Size Of Inclusions Research Articles

Multi-scale ultrasonic imaging of sub-surface concrete defects

This paper introduces a new method for creating the ultrasonic image of concrete that utilizes both linear and nonlinear wave properties in a single measurement. Linear ultrasonic imaging relies on wave velocity. The resolution of linear ultrasonics for various inclusion sizes and inclusion-to-base material ratios is numerically and experimentally studied. The nonlinear ultrasonic testing (NLUT) image is based on the acoustic nonlinearity coefficient, calculated using inputs of the first and second harmonic amplitudes, wave number, and the distance between the transmitter and receiver. The ultrasonic waveform is decomposed into its harmonics using wavelet transform. Their wave velocities, wave numbers, and amplitudes are extracted to calculate the linear wave velocity and the acoustic nonlinearity coefficient. Four calibration samples with different inclusions are tested to evaluate the effectiveness of combining two imaging methods: pure concrete, concrete with small foam inserts simulating air inclusions, and two concrete samples with larger foam inclusions. The angle dependence of acoustic nonlinearity coefficient is shown. The results show that constructing both linear and nonlinear ultrasonic imaging is necessary when the defect’s properties are unknown.

Use of recycled ceramic beads to enhance mechanical behavior of low-plastic clays

Due to the huge amount of annual non-renewable ceramic waste disposal, it is in favor of eco-system to reuse the ceramic waste in earthwork structures. Thus, among several different applications of ceramic components, they can also be used to replace aggregates in the core of embankment dams, waste disposal projects and to form subgrade of roads and railways. The main issues addressed in this study are the effect of the volumetric content and size of the ceramic inclusions on the mechanical properties of ceramic-clay mixtures. Using an experimental approach, strain-controlled monotonic, stress-controlled cyclic, and post-cyclic monotonic triaxial undrained tests were made. The innovation of this study is that sphere beads of ceramic with different diameters were added to low-plastic clay to explore the role of bead size on the mechanical properties of bead and clay mixtures under monotonic, cyclic and post-cyclic loadings. Thus, we tested four types of specimens consisting of merely pure clay, 80% clay–20% bead, 60% clay–40% bead, and 40% clay–60% bead. Scanning electron microscope (SEM) images were additionally used to investigate the fabric of the clay between the ceramic beads. Test results revealed, firstly, that effective friction angle and undrained shear strength increase with the bead content. Secondly, dilative behavior was captured in all the bead and clay mixtures. Further, both dynamic shear modulus and damping ratio increase with the bead content. Similarly, post-cyclic shear strength increases with the bead content. Finally, different bead diameters did not change the observed trend.

Modification of Al2O3 inclusions in SWRH82B steel by La/Y rare-earth element treatment

Abstract The experimental schemes of lanthanum (La) treatment, yttrium (Y) treatment, and La/Y mixed treatment of inclusions in SWRH82B steel were used. The size distribution, number density, inter-surface distance, the degree of homogeneity, and the area density of inclusions in the test steel were determined. The results show that the rare earths have a certain refinement and homogenization effect on the inclusions, and the mixed rare earths have the best effect on the inclusions in the steel. The average size of inclusions after mixed rare-earth treatment is 1.23 μm, the average size of inclusions after rare-earth La treatment is 1.79 μm, and the average size of inclusions after rare-earth Y treatment is 1.37 μm. Thermodynamic calculations show that the affinity of rare earths to oxygen in steel is higher, and the affinity to sulfur is lower. La and oxygen–sulfur have a higher affinity, and the affinity of Y and oxygen–sulfur is lower. In addition to single inclusions, there are complex inclusions in the steel.

The effect of porosity on flexoelectricity in 3D printed aluminum/polyvinylidene fluoride composites

We investigated the relationship between porosity and flexoelectricity for aluminum (Al)/polyvinylidene fluoride (PVDF) composites. Neat PVDF, composites of micron aluminum (μAl)/PVDF, and composites of nano aluminum (nAl)/PVDF were 3D printed, and the flexoelectric response was measured using a cantilever beam test setup. Voids (up to 72.4 mm3) were incorporated into the samples by decreasing the infill percent of the 3D printed material. We found that increasing the porosity via millimeter scale voids incorporated into the infill pattern decreased the average effective flexoelectric coefficient relative to the near full-density (100% infill) control samples. This contrasts with other studies that have shown increasing micron scale porosity increases the flexoelectric coefficient. In addition, we measured higher flexoelectric responses for nAl/PVDF than μAl/PVDF as well as for samples printed by the Hyrel 3D SR printer as opposed to the Ender 3 V2 printer. These results indicate that charge generation due to flexoelectricity can be altered by changing parameters such as porosity, particle size of inclusions, or manufacturing method. Smaller voids and fine particles can induce larger strain gradients than larger inhomogeneities, leading to increased flexoelectric coefficients. A competing effect is that more porosity leads to less materials, which can decrease the flexoelectric coefficient.

Uncovering the origin of critical hydrogen concentration for initiation of hydrogen-induced cracking and its relation to inclusion type and size

This paper presents a theoretical criterion and approach for determining the relationship between the critical hydrogen concentration for hydrogen-induced cracking (HIC) initiation and the type and size of non-metallic inclusions. We used plate-like MnS and sphere-like Al2O3 as representative inclusions for in-depth analyses. Our results indicate that decreasing inclusion size increases the hydrogen concentration required for HIC initiation, particularly in the range of small inclusion sizes. Al2O3 exhibits a higher susceptibility to HIC than MnS. Each type of inclusion has a specific hydrogen concentration below which crack initiation cannot begin. The critical concentration for HIC initiation in the entire steel corresponds to the lowest value among these concentrations. This study provides a quantitative and comprehensive solution to this issue.

Effect of rare earth Ce addition on inclusions in offshore engineering steel containing arsenic

The present study investigates the impact of rare earth Ce addition and holding time on inclusions in offshore engineering steel containing arsenic. The analysis was conducted using scanning electron microscopy and energy spectrum (SEM-EDS), automatic statistics of inclusions, and thermodynamic analysis. The results indicate that prior to the addition of rare earth Ce, the typical inclusions in the steel were Al2O3, MnS and Al2O3-MnS, with an average size of approximately 2.51 μm and an irregular or stripe morphology. Upon the addition of rare earth Ce, the inclusions in the steel were transformed into Ce-S(-O), Ce-As(-O) and Ce-S-As(-O), with a smaller average size and a spherical or ellipsoidal morphology. The smallest average size of inclusions in the steel was observed when rare earth Ce was added and held for 5 min; this size was 33% smaller than that prior to the addition of Ce. The thermodynamic calculation revealed that the Ce-S(-O) inclusion is formed in molten steel, while the Ce-As(-O) inclusion is formed during the solidification stage. As element replaced parts of the S and O elements in the Ce-S(-O) inclusion and formed the Ce-S-As(-O) complex inclusion, characterized by a double-layered structure.

A comparative study on adhesive properties of nanoparticle reinforced epoxy bonded single-strap repaired composites

Abstract This study aimed to evaluate the impact of nanoparticle inclusion and patch size on the bonding performance of single-strap repaired glass-reinforced composite plates through experimental investigations. Epoxy adhesive was modified with three different nanoparticles: nano-silica (NS), nano-graphene (NG), and nano-clay (NC) at varying weight contents. The patch repair performance of the test samples was evaluated using two patch ratios (Patch diameter (D)/Hole diameter (d) = 2 and 3) to explore the influence of patch size on repair effectiveness. GFRP composite base plates having a 10 mm diameter hole in the middle were patch repaired by using patches with the same material. Tensile tests were conducted to compare the tensile performance of the repaired composite samples, and the results were compared with the samples with and without holes. Based on the findings, it was noted that samples with a larger patch ratio (D/d = 3) can withstand higher tensile loads compared to those with a patch ratio of 2. Moreover, it was found that the specimen repaired with 3 % by weight NC-filled epoxy adhesive showed the greatest increase in tensile load value. This increase was recorded at both patch rates, with a percentage improvement of 2.8 and 19.54 % compared to pure epoxy adhesive. Also, it was observed that when the patch ratio was 3, the 3 % NS-filled adhesive showed an increase of 3.3 %. On the other hand, all combinations of NG-filled adhesive showed a decrease in maximum tensile load values.

Dual composite architectonics: Behavior of ZrB2–SiC–TaB2 composites under abrasive conditions

The influence of abrasive impact on ZrB2–SiC–TaB2 ceramic composites with homogeneous distribution of components in ZrB2 matrix and with «dual composite » structure (ZrB2–SiC)-(TaB2–SiC) has been studied. It was shown that at the same content of components the abrasive wear of the ceramic with the «dual composite » structure is significantly less than that of the composite with homogeneous distribution of single-phase components in a single-phase matrix. On the surface of the studied composites there were no furrows and grooves typical for the abrasive action on the material. At abrasive impact on ceramic composite with homogeneous distribution of components there was a formation of subsurface cracks with the subsequent tearing off of material segments with the size exceeding the size of inclusions in the matrix. Abrasive wear of ceramics with the «dual composite » structure at a high content of composite inclusions occurs by "erosion" of the matrix at the interface with composite inclusions with subsequent removal of inclusions. Composites with «dual composite » structure had higher residual strength compared to ceramic with homogeneous distribution of components. It was found that the difference in the character of abrasive wear of composites is largely in relation to the distribution of residual stresses formed due to the difference in the thermal linear expansion coefficients of the components.

Initiation and evolution of butterflies in roller bearings due to rolling contact fatigue

This investigation entails analysis of 520 butterfly formations (BFs) and non-metallic inclusions without BFs in two RCF-tested roller bearings to elucidate the influence of inclusion characteristics and stress level they are subject to, on the initiation and growth of BFs. The results show duplex inclusions, though least frequent in the bearing steels, exhibit the highest butterfly formation rate comparing with pure sulphide/oxide inclusions. It is also found that larger inclusions and those with smaller aspect ratios are more prone to butterfly formation; BF wing length decreases with the increase of inclusion aspect ratio; BF orientation is significantly influenced by inclusion size and stress level; stress magnitude appears to either impede or facilitate BF wing growth depending on BF orientation.

Study of the Microstructure of 08PS Steel Deoxidized with Standard Ferroalloys and Prospects for Replacing Them with Complex Deoxidants

The annotation This research work is devoted to the study of the microstructure of 08PS steel deoxidized using standard ferroalloys and the prospect of replacing them with complex deoxidifiers. The purpose of the study was to determine the impact of the deoxidation process on the microstructure of steel and to assess the replacement with complex deoxidants. Research methods included metallographic analysis of steel samples and energy dispersion analysis (EDX) to determine the composition of non-metallic inclusions. The analysis was carried out on steel samples before and after deoxidation, the microstructure, the size of non-metallic inclusions and their composition were studied.

Numerical and analytical studies of attenuation coefficient in 2D matrix-inclusion composites with randomly distributed circular inclusions

This paper studies the analytical and numerical evaluation of the scattering-induced attenuation coefficient of elastic waves in 2D matrix-inclusion composites with a random distribution of inclusions. An analytical self-consistent homogenization method is recalled to estimate the phase velocity and attenuation coefficient. Afterward, a finite element-based numerical approach is introduced for calculating the phase velocity and attenuation coefficient. The analytical and numerical results are compared for different area fractions and inclusion sizes, and the limitations of both methods are investigated. It is shown that the results are in good agreement when the area fraction of inclusions is less than 10%. Due to the limitation of the analytical approach, the numerical method is used for obtaining the attenuation coefficient of a particular 3D-printed composite with a quasi-incompressible matrix used for replicating the biological tissues in ultrasonic imaging.

Micromechanical model for effective thermoelectric properties of thermoelectric composite containing ellipsoidal inclusions with interfacial resistances

The effective design of thermoelectric composites is of great significance in improving performance of thermoelectric composites. Herein, we develop a homogenization theory to predict the effective thermoelectric properties of thermoelectric composite containing ellipsoidal inclusions whereby interfacial thermal and electrical resistances are considered. Firstly, the closed-form representations of the effective thermoelectric properties are derived under the assumption of a small temperature difference. Then the effective properties of the thermoelectric composite subjecting to a large temperature difference are obtained by cutting the composite to a serial connection of pieces with a small temperature difference. The relationship between the interfacial resistances and the effective properties of thermoelectric composites is discussed systematically under the different conditions of the aspect ratio, volume fraction, size of inclusion and temperature difference in the composite. Our theoretical predictions well match the effective properties obtained from finite element analysis.

Observation of flaking process in rolling contact fatigue of bearing steel with spheroidal inclusions by laminography using ultrabright synchrotron radiation X‐rays

AbstractRolling contact fatigue tests were performed on specimens containing spheroidal inclusions to clarify the effect of the orientation of inclusions, and the results were compared with those of specimens containing stringer‐shaped inclusions. For all types of inclusion, cracks first formed on the rolling surface and then propagated in the depth direction, and an internal crack parallel to the rolling surface formed from the deepest point of the vertical crack, which led to flaking. The flaking life of the specimens with spheroidal inclusions was longer than that of the specimens with stringer‐shaped inclusions, where the initiation and propagation lives of cracks were affected by the inclusion shape and size. The surface crack initiation life was shorter for specimens with longer surface inclusions, whereas the crack propagation life decreased with the depth of surface inclusion. The greater the scatter of the size of inclusions, the greater the scatter of flaking life.

Influence of Ti/N Ratio on Inclusions, Microstructures, and Toughness in Heat‐Affected Zone of Shipbuilding Steel Plates with Mg Deoxidation after High Heat Input Welding

The inclusions, microstructures, and toughness in heat‐affected zone (HAZ) of the shipbuilding steel plates with Mg deoxidation and the different Ti/N ratios are studied after the high heat input welding of 400 kJ cm−1. With increasing the Ti/N ratio from 3.00 to 5.67, the average size of inclusions increases, the mass fraction of total TiC inclusions increase from 2.8% to 5.0%, and the average size of MgO–TiN–MnS increases from 2.82 to 5.49 μm, while the number density that can induce intragranular acicular ferrite (IAF) nucleation decreases from 87 to 62 mm−2. These changes in inclusions are detrimental to induce the IAF nucleation. The HAZ microstructures are composed of the IAFs, polygonal ferrites, and upper bainites (UBs). With increasing the Ti/N ratio, the area fraction of the IAFs decreases from 44% to 14%, and the area fraction of UBs increases from 1.8% to 9.5%. The HAZ fracture mode changes from ductile fracture to brittle fracture after the high heat input welding of 400 kJ cm−1, and the HAZ toughness decreases from 183.3 to 48.7 J at −20 °C.

Investigation of the effect of ultrasonic treatment during crystallization on the structure and properties of deformable aluminum alloys

The article presents the methodology and results of the study of the effect of ultrasonic treatment of the melt of deformable aluminum alloys during crystallization on the structure and properties of the formed ingots: the dependence of the grain score, porosity, size and distribution of inclusions of intermetallides on the amplitude of ultrasound radiation and the frequency of vibrations, as well as the distance to the waveguide. In addition, data on the analysis of the transformation of iron‑containing phases (α‑AlFeSi and β‑AlFeSi) under the action of ultrasound and dissolution of titanium waveguides during ultrasonic treatment of aluminum melt are presented.

Automated feature analysis as a tool for non-metallic inclusion analysis in solidified metals

In-depth analysis of the non-metallic inclusion population in solidified metals is essential considering the high cleanliness requirements for metallic components. For this purpose, automated feature analysis (AFA) is a powerful inclusion analysis tool, providing statistical supported information about quantity, elemental composition, morphology and size of inclusions. However, thorough data evaluation is imperative to ensure accurate and reliable results. The paper introduces the key principles of evaluating AFA data, emphasizing its capabilities and constraints by utilizing four large datasets obtained from solidified steel blocks, each containing a minimum of 4000 features. Additionally, methodologies for identifying characteristic inclusion species within a dataset, constructing suitable rulefiles for inclusion classification through statistical analyzes, and interpreting the resulting outcomes are presented. The size distribution of inclusions is analyzed using population density functions, focusing on the absolute inclusion count within specific size ranges. Cluster analysis is presented considering the inclusions‘ positional parameters.

Oxide Inclusions in Aluminum-deoxidized Ultra-low CarbonSteel

RH (Ruhrstahl-Heraeus) degassing process was confirmed to be an effective method for making the steel cleaner by comparing the samples before and after RH degassing, mainly on the area of the total inclusion, the total number of inclusions, the mean area of inclusions, and inclusion size distribution. Four main types of inclusions including alumina and titanium oxides, and Al-Ti-O complex oxides were studied by analyzing their formation mechanisms, compositions, and morphology using SEM (scanning electron microscope) and EDS (energy-dispersive X-ray spectroscopy). Thermodynamic analysis through kinetic simulations of the different stages of RH degassing was conducted by the FactSageTM software package. Based on the equilibrium amount of oxides in the liquid steel, the effects of system temperature, oxygen contents, and alloy additions on the formation of inclusions and nozzle clogging were discussed to improve the steel’s cleanliness.

TiN inclusions distribution in the composite cross section of Titanium Micro-alloyed Steel slab: thermo-chemical modeling and automatic statistic analysis

A model for TiN (Titanium Nitride) inclusions precipitation was developed to investigate the precipitation and growth behavior of TiN inclusions during slab solidification for the entire cross-section of Titanium Micro-alloyed Steel (0.0077 wt%N, 0.12 wt%Ti) slabs. The model integrates the principles of heat transfer, thermodynamics, and kinetics to predict the size and concentration of TiN inclusions in slabs. The outcomes of the TiN inclusions precipitation model showed that the TiN inclusions size on the surface of the slab was 2.82 μm, the central TiN inclusions size was 10.07 μm, and the total TiN inclusions concentration was 0.073 wt%. The distribution of TiN inclusions in the slabs was ascertained by automated scanning electron microscopy/energy dispersive X-ray spectroscopy inclusion analysis (AZtec Steel system). The results showed a sharp decrease in the number density of TiN inclusions number and an increase in the average size from the surface to the center of the slab. The model validation revealed that the model might accurately simulate the maximum size of TiN inclusions in the slab. However, the presence of micron-sized TiN particles in the steel matrix resulted in an overestimation of the modelled TiN concentration as compared to the actual TiN concentration.

Influence of the Structural-Phase Composition of the Initial Charge Material on the Qualitative Characteristics of Castings from Al-Si-Mg System Alloy

Introduction. The work focuses on solving quality problems of castings made of Al-Si-Mg alloy (AK9). The paper draws attention to the absence of a unified theory of alloy modification and the need to find solutions that ensure good product quality. The reasons for bad quality due to the weak justification of the choice of the manufacturer of the initial charge material — ingots are considered. Ingots from two suppliers are compared in terms of the structural-phase state. The paper shows how it causes defects in castings. The inefficiency of traditional methods of suppressing the formation of brittle plates of the iron-containing phase in the alloy of the Al-Si-Mg system due to the presence of Mn in the chemical composition of the alloy is noted. If the specified flaw is inherited from the source material, the generally accepted approach does not work. The article formulates the recommendations for solving this problem. The introduction of the proposed approach into production practice can open the way to solving an important applied task — to improve the wording of tasks for tenders. The relevance of the study is due to the widespread use of alloys of the Al-Si-Mg (AK9) system in modern mechanical engineering, including in aerospace structures. The work objective is to study the influence of the structural-phase state of the source material on the qualitative characteristics of finished castings from the Al-Si-Mg alloy system.Materials and Methods. Eight casts were analyzed, in which ingots from two manufacturers were used. Radiography revealed a correlation between the fracture structure of castings, structure and quality indicators. Scanning electron microscopy was used to analyze the microstructure and chemical composition of the phases. When setting quality requirements, the authors proceeded from the existing industry and state standards. The conditions of heat treatment of samples were taken from the same documents. The spectrograms were visualized as graphs showing the intensity of the element peak in the Auger spectrum and the energy of the electrons resulting from the Auger effect.Results. The results of radiography gave grounds to assert that the products provided by supplier No. 1 had significant advantages in terms of quality. If we focused on the industry standard, the exclusion of the 2nd supplier's ingots from the process ensured the production of products without casting defects at the level of 73 %. Otherwise, this figure did not exceed 57 %. The rejection indicators were discontinuities, clusters of flaws, high porosity. After melting 5-8, which involved the materials of the 2nd manufacturer, the fractures of the samples after rupture were investigated. Locations with smooth, viscous and mixed relief are highlighted. An increase of up to ×500 made it possible to establish insignificant areas with a viscous relief, which was characteristic of brittle fracture by the cleavage mechanism. The absence of inclusions and liquations was established. The microstructure of the sections from discontinuous samples was considered. It turned out that it corresponded to the modified and heat-treated state of the AK9ch alloy without signs of burnout. Individual dark needle-like phases and single pores were noted. The conditions of dispersed Si precipitations, Al32Si10Fe5Mn and Al37Si5Fe5Mn chipping, as well as the separation of the Al36Si3Fe6Mn3 phase in skeletal form were described. The advantages of the microstructure of ingots samples from manufacturer No. 1 were listed. It corresponded to the modified state of the AK9ch alloy. The branches of dendrites and the sizes of silicon inclusions were smaller. Needle-like phases of AlxSiyFezMnq were not detected.Discussion and Conclusion. Light areas in the castings fractures were formed by a brittle fracture mechanism, which is due to the presence of AlxSiyFezMnq phase plates in the alloy structure. If iron-containing phases are inherited from the source material, then traditional methods of suppressing formation do not lead to the creation of compact equiaxed polyhedra. To improve the quality of castings, it is recommended to use ingots with a pre-modified structure, without including phase plates of variable composition AlxSiyFezMnq. The results obtained can be used, among other things, to justify the requirements for the material during tenders, which will enable the enterprises of the machine-building industry to improve the quality of products and reduce the cost of marriage. As a result, this will increase their competitiveness in the Russian and world markets.

Irregular pitting propagation within the inclusions in Ce-doped Fe40Mn20Cr20Ni20 high-entropy alloy

Comprehensive investigations on the impact of Ce doping on the pitting resistance of Fe40Mn20Cr20Ni20 high-entropy alloys in 3.5% NaCl solution were conducted with an emphasis on the inclusions involved. The correlation between the variations of the type, number and size of inclusions and the doping of Ce were identified. The increased pitting resistance of the alloy induced by the doping of Ce was found associated with higher metastable pitting potentials and steady-state pitting potentials. The morphology evolution with the inclusions captured by SEM images and EDS mapping strongly indicated an existence a double-layer structure in Ce-doped Fe40Mn20Cr20Ni20 high-entropy alloys. An evident irregular pitting propagation path was probed in Ce-doped samples.