) inclusions.The agglomeration trends of inclusions were compared using the calculated attractiveness.When the S content in the steel increased from 2.7×10^(-6) to 789×10^(-6),the surface tension of the molten steel decreased from 1.91 to 1.39 N/m,while the attractive force between inclusions increased from 5×10^(-18) to 5×10^(-16) N,and the critical collision distance of Al_(2)O_(3) inclusions gradually increased from 30 to 70μm.A model of the relationship between the capillary force of inclusions and S content in steel was established.It was found that the capillary force calculated by the model showed the same trend as the attractive force obtained from experiments,and an increase in the S content promoted the attraction between inclusions.
基金support from the project of Xinjiang Bayi Iron and Steel Co.,Ltd.(No.2022-0460).
文摘Formation and evolution of inclusions in low-aluminum Ti-containing 51CrV4 spring steel under BOF(basic oxygen furnace)–LF(ladle furnace)–CC(continuous casting)process were investigated by industrial trials and thermodynamic calculations.During LF refining,deoxidation products including Al_(2)O_(3),Al_(2)O_(3)–Ti_(3)O_(5)–SiO_(2)–MnO and Al_(2)O_(3)–SiO_(2)–MnO are modified as MgO–Al_(2)O_(3),CaO–Al_(2)O_(3)–SiO_(2),CaO–Al_(2)O_(3)–MgO and CaO–Al_(2)O_(3)–SiO_(2)–MgO.When reoxidation during ladle casting is quite serious,inclusions such as Al_(2)O_(3),Al_(2)O_(3)–Ti_(3)O_(5)–SiO_(2)–MnO,and Al_(2)O_(3)–SiO_(2)–MnO may regenerate.A handful of Ti carried by alloy into liquid steel has less influence on inclusions during LF refining;Ti-containing inclusions mainly transiently exist as an intermediate product of deoxidation process and then are gradually modified by[Al],[Ca]or[Mg].Thermodynamic calculation and experimental results reveal that tundish flux is the main source of reoxidation in ladle casting process.Further calculations taking into account of the influence of inclusions before casting indicate that reoxidation within a certain of degree leads to the generation of a large amount of high melting point inclusions including CaO·2MgO·8Al_(2)O_(3),CaO·MgO·7Al_(2)O_(3),MgO·Al_(2)O_(3),CaO·6Al_(2)O_(3)and Al_(2)O_(3)in molten steel,which is basically consistent with experimental results,and more high melting point inclusions will generate as reoxidation becomes severer.On this basis,severer reoxidation will deplete[Si],[Mn],and[Ti]in steel melt,resulting in the formation of liquid inclusions composed of Al_(2)O_(3)–Ti_(3)O_(5)–SiO_(2)–MnO(–CaO).These results are of guiding significance for controlling inclusions in Al-killed Ti-containing spring steel.
基金supported by the National Natural Science Foundation of China(Nos.52364044 and 52204364)Central Guidance on Local Science and Technology Development Fund Projects of Inner Mongolia Autonomous Region(No.2022ZY0090)Basic Scientific Research Business Expenses of Colleges and Universities in Inner Mongolia Autonomous Region(Nos.2023QNJS011 and 0406082226).
文摘The micro-area characterization experiments like scanning Kelvin probe force microscope(SKPFM)and Kernel average misorientation have the defects of complex sample preparation and occasional errors in test results,which makes it impossible to accurately and quickly analyze the pitting behavior induced by inclusions in some cases,prompting attempts to turn to simulation calculation research.The method of calculating band structure and work function can be used to replace current-sensing atomic force microscopy and SKPFM to detect the potential and conductivity of the sample.The band structure results show that Al_(2)O_(3) inclusion is an insulator and non-conductive,and it will not form galvanic corrosion with the matrix.Al_(2)O_(3) inclusion does not dissolve because its work function is higher than that of the matrix.Moreover,the stress concentration of the matrix around the inclusion can be characterized by first-principles calculation coupled with finite element simulation.The results show that the stress concentration degree of the matrix around Al_(2)O_(3) inclusion is serious,and the galvanic corrosion is formed between the high and the low stress concentration areas,which can be used to explain the reason of the pitting induced by Al_(2)O_(3) inclusions.
基金support of Postdoctoral Fellowship Program of CPSF(GZC20230393)Natural Science Foundation of Liaoning Province in China(2023-BSBA-112)Fundamental Research Funds for the Central Universities(N2425032).
文摘The formation of large-sized inclusions cluster severely impacts the continuous casting process and product quality of titanium-containing steel.Thermodynamic calculations were initially conducted to predict the formation of various complex oxide inclusions,namely Al_(2)O_(3),TiO_(x)and Al-Ti-O.Based on that,laboratory-scale experiments were designed to prepare samples with a single type of inclusions.Then,the scanning electron microscope-energy dispersive spectrometer was used for quantitative characterization.Subsequently,the agglomeration behavior of inclusions in Fe-Al-Ti-O melt was observed in situ by high-temperature confocal laser scanning microscopy.Furthermore,a quantitative analysis of the agglomeration characteristics of the various inclusions was conducted based on the attractive forces in accordance with Newton's second law and the capillary forces as described by the Kralchevsky-Paunov model.The results indicate that the size of Al_(2)O_(3)inclusions is larger than that of TiO_(x)and Al-Ti-O,but the number density of TiO_(x)is the highest.Based on the in situ observation and the theoretical calculation,Al_(2)O_(3),TiO_(x)and Al-Ti-O inclusions can all agglomerate into large-sized clusters without segregation,but the agglomeration tendency of Al_(2)O_(3)and TiO_(x)is stronger than that of Al-Ti-O.The attractive force between Al_(2)O_(3)inclusions’pair is the largest,ranging from 2.26×10^(-15)to 6.12×10^(-14)N,followed by TiO_(x)(7.13×10^(-16)to 3.56×10^(-14)N)and Al-Ti-O(1.16×10^(-17)to 3.77×10^(-16)N).
基金the Association SSF Strategic Mobility Grant(No.SM22-0039)theÅForsk Foundation(No.23-540)for supporting the research regarding inclusion engineering.
文摘High-temperature confocal scanning laser microscopy(HT-CSLM)is a potent methodology for investigating various phenomena in the field of metallurgy.Initially applied to the observation of solid phase transformations and solidification,this method has gained traction in the field of non-metallic inclusion in steels in recent years.An overview of the experimental capabilities of HT-CSLM and the most important results of recent investigations regarding the topics of clean steel production are provided.It includes the formation of intragranular acicular ferrite(IAF)from the surface of non-metallic inclusions during the continuous cooling and heat treatment,which can be especially beneficial in the toughness of heat-affected zones of welded pieces.Furthermore,the investigation of agglomeration mechanisms of non-metallic inclusions(NMIs)in liquid steel is discussed to improve the insight into attraction forces between particles and clogging phenomena during continuous casting.Also,the dissolution of NMIs in various steelmaking slags can be observed by HT-CSLM to compare dissolution rates and mechanisms of NMI,where significant influences of temperature and chemical composition of the slag were shown.Last but not least,the experimental work regarding the interface between steel and slag is discussed,where novel techniques are currently being developed.A comprehensive summary of experimental techniques using HT-CSLM equipment to investigate different interactions of NMIs with steel and slag phases is compiled.
基金financially supported by the National Key R&D Program,China(No.2023YFB3709900)the National Nature Science Foundation of China(No.U22A20171)+1 种基金China Baowu Low Carbon Metallurgy Innovation Foudation(No.BWLCF202315)Hebei Steel Group’s Key Science and Technology Program,China(No.HG2022103)。
文摘The instantaneous morphological transition of triangular Al_(2)O_(3) particles with various sizes in the molten Ca-treated steel was observed using a confocal scanning laser microscope at the steelmaking temperature.The composition of inclusions at different times was analyzed using scanning electron microscopy-energy dispersive spectroscopy.The shape evolution of particles was characterized by the shape parameter of overall regularity.It was found that the overall regularity of particles gradually increased with time during the calcium treatment.The geometry of particles tended to be more rounded and regular as the overall regularity increased during the modification process.An empirical formula was proposed to predict the composition of inclusion particles based on their overall regularity during the calcium treatment.When the CaO/Al_(2)O_(3) mass ratio in the particle increased to 0.451,the particle was considered an ideal spherical calcium aluminate inclusion with the overall regularity of 1.Smaller particle sizes promoted the transformation of Al_(2)O_(3) inclusions to spherical calcium aluminates during the calcium treatment.
基金supported by the Natural Sciences and Engineering Research Council of Canada(No.RGPIN-2023-03227 Schiavo)。
文摘We present the design of two interacting harmonic non-elliptical compressible liquid inclusions embedded in an infinite isotropic elastic matrix subjected to uniform remote in-plane stresses.The original constant mean stress(or the first invariant of the stress tensor)in the matrix remains undisturbed in the presence of the two harmonic liquid inclusions.The two non-elliptical liquid-solid interfaces are described by a fourparameter conformal mapping function that maps the doubly connected domain occupied by the matrix onto an annulus in the image plane.The closed-form expressions for the internal uniform hydrostatic stress fields within the two liquid inclusions are obtained.The hoop stresses are uniformly distributed along the two liquid-solid interfaces on the matrix side.
基金the Natural Sciences and Engineering Research Council of Canada(NSERC)for funding this researchThis research used a high temperature confocal laser scanning microscope-VL2000DX-SVF17SP funded by Canada Foundation for Innovation John Evans Leaders Fund(CFI JELF,Project Number:32826),a PANalytical X’Pert diffraction instrument located at the Centre for crystal growth,Brockhouse Institute for Materials Research,and a scanning electron microscope-JEOL 6610 located at the Canadian Centre for Electron Microscopy at McMaster University.W.Mu would like to acknowledge Swedish Iron and Steel Research Office(Jernkonteret),STINT and SSF for supporting the time for international collaboration research regarding clean steel.
文摘Dissolution kinetics of CaO·2Al_(2)O_(3)(CA_(2))particles in a synthetic CaO-Al_(2)O_(3)-SiO_(2)steelmaking slag system have been investigated using the high-temperature confocal laser scanning microscope.Effects of temperature(i.e.,1500,1550,and 1600℃)and slag composition on the dissolution time of CA_(2)particles are investigated,along with the time dependency of the projection area of the particle during the dissolution process.It is found that the dissolution rate was enhanced by either an increase in temperature or a decrease in slag viscosity.Moreover,a higher ratio of CaO/Al_(2)O_(3)(C/A)leads to an increased dissolution rate of CA_(2)particle at 1600℃.Thermodynamic calculations suggested the dissolution product,i.e.,melilite,formed on the surface of the CA_(2)particle during dissolution in slag with a C/A ratio of 3.8 at 1550℃.Scanning electron microscopy equipped with energy dispersive X-ray spectrometry analysis of as-quenched samples confirmed the dissolution path of CA_(2)particles in slags with C/A ratios of 1.8 and 3.8 as well as the melilite formed on the surface of CA_(2)particle.The formation of this layer during the dissolution process was identified as a hindrance,impeding the dissolution of CA_(2)particle.A valuable reference for designing or/and choosing the composition of top slag for clean steel production is provided,especially using calcium treatment during the secondary refining process.
基金supported by the National Natural Science Foundation of China-Liaoning Joint Fund (U1908224)。
文摘The quality of stainless steel is closely related to the deformability of inclusions,which is significantly affected by their compositions.The present study first inve stigated the evolution of inclusion compositions in AI-killed steel with rare earth-alkali metals(Ca or Mg)combined treatme nt through four laboratory-scale experiments.The Ce contents in the final steel are 0.0080 wt%,0.015 wt%,0.016 wt%and 0.010 wt%,respectively.The Mg content is 0.0014 wt%in Ce-Mg combined treated steel,and the Ca content is0.0015 wt%in Ce-Ca combined treated steel.The deformability of inclusions in both Ce_(2)O_(3)-Al_(2)O_(3)-CaO and Ce_(2)O_(3)-Al_(2)O_(3)-MgO systems was subsequently evaluated by calculating their Young's modulus at low temperature.The results show that irregular Al_(2)O_(3)and MgAl_(2)O_(4)with poor deformability are modified to CeAlO_(3)and Ce_(2)O_(3)by Ce treatment,resulting in the decrease of Young's modulus of inclusions.The deformability of inclusions is further improved due to the transformation from lumped-like CeAlO_(3)to spherical CaO-Al_(2)O_(3)-Ce_(2)O_(3)caused by Ca treatment,and some of these inclusions are the ones with low liquidus temperature.Thermodynamic analysis was used to discuss the control condition of the formation and evolution of inclusions.Accordingly,the appropriate addition amounts of Al,Mg,Ce,and Ca are expected to control inclusion compositions and properties,including deformability and liquidus temperature,thereby improving the steel performance.
文摘The transformation of inclusions was studied when control technology of refining top slag in ladle furnace was used in X80 pipeline steelmaking.Sufficient amount of aluminum was added to experimental heats for final deoxidation during BOF tapping,and then the refining top slag with high basicity and strong reducibility was adopted to transform Al 2 O 3 to inclusions with low melting point.The results show that the composition of inclusions changes in order of "Al 2 O 3 → MgO-Al 2 O 3 system→ CaO-MgO-Al 2 O 3 system→ CaO-Al 2 O 3 system".And the inclusions after LF refining are liquid or semi-liquid state at the temperature of steelmaking,which are easily removable to obtain high cleanliness steel by collision,agglomeration and flotation.
