Main Inclusions Research Articles

Effect of Cerium on the Behavior of Inclusions in H13 Steel

The modification mechanism of cerium (Ce) on oxides and multilayer carbontrides in H13 steel is investigated by industrial trials and thermodynamic calculations. The morphology, composition, and size of inclusions are analyzed by scanning electron microscopy and energy dispersive spectroscopy. The main inclusions in H13 steel without Ce content in the molten steel are MgAl2O4 spinel inclusions and multilayer carbonitrides. The carbonitrides have a multilayer structure in which MgAl2O4 acts as the nucleation core and the second layer is (Ti, V)(C, N). As the cerium content in molten steel increases from 0 to 0.03 wt%, the MgAl2O4 is effectively modified into cerium oxide (Ce–O) and cerium oxy‐sulfide (Ce–O–S), and the evolutionary process is as follows: MgAl2O4 → CeAlO3 → Ce–O and Ce–O–S. Likewise, the structure of multilayer carbonitrides in the H13 steel also changed. The MgAl2O4 and CeAlO3 act as heterogeneous nucleation cores of multilayer carbonitrides. However, Ce–O and Ce–O–S can effectively inhibit the heterogeneous nucleation of carbonitrides. The number density of large‐size carbontrides is remarkably reduced with increasing Ce content. A prediction model of optimum Ce content in molten steel is built, which has remarkable agreement with the experimental observations.

Effect of Oxides on Characteristics of MnS and Transverse Mechanical Properties in Commercial Al-Killed Non-Quenched and Tempered Steel

In this paper, the characteristics of tensile fractures and the typical inclusions in as-cast blooms and as-rolled bars are carefully investigated to figure out the causes of different transverse tensile properties in two commercial non-quenched and tempered steels. In low Ca bearing steel (3 ppm), MgO–Al2O3 (MA) + MnS are main inclusions and MA oxides express high ability for MnS heterogeneous nucleation. Consequently, the MnS inclusions in as-rolled bars are larger in size and smaller in number, the transverse ductility is satisfied due to the high space distance between the MnS inclusions. However, the transverse ductility of high Ca bearing steel (9 ppm) is much poor because MnS inclusions are agminated in distribution, causing severe stress concentration. The calculation results show that CaO in CaO–MgO–Al2O3 oxides (CMA) would react with Al and S in molten steels, suppressing the formation of MnS inclusions on surface of CMA oxides. An integrated illumination including the evolution processes of typical oxides in molten steels, the generation behaviors of MnS during the solidification, the deformation behaviors of sulfides and the relationship between sulfides and crack initiation have been conducted based on observation results and thermodynamic calculation.

Inclusion Measurement and Identification in Mg-Based Alloys: Application of the Brightimeter Technique

The present investigations were carried out on experimentally prepared AM50A and AZ91D alloys. The main thrust was the application of the Brightimeter technique in quantifying the concentration of the inclusions in these alloys. The results show that the Brightimeter indices are low when the amount of oxides, i.e., MgO, Al2O3, Al2MgO4 is high. Reducing the oxide concentration increases the Brightimeter readings (indices). It is concluded that the Brightimeter apparatus is an effective technique in determining the metal cleanliness in terms of detecting and measuring the inclusion content. Its sensitivity increases with the increase in the amount of inclusions. At low levels of inclusion concentration, there is a noticeable fluctuation in readings of the Brightimeter. The main parameter to be considered is the melting and solidification process. It is recommended that the Brightimeter readings (indices) should be coupled with metallographic examination. The main inclusions are magnesium oxides (MgO), magnesium hydroxides (Mg(OH)x), aluminum oxides (Al2O3), spinel (a mixture of MgO + Al2O3). In some cases, pure metals such as iron (Fe) and aluminum (Al) were also observed along with their oxides, i.e., FeO and Fe2O3. The use of flux as a protective agent may cause the presence of other types of inclusions such as K, Na and Ca. The quantity of oxides depends to a large extent on the inclusions initially present in the as-received alloy. Recycled alloys were found to contain the maximum amount of inclusions.

Effects of Non-metallic Inclusions on Hot Ductility of High Manganese TWIP Steels Containing Different Aluminum Contents

The characteristics of inclusions in Fe-16Mn-xAl-0.6C (x = 0.002, 0.033, 0.54, 2.10 mass pct) steels have been investigated and their effects on hot ductility of the high manganese TWIP steels have been discussed. Ductility is very poor in the steel containing 0.54 mass pct aluminum, which is lower than 20 pct in the temperature range of 873 K to 1473 K (600 °C to 1200 °C). For the steels containing 0.002 and 2.10 mass pct aluminum, ductility is higher than 40 pct in the same temperature range. The hot ductility of steel containing 0.033 mass pct aluminum is higher than 30 pct throughout the temperature range under examination. With increasing aluminum content, the main inclusions in the steels change along the route of MnO/(MnO + MnS) → MnS/(Al2O3 + MnS) → AlN/(Al2O3 + MnS)/(MgAl2O4 + MnS) → AlN. The thermodynamic results of inclusion types calculated with FactSage software are in agreement with the experimental observation results. The inclusions in the steels containing 0.002 mass pct aluminum do not deteriorate the hot ductility. MnS inclusions whose average size, number density, and volume ratio are 1.12 μm, 15.62 mm−2, and 2.51 × 10−6 in the steel containing 0.033 mass pct aluminum reduce the ductility. In the steel containing 0.54 mass pct aluminum, AlN inclusions whose average size, number density, and volume ratio are 0.878 μm, 16.28 mm−2 and 2.82 × 10−6 can precipitate at the austenite grain boundaries, prevent dynamic recrystallization and deteriorate the hot ductility. On the contrary, in the steel containing 2.10 mass pct aluminum, the average size, number density and volume ratio of AlN inclusions change to 2.418 μm, 35.95 mm−2, and 2.55 × 10−5. They precipitate in the matrix, which do not inhibit dynamic recrystallization and thereby do not lead to poor hot ductility.

A Comparative Study of Pottery from Mersin-Yumuktepe and Arslantepe, Turkey

The purpose of this paper is to present a summary of the application of non-destructive techniques used in a comparative study of eighty pottery fragments of the Chalcolithic period (5000 BC ca.) and Late Bronze Age (1650 - 1200 BC ca.), found in Mersin-Yumuktepe (Southern Turkey) and Arslantepe (Malatya, Eastern Turkey). The use of a scanning electron microscopy, equipped with a system of energy dispersive X-ray spectroscopy (SEM-EDX), has allowed determining their morphology, the main inclusions and the elemental composition of ceramic mixtures of each artifact. Moreover, the determination of majority and trace elements has revealed various information, such as the origin of raw materials or the contamination that occurred in the manufacturing phase. The multivariate statistical method has allowed highlighting similarities and/or differences among the ceramics.

Growth and post-growth defects in a diamond from Finsch mine (South Africa)

A diamond from the Finsch mine (South Africa) was investigated by X-ray diffraction topography to characterize the extended defects and to reconstruct the growth history. The sample was a doubly polished triangular diamond slice with a rounded side in which re-entrant corners could be seen and the specimen exhibited anomalous birefringence. X-ray topographs show that the sample is actually a mosaic crystal that developed through aggregation of sub-individual parts during growth: some slightly rotated relative to one another and others twinned. The twin law is by reticular merohedry and consists of the well-known 2-fold rotation around [111]. Micro-Raman spectroscopy data revealed that the main inclusions are pyrope and enstatite trapped in the inner part of the individual. No dislocations nucleated from the silicate inclusions. Growth-sector boundaries, dislocations, grain boundaries and twinning indicate that these features formed during the growth of diamond. Throughout the whole sample and chiefly in the regions showing a lower density of inclusions, packed lamination lines parallel to an octahedral face can be observed. These laminations represent a polysynthetic twinning commonly observed in diamonds which have undergone plastic deformation and are considered to be a post-growth defect. The analysis of the structural defects allows a reconstruction of a complex growth history, characterized by a sequence of alternating episodes of growth and dissolution and, lastly, plastic deformation. This study represents a methodological contribution to the studies on the origin of diamond.

Evaluation of Inclusions in P/M Superalloy

The non-metallic inclusions in master alloy, P/M superalloy and HIP powder billet were studied in this paper. The results show that the amount of inclusions in master alloy is higher than that of the superalloy powers. The EB-button analysis shows that the main non-metallic inclusions in both the master alloy and the HIP powder billet is Al2O3.The amount of the inclusion in master alloy is about 0.166cm2/kg and the size of most inclusions is in the range of 100μm to 200μm, while the maximum inclusion size reaches 400μm.In the P/M superalloy billet, the content of inclusion is only 0.01cm2/kg and the size of most inclusions is less than 50 μm.

Micro-Behavior of Inclusions in X80 Pipeline Steel under Tensile Loading

Specially designed SEM in-situ tensile tests have been conducted to trace the entire process of crack initiation and propagation induced by inclusions in X80 pipeline steel. The main inclusions are complex oxides containing aluminum, calcium and magnesium with round or oval shape, and their sizes are in the range of 3~20μm. Cracks initiate firstly in inclusions and also easily initiate among inclusions if they distribute in the steel as an inclusion chain. The size of an inclusion has little effect on the initiation stress of the first crack, which mainly depends on the yield strength of the steel. Once a crack initiates in X80 pipeline steel, it zigzag propagates along the direction of maximum shear stress that orients in about 45° to the loading direction till failure. In the process of crack propagation, the crack experiences propagation, anti-crack, bluntness and new micro-cracks initiation again and again. These valuable experimental results reveal the harmful effect of inclusions in micro-scale and are helpful for understanding failure mechanisms of the advanced steel components.

Research on the Effects of the Refining Treatment to the Properties of Dual-Phase Wear-Resistant Steel

Using refining agent to proceed refining treatment on dual-phase wear-resistant steel, the refining agent is made up of CaO, CaF2, Al2O3, Al, Na2CO3 and BaCO3. The experimental furnace is 25kg vacuum induction furnace, stalling 10 minutes after adding the refining agent, the heating temperature is between 1550 and 1600°C. By doing this, the content of harmful impurities including O, N and S in the steel is significantly reduced and the mainly existing form of the main non-metallic inclusions is changed, it also reduces the size and number of the microstructure of the inclusions in the steel and improves the impact toughness and elongation of dual-phase wear-resistant steel significantly.

Effect of Refining Slag on the Inclusions of Hard Wire Steel during Melting Process

The effect of the refining slag composition on the total oxygen content and inclusions in steel was investigated in 100 t UHP Electric Furnace – LF – Billet CC process. The test steel was 77B hard wire steel and Si-Mn alloy was used as the deoxidizer. Three types slag were used in the industrial tests, which including CaO-CaF2, CaO-CaF2 adding CaC and CaO-Al2O3 refining slag. The results shown that the lowest total oxygen contents of rolled bar can be gained using the CaO-CaF2 refining slag adding CaC, which is 0.0036%, while the total oxygen contents of rolled bar using CaO-Al2O3 refining slag is higher a little than the heats using CaO-CaF2 refining slag. The CaO-SiO2 and CaO-Al2O3-SiO2 compound inclusions with the size of about 5 μm are the main inclusions in the heats refining by the CaO-CaF2 refining slag in the rolled bar, but the pure, indeformable Al2O3 inclusion can also be found with the size of about 10 μm. The CaO-Al2O3-SiO2 and Al2O3-SiO2-MnO compound inclusions are the main inclusions in the heats refining by the CaO-CaF2-CaC refining slag, but most of the inclusion shape is irregular with bigger size of about 10 μm. Similar with the heat using CaO-CaF2 refining slag, the pure Al2O3 inclusion with edge angle can be found in the rolled bar. The inclusions in the rolled bar treated by CaO-Al2O3 refining slag are CaO-Al2O3-SiO2 compound inclusions, most of which are nearly globular shape with the relative small size of about 5 μm. All of the inclusions in rolled bar lie on the low melting zone in the CaO-Al2O3-SiO2 ternary phase diagram in the heats using CaO-Al2O3 refining slag. The similar condition appeared on the most of the inclusions in the heats using CaO-CaF2 and CaO-CaF2 refining slag adding CaC, while part of which are lied on the high melting zone. Therefore, considering of the plastic deformation ability, the CaO-Al2O3 refining slag is the best slag for the melting process of hard wire steel.

Czochralski growth of Lu1‐xScxBO3:Ce solid solution crystals

AbstractSingle crystals of Lu1‐xScxBO3:Ce (x=0.2, 0.3, 0.5, 0.7) were grown by Czochralski method. Continuous solid solution with calcite structure and a linear compositional dependency of crystal lattice parameter in the system Lu1‐xScxBO3:Ce are formed and their symmetry belong to hexagonal system with R3c space group checked by X‐ray powder diffraction. The electron probe micro‐analysis measurements show that the main inclusions in Lu1‐xScxBO3:Ce crystals are in the form of Sc rich oxide and Ce rich oxide. The ICP‐AES tests show that the more Sc ion content in Lu1‐xScxBO3:Ce, the smaller effective segregation coefficient of Ce in crystal will be. The X‐ray excited luminescence spectra of Lu1‐xScxBO3:Ce crystals all present a double peaked emission band with maxima round 370 and 400 nm corresponding to Ce3+ emission and a self trapped excitons (STE) band peaking at 269 nm. In addition, due to high density, high relative light yield, fast decay time and no‐hygroscopic property, Lu0.8Sc0.2BO3:1 at%Ce crystal could be a good candidate material for scintillation application by improving the crystal quality and cerium concentration. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The Composition and Morphology Evolution of Oxide Inclusions in Ti-bearing Ultra Low-carbon Steel Melt Refined in the RH Process

Before deoxidation, the main inclusions were Fe–Mn–O inclusions in Ti-bearing ultra low-carbon steel melt. After 3 min Al addition, the inclusions changed to be granular and spherical Al2O3. Al2O3 cluster, composed of granular and spherical particles with diameter 1–2 μm, formed in 7 to 10 min after Al addition into the melt. Al2O3·TiOx inclusions with the Ti/(Al+Ti) between 0.15 and 0.30 formed 3 min after ferro-titanium addition and Al2O3·TiOx cluster formed because rich [Ti] and poor [Al] regions existed around the ferro-titanium particles and Al2O3 cluster. The Ti3O5 was hard to be formed when acid-soluble aluminum exceeded 0.035% with titanium blow 0.08%. The activity of Ti3O5 in the complex liquid phase inclusions increased remarkably with the decrease of acid-soluble aluminum and increase of titanium.

Motion behavior of non-metallic particles under high frequency magnetic field

Non-metallic particles, especially alumina, are the main inclusions in aluminum and its alloys. Numerical simulation and the corresponding experiments were carried out to study the motion behavior of alumina particles in commercial pure aluminum under high frequency magnetic field. At the meantime, multi-pipe experiment was also done to discuss the prospect of continuous elimination of non-metallic particles under high frequency magnetic field. It is shown that: 1) results of numerical simulation are in good agreement with the experimental results, which certificates the rationality of the simulation model; 2) when the intensity of high frequency magnetic field is 0.06 T, the 30 μm alumina particles in melt inner could migrate to the edge and be removed within 2 s; 3) multi-pipe elimination of alumina particles under high frequency magnetic field is also effective and has a good prospect in industrial application.

Assessment of melt cleanliness and analysis of inclusions in Al-Si alloys using the Prefil pressure filtration technique

The aluminium casting alloys A356.2 and A390.1 are two of the most popular Al-Si alloys used in automotive and die casting applications. To obtain premium quality castings, their alloy melts must possess optimum melt cleanliness, i.e., the inclusions present therein, particularly those harmful to the alloy properties, must be minimised. In recent years, melt cleanliness of aluminium alloys has been assessed by means of various filtration techniques. In the present work, the measurement of inclusions was carried out using the recently introduced pressure filtration ‘Prefil’ technique which has the advantage of providing in situ results in the form of flow rate charts. These minimise the need for time-consuming metallographic examinations for inclusion analysis demanded by other pressure filtration techniques such as PoDFA. Experiments carried out using the ‘Prefil’ technique indicate that for obtaining appropriate results, the pressure chamber and filtration crucible of the ‘Prefil’ appratus should be heated to ~300-350°C, to reduce heat loss during transfer of the liquid metal from the melt crucible to the filtration crucible. Also, the filtration temperature should be high enough to avoid possible sedimentation of inclusions in the ladle during the transfer. It was found that the main inclusions in A356.2 alloy are Al4C3, dispersed oxides, MgO and MgAl2O4, while those in A390.1 alloy are bone ash and alkaline compounds. Generation of oxide films (associated with the use of mechanical stirring to dissolve grain refiner/modifier additions to the melt) can be avoided by employing degassing instead.

Shear fracture of the main crack in the presence of rigid inclusions and an accompanying crack closure

Earlier, a paper devoted to the planar problem of the interaction between the main crack and the field of small rigid inclusions under tensile loading was published [1]. The present investigation is concerned with the problem when a similar crack-inclusions set is affected by shear loading. Attention has been paid to the analysis of the possible macrocrack edge contact. Recent investigations of macro-microcrack interaction under shear loading [2, 3] and heat flux [4, 5] have revealed that, depending on the location and orientation of the small cracks, the main crack could be partially or completely closed and the macrocrack tip stress intensity factor K I could be negative. Therefore, in order to obtain the correct stress intensity factor K I the presence of the contact zones has been taken into account. This phenomena, for the shear loading of dissimilar materials with cracks, was revealed in the 1960s and references can be found in [61. In recent years, effect of crack closure is taken into account for different investigations (see e.g. [7, 8]). The problem of interaction between the main crack and small rigid inclusions is very close to the macro-microcrack problem. So, applying the method of singular integral equations [9] and the small parameter method [10, 3], the problem of crack-microinclusions interaction under shear loading can be solved with the following assumptions: 1) one opening zone with an unknown length 2c is located within the macrocrack;

Interaction between a main crack and inclusions of a given orientation

Interaction between a main crack and inclusions of a given orientation

The chloramphenicol altered fine structure ofAnabaena cylindrica

In the presence of chloramphenicol the main peptidic inclusions of exponentially growing Anabaena cells changed from carboxysomes to cyanophycin. Prolonged chloramphenicol treatment removed both carboxysomes and cyanophycin, leaving only polyphosphate bodies. Polyphosphate bodies were common to senescent, nitrogen deficient and chloramphenicol-treated cells, but absent from exponentially growing cells. All three inclusions were present in senescent cells from aged cultures. Cyanophycin can be simply and reproducibly distinguished from osmiophilic inclusions by its strong reaction to uranyl acetate.

Comparison of the variability in a soil taxonomic unit with that of the associated soil mapping unit

The variation in morphological and chemical properties within the Westmere silt loam mapping unit mapped at the soil type level in the Wanganui district of New Zealand is compared with the variation in the same properties in the Westmere silt loam taxonomic unit. Nearly half of the measured morphological properties are similarly distributed in both the taxonomic and mapping unit, while approximately equal proportions of the remaining properties show either leptokurtic (more peaked) distributions or platykurtic (broader) distribution in the taxonomic unit. Chemical properties generally show slightly less variance (as shown by cv values) in the taxonomic unit. Considered overall, a similar degree of variation exists in both the taxonomic and mapping units. This can be explained by the main inclusions within the Westmere silt loam mapping unit being characterized by a range of morphological and chemical properties similar to the Westmere silt loam taxonomic unit and with a similar (or possible lesser) degree of variability.