Chemical Composition Of Inclusions Research Articles

Regional characteristics of iron manufacturing techniques and the related issue of the supply system on Han’s southern Frontiers: A metallurgical study of iron implements from Chenzhou, Hunan

Southern Hunan is known to be one of the few iron manufacturing regions in the Han period. The study of iron implements from this region should yield important evidence concerning the regional iron-making techniques used and the local iron industry. We provide a detailed account of the technological aspects of iron implements yielded from Chenzhou, a major node on the traffic routes entering the broader southern frontiers. Our analysis focuses on the metallographic features and chemical compositions of inclusions in the examined objects. The results reveal that cast iron and related annealing or decarburization techniques were commonly used. Most implements were made using solid-state decarburization of cast iron, along with malleable cast iron and fined iron. This technological profile is similar to other case studies in the literature, but also highlights regional characteristics such as the relatively sparse presence of fined iron. Based on this observation, we discuss various factors that could have contributed to this situation. In a broader context, the analysis of this collection can contribute to the further investigation of the regional characteristics of the Han period iron industry.

Effect of Ruhrstahl Heraeus Refining Time on Inclusions and Rolling Contact Fatigue Life of a High‐Carbon Chromium Bearing Steel

According to the variation in the average composition, the average size, the number density, and the area fraction of large‐size inclusions during Ruhrstahl Heraeus (RH) refining process, large‐size inclusions in the high‐carbon chromium‐bearing steel reach the lowest level when the vacuum cycle time is 25 min. When the soft blowing time reaches over 25 min, the number density and area fraction of large‐size inclusions increase. The rolling contact fatigue (RCF) life of the forged steel samples is measured using a thrust RCF tester, indicating that the fatigue life of no. 1 steel (vacuum cycle 40 min, soft blowing 20 min) is 12% higher than that of no. 2 steel (vacuum cycle 20 min, soft blowing 40 min). Based on the estimation of the characteristic size of inclusions in the forged steel by the statistics of extreme values (SEV) method, it is concluded that when the characteristic size and the chemical composition of inclusions in steels are similar, the RCF life is increased by 12% when the number density of large‐size inclusions decreases from 0.63 to 0.44 mm−2.

Inclusions in ice layers formed by melting and refreezing processes in a Greenland ice core

AbstractIn recent decades, surface melting on the inland Greenland ice sheet has increased, leading to significant meltwater-refreezing in the snow and firn. Increased knowledge of the physical and chemical characteristics of these melt features (i.e., ice layers) is needed to help estimate future global sea-level rise. Here, using a combination of microscopy and spectroscopy, we investigate the size, shape, location, and chemical compositions of inclusions in 12 ice layers of the SIGMA-A ice core in the northwestern Greenland ice sheet (78°03′06″N, 67°37′42″W, 1490 m a.s.l.). In the ice layers, we found inclusions exceeding 30 μm diameter that could only be formed by melting–refreezing, which we classify into columnar-, particle-, and rod-like inclusions. We propose that the smaller columnar- and particle-like inclusions of solid Na2SO4⋅10H2O and CaSO4⋅2H2O form first, within the ice grains, followed by the larger rod-like inclusions of brines with mainly Na+and Cl−in grain boundaries. Our results suggest a new proxy that may help identify past warm climates in deeper ice cores in Greenland and for studying future ice sheet melting behavior.

Ultrapotassic Aluminosilicate Melts: Specifics of Formation by the Example of Synnyrites from the Synnyr Massif

Abstract —To reveal the formation conditions of synnyrites in the Synnyr alkaline pluton, we studied melt inclusions in the minerals of shonkinites and pseudoleucite syenites, in apatite segregations in pyroxenites, shonkinites, and synnyrites, and in the minerals of later monchiquite–camptonite dikes. Based on the obtained and earlier published data, a conclusion has been drawn that all plutonic rocks of the massif formed from the same parental alkali-basaltic magma during long-term crystallization differentiation and fractionation in a closed system excluding a release of volatile components. Similar minerals in the rocks crystallized at similar temperatures in the same sequence: clinopyroxene (1280–1150 °C) → leucite (1250–1200 °C) → K-feldspar (1200–1180 °C) → apatite (above 1180–1050 °C) → nepheline and kalsilite. The composition of the parental magma during crystallization evolved toward an increase in Si, Al, and K contents and a decrease in Fe, Mg, and Ca contents, i.e., toward melaphonolite and phonolite melts. The differentiation and fractionation processes led to the separation of minerals according to their specific gravity: Heavy minerals (clinopyroxene, ore minerals, and apatite) descended to the bottom of the magma chamber, forming the lower melanocratic series, and light minerals (leucite, K-feldspar, and foids), together with the residual melt, accumulated in the upper horizons of the chamber, forming the upper leucocratic series of rocks. During crystallization, the amount of fluids increased. At 920–830 °C, the fluids contained 3033–4051 mg/kg CO2, 397–644 mg/kg H2O, and 42.7–83.7 mg/kg CO. At the early high-temperature stage, when the amount of fluids was insignificant, the trend of magma transformation coincided with the trend of basaltoid crystallization. This fact is evidenced by the homogenization temperatures and chemical composition of inclusions in the minerals of monchiquite–camptonites and alkali basaltoids, similar to those in the plutonic rocks of the massif. Clinopyroxene crystallized in dike rocks at 4.58 kbar at a depth of 10–12 km. At the stage of crystallization of feldspars, when the amount of fluids in melts significantly increased during the formation of plutonic rocks and drastically decreased during the formation of basaltoids, the formation trends of these rocks became different. The trend of basaltoid crystallization was directed toward trachyte melts with an increase in Si contents and a decrease in Fe, Mg, Al, and alkali contents. During the formation of plutonic rocks of the massif, the high water pressure prevented the formation of plagioclase, and the melts became more enriched in Al and K and acquired a high-alumina ultrapotassic composition, forming kalsilite–nepheline–K-feldspar synnyrites at the final stages of transformation. A conclusion has been drawn that synnyrites crystallized from the residual products of differentiation and fractionation of alkali-basaltic magma in the temperature range slightly above 1050–1180 °C in a closed system excluding a release of volatiles. The occasional occurrence of synnyrites is due to the limited natural occurrence of closed magma chambers, macroanalogs of inclusions of mineral-forming media in minerals.

Composition of Organosilicate Coatings High-Temperature Breakdown Products and Their Distribution in the Weld

The construction assembly and the repair of steel constructions painted with protective coatings are often carried out using arc welding. During the welding process, the coating in the weld zone is degrading. The protective coatings breakdown products are involved in the pore and non-metallic inclusion formation in the weld, the composition and distribution study of which makes it possible to analyze the reactions occurring during the welding. In this study, welding beads were deposited on the coated sheet surface by MAG welding. The distribution of inclusions (the average diameter and the relative content) along with the porosity in different bead zones were investigated by optical and scanning electron microscopy and digital image processing, and the chemical composition of inclusions was determined using energy-dispersive X-ray spectroscopy. The amount of diffusible hydrogen in the deposited metal was estimated with the vacuum method. In this work, four organosilicate coatings grades, differing in their purpose and heat resistance, were used, and their effect on the weld was studied.

Investigation of Inclusion Agglomeration and Flotation During Levitation Melting of Ni-Based Superalloy in a Cold Crucible

Inclusion agglomeration and flotation during levitation melting in a cold crucible were investigated. The morphology, number and chemical composition of inclusions were characterized by scanning electron microscopy and transmission electron microscopy with energy-dispersive x-ray spectroscopy analysis. In the billet, inclusions were mainly single mixed inclusions (oxide as the core, nitride as the shell), and their size was in the range of 1–7 μm. After levitation melting, approximately 81% of inclusions existed in the form of clusters. The number of clusters was higher at the top, and the size was larger at the top (150–250 μm). The mechanism of levitation melting removing inclusions was discussed by collision theory. First, nitrides dissolved, and the core oxides were exposed. Then, oxides collided, agglomerated, and floated. Turbulent collision played the leading role in inclusion agglomeration, while Stokes collision was predominant for inclusion flotation. Finally, nitrides precipitated again during solidification.

Characterization of impurities present on Tihimatine (Hoggar) quartz, Algeria

Many of today's advanced materials depend on quartz as a raw material.Quartz usually contains abundant inclusions, both solid and liquid, and due to the number of these inclusions and their small size, complete separation is most difficult.Typical properties of raw quartz that must be characterized are: Size and Chemical composition of inclusions, their spatial distribution, localization of isomorphic substitutional elements (e.g. Al, Fe).The aim of this study has been to test experimental methods for investigating some inclusions (impurities) present in the Tihimatine quartz from El Hoggar region deposits (southern Algeria) using X Ray Fluorescence, scanning electron microscopy, optical Microscopy with reflected and transmitted lights, infra-red spectrometer, Raman spectrometer.Despite the high concentration of SiO2 in studied quartz reaching 98%, several harmful inclusions were found and identified as hematite, anatase, muscovite, graphite, it contains: Fe, Ti, Al, K, Ca. Some fluid inclusions were found. We detect the presence of carbon dioxide and water using raman spectroscopy.The repartition of solid impurities is aleatory and not homogeneous with maximum size of 10 μm.Concerning the fluid impurities, their diameter vary between 5 and 20 μm and their repartition is aleatory.

Comparison of 2D and 3D morphology of non-metallic inclusions in steel using different methods

In the current work, the two-dimensional (2D) morphology of MnS inclusions with different shapes, including spherical, rod-like, flower-like, polyhedron and aggregated cluster, as well as spherical oxides were observed. The three-dimensional (3D) morphology of inclusions extracted from steel using acid dissolution, but the MnS was reacted away with acid during the extraction of the inclusion from the steel matrix. It is shown that the 2D method is hardly accurate to detect the morphology and size of inclusions comparison 3D morphology of inclusions. Therefore, a method of separation, extraction and analysis of non-metallic inclusions in steel was presented. Electrolytic extraction using non-aqueous electrolytes were performed to dissolve the conductive steel matrix and remain nondestructive inclusions. Scanning electron microscopy (SEM) with an energy-dispersive spectrometer (EDS) was used to obtain the integrated 3D morphology, size and chemical composition of inclusions. The morphology of MnS inclusions was reclassified on the basis of the integrated 3D morphology under the following categories: elliptical, spherical, rod-like, plate-like, irregular or polyhedron, dendrite and patch MnS precipitated on the surface of oxides. Non-aqueous electrolysis extraction with the advantage of nondestructive to inclusions, low cost, and high efficiency, and the subsequent analysis of morphology, size and chemical composition is more reliable and accurate than the traditional method. What is more, it allows a better understanding of the origin and formation of inclusions, which is helpful for the control and removed of inclusions in steels.

Characterization of the Three-Dimensional Morphology and Formation Mechanism of Inclusions in Linepipe Steels

The characterization of the three-dimensional (3D) morphology and modification of inclusions in linepipe steel plates were investigated in the present work. The deoxidation products, Al2O3 inclusions, were modified into deformable calcium aluminate inclusions by calcium treatment in order to efficiently prevent nozzle clogging. The effect of sulfur content on the morphological characteristics and chemical composition of inclusions by calcium treatment were analyzed by extracting inclusions from steel matrix using non-aqueous electrolyte and automatic scanning electron microscopy connects with energy-dispersive spectrometer. The evaluation of the effect of calcium treatment was proposed using the 3D morphology of inclusions. Meanwhile, the modification and control of inclusions in the linepipe steel were studied by thermodynamic calculation on calcium treatment with the strategy of reducing the size of inclusions before calcium treatment, and controlling the contents of [Al], [Ca], and total oxygen in a reasonable narrow range during calcium treatment. The modification and transformation process of alumina inclusions was revealed as Al2O3 → MgO-Al2O3 → CaO-MgO-Al2O3-CaS (after calcium treatment) → CaO-Al2O3-CaS. A kind of high-melting MgO-Al2O3 core was wrapped by the low-melting component of CaO-Al2O3 indicating an incomplete reduction of MgO and Al2O3 by calcium.

Inclusions modification in heat resistant steel containing rare earth elements

Based on the thermodynamic assessment of inclusions evolution, the modification experiments of inclusions containing rare earths were carried out in the Si–Mo furnace from 1600°C to 1500°C. The pure Si and Si–Al alloy were chosen as deoxidants under low and high initial oxygen content, respectively. The field emission scanning electron microscope (FE-SEM) and energy dispersive spectrometer (EDS) were employed to analyse the morphology and chemical compositions of inclusions in the samples. The spherical liquid Ce–Si–Al–O (Ce4Si5Al5O23.5) inclusions were observed in the steel, which was deoxidised by Si–Al alloy. The evolution mechanisms of inclusions were comprehensively discussed, and models for the formation of oxide inclusions were set up.

Evaluation of Steel Cleanliness in a Steel Deoxidized Using Al

The effect of magnesium in the aluminum used as a deoxidizer on the cleanliness of steel was studied throughout a steelmaking route for the production of thin slabs. Two deoxidizers with different Mg contents were used. The Mg content of a “typical” deoxidizer was ~0.5 wt pct Mg, whereas that for an alternative deoxidizer was ~2 wt pct Mg. The inclusion population at different stages of the steelmaking process was characterized in terms of chemical composition, number, and size distribution. The inclusion modification path shows that the solid Al2O3 and Al2O3-MgO inclusions formed in the early stage of the steel ladle treatment are modified into Al2O3-MgO-CaO liquid and MgO-Al2O3-liquid inclusions. Although some slight differences were observed in the ladle furnace samples, the chemical composition of inclusions was similar in the samples taken at the mold of the continuous casting, regardless of the deoxidizer used. Gumbel, generalized extreme value (GEV), and generalized Pareto (GP) distributions were used for the description of the size distribution. The GEV and GP distributions resulted in proper distributions to describe the evolution of size distribution throughout the steelmaking process. Furthermore, no statistically significant differences between inclusion size distributions resulting from the use of either deoxidizer were found.

Contribution to Deoxidation of Austenitic Steels in a Vacuum Induction Furnace with Carbon

Abstract Deoxidation of steel with carbon under reduced pressure is often used for increasing the steel purity. Suitable units for this purpose in foundries are vacuum induction furnaces. Possibilities of increasing the steel purity by deoxidation with carbon in the vacuum induction furnace were studied for the steel for the petrochemistry of specific composition 25Cr/35Ni. The charge composed of the return material only was melted in the air. During melting the charge oxidized and the oxidizing slag formed. Chemical composition of steel, morphology, chemical composition of inclusions in the steel and chemical composition of slag after vacuuming were studied on the basis of samples taken before and after vacuuming. Temperature and oxygen activity were measured before and after vacuuming. Globular inclusions with dominant content of silicon and manganese were observed in steel before and after vacuuming. Contents of total oxygen in steel didn’t change significantly during vacuuming. On the basis of composition of inclusions and measured oxygen activity the activity of Cr2O3 in inclusions was calculated. A slag sample was taken after vacuuming and equilibrium oxygen activity in steel with regard to the Cr2O3 content in the slag was estimated from the slag composition. Equilibrium oxygen activity in relation to the Cr2O3 content in the slag was higher than equilibrium activity measured in the steel. For this reason it is not possible, under the studied conditions, to decrease oxygen content in steel during vacuuming.

Effect of Inclusions’ Behavior on the Microstructure in Al-Ti Deoxidized and Magnesium-Treated Steel with Different Aluminum Contents

To clarify the precipitation behavior of beneficial inclusions and mechanism of their effects on microstructure, the effect of aluminum content on inclusion’s characteristics and their influence on the refinement of microstructure in Al-Ti complex deoxidized magnesium-treated steels were systematically investigated based on experiment and calculation. The results showed that due to the dual effects of Ti and Mg deoxidation, a large amount of finely dispersed Al2O3-TiO x -MgO inclusions in low aluminum steel with a complex multilayer or mosaic structure were formed, whereas a relatively smaller amount of Al2O3-MgO inclusions with the simple bundle structure were observed in high aluminum steel. The Al2O3-TiO x -MgO core oxides are more conducive to the precipitation of multiple manganese sulfides with thinner thickness on their local surfaces. Thus, the inclusion deformation, which mainly depends on the surface manganese sulfides layer, is smaller in low aluminum steel than that in high aluminum steel. Complex inclusions in low aluminum steel can pin austenite grain boundaries and induce interlocking acicular ferrite effectively. In addition to the small size and chemical composition of inclusions, the complex structure of oxides and the precipitation of multiple MnS on their surface are important to the nucleation of interlocking AFs on inclusions in Ti-deoxidized Mg-treated steel. The AFs quantity is much more, and the grain size is more uniform in low aluminum steel than that in high aluminum steel.

Formation of Low-Melting-Point Inclusions in Al-Deoxidized Steel Refined by High-Basicity Calcium Aluminate Slag in ZrO2 Crucible Experiments

ZrO2 crucible experiments were carried out in the laboratory to study the formation of low-melting-point inclusions in steel, during which aluminum deoxidization and a high-basicity calcium aluminate refining slag (CaO/SiO2: 6 to 8, Al2O3 40 to 45 pct) were used. Four experiments were done with different slag/steel reaction times (30, 60, 90, and 180 minutes). It was found that inclusions were mainly composed of CaO-Al2O3-ZrO2 with very limited SiO2, in spherical morphology and with sizes mainly less than 5 μm. They can be classified into two types according to the ZrO2 content. The first type contained much lower ZrO2, whereas a much higher level of ZrO2 was detected in the other type. An evolution of inclusions with the reaction time was observed and studied. The obtained results indicated that chemical compositions of inclusions were widely scattered in the CaO-Al2O3-ZrO2 phase diagram after 30 min reaction. However, the composition of inclusions became much more uniform and concentrated in low-melting-temperature regions at 60, 90, and 180 minutes, which would be favorable to prevent nozzle clogging and fatigue problems. Compared with the authors’ previous results obtained in MgO crucible experiments, it was found that low-melting-temperature inclusions can be targeted in shorter time in ZrO2 crucible experiments, without any degradation of cleanliness.

Thermodynamic behavior and morphology of impurities in metallurgical grade silicon in process of O2 blowing

Gas blowing is a valid method to remove the impurities from metallurgical grade silicon (MG-Si) melt. The thermodynamic behavior of impurities Fe, Al, Ca, Ti, Cu, C, B and P in MG-Si was studied in the process of O2 blowing. The removal efficiencies of impurities in MG-Si were investigated using O2 blowing in ladle. It is found that the removal efficiencies are higher than 90% for Ca and Al and nearly 50% for B and Ti. The morphology of inclusions was analyzed and the phases Al3Ni, NiSi2 and Al3Ni were confirmed in MG-Si by X-ray diffraction. It was found that SiB4 exists in Si–B binary system. The chemical composition of inclusions in MG-Si before and after refining was analyzed by SEM-EDS. It is found that the amount of white inclusion reduces for the removal of most Al and Ca in the forms of molten slag inclusion and the contents of Fe, Ni and Mn in inclusion increase for their inertia in silicon melt with O2 blowing.

Study of rolling contact fatigue of bearing steels in relation to various oxide inclusions

Flaking failure of rolling contact fatigue is known to originate from non-metallic inclusions, where fatigue cracks occur at subsurface region of materials. It is fundamental to understand the main factors governing the rolling contact fatigue life. Steel samples with different size and chemical composition of oxide inclusions were evaluated on rolling contact fatigue life. As a result, (i) Rolling contact fatigue life was improved by reducing the oxide size. (ii) Rolling contact fatigue life varied depending on the oxides composition. It has been concluded that the chemical composition of the inclusions is an important factor of the rolling contact fatigue life, in addition to the inclusion size.

Metamorphic evolution of the archean eclogite-like rocks of the Shirokaya and Uzkaya Salma area (Kola Peninsula): Geochemical features of zircon, composition of inclusions, and age

Zircon from the eclogite-like rocks of the Shirokaya and Uzkaya Salma area (Kola Peninsula) was studied using a complex of mineralogical and geochemical methods (CL, BSE, microprobe, and REE distribution). Different zones distinguished within zircon crystals were dated on a SHRIMP-II mass spectrometer. Mineral and chemical compositions of inclusions in the zircons were analyzed. Based on these studies, the following stages of the formation and transformation of the rocks were determined: (1) formation of basic protolith of the eclogite-like rocks of the Shirokaya and Uzkaya Salma area 2.94–2.93 Ga ago; (2) the granulite-facies metamorphism of the eclogite-like rocks of the Shirokaya Salma 2.72 Ga ago; (3) the onset of decompressional cooling with formation of Cpx-Pl symplectites at 2.70 Ga ago; and (4) final metamorphic reworking together with surrounding TTG under the amphibolite-facies conditions at 1.89 Ga ago. The studied rocks and minerals revealed no isotope-geochemical or geochronological signs of eclogite metamorphism. Geochemistry of the primary magmatic zircons showed that the protolith of eclogite-like rocks was gabbro rather than MOR basalts. The formation of garnet in the rocks of the Uzkaya and Shirokaya Salma area is dated at 2.70 and 1.89 Ga ago, which is consistent with petrological observations of later formation of garnet relative to omphacite. Obtained data led us to prefer a magmatogenic model, which suggests that omphacite in the rocks of the Shirokaya and Uzkaya Salma was presumably formed during crystallization from basic melt, rather than during eclogite-facies metamorphism.

Inclusion Characteristics of Bearing Steel in a Runner after Ingot Casting

AbstractIn the uphill teaming method of ingot casting molten metal from the ladle goes into the runner system, which feeds one or several ingot moulds. This method is still important for production of bearing steel. In order to make clean steel, which has a controlled amount of inclusions, good understanding of inclusions characteristics is necessary. In this work non‐metallic inclusions of steel left in the runner part of an ingot casting system were studied. Inclusion type, size, and morphology were the main focus of this study. A scanning electron microscope (SEM) was used to assess inclusion size and morphology. The chemical composition of inclusions was determined by SEM equipped with EDS. An automated program called ‘INCAFeature’ was used to collect statistics of inclusion characteristics. Based on the statistical analysis of inclusion composition, four types of inclusions including oxides, sulfides, carbonitrides and complex inclusions were defined. The inclusion characteristics in the runner were also compared to literature data of inclusions found in ladle and mould samples.

Change of Inclusion Characteristics during Vacuum Degassing of Tool Steel

The inclusion characteristics were studied during vacuum degassing by interrupting the operation at five different times after the start of operation. Slag and steel samples were collected and thereafter assessed with respect to steel and slag composition, total oxygen content, size distribution of inclusions and chemical composition of inclusions. The main conclusion is that the number of inclusions in the different size classes as well as the total oxygen content seem to reach a minimum value after around ten minutes of vacuum degassing. Furthermore, it seems to be a consistent trend that, during vacuum degassing, the top slag influences the inclusion composition.

High-speed scanning laser-induced breakdown spectroscopy at 1000 Hz with single pulse evaluation for the detection of inclusions in steel

Spatially resolved information about the distribution and chemical composition of inclusions in steel are gained by scanning methods, such as scanning electron microscopy with energy dispersive X-ray spectroscopy, electron probe microanalysis or capillary-X-ray flourescence. Scanning laser-induced breakdown spectroscopy (LIBS) offers distinct advantages in contrast to these conventional methods. Sample polishing or high vacuum conditions are not necessary, a simple grinding of the sample is sufficient for the preparation. Analysing times can be reduced significantly. At Fraunhofer ILT a measuring system was developed enabling for the first time high-speed scanning LIBS with measuring frequencies of up to 1000 Hz. Sample surfaces with dimensions up to 110×45 mm2 can be analyzed. Light elements such as C, N, O, P, and S are detected, which is demonstrated by the identification of nonmetallic inclusions in steel. Principle, features and results of high-speed scanning LIBS with a spatial resolution<20 μm are presented.