Final Texture Research Articles

Surface texture generation using high-feed milling with spindle speed modulation

This paper presents a new surface texturing technique using ball-end milling with high feed speed and spindle speed modulation. The ratio between feed-rate and cutting tool radius is in the range of 0.2–0.4, which is much larger than the ratio in conventional milling. Sinusoidal modulation signal is added, so the spindle speed becomes time-varying in order to generate different texture profiles. The cutting tool kinematics are modeled considering the tool-tip run-out and deflection due to cutting forces. The effects of amplitude and frequency of the modulation signal on tool-tip trajectories and surface textures are simulated and analyzed. The relationship between the micro features of the surface texture and the process parameters are investigated. Surface texturing experiments are conducted based on the proposed technique, and tribology tests are performed on the textured surface. It is shown that the textured surfaces present frictional anisotropy, which depends on the process conditions and modulation parameters. The proposed technique is able to achieve fast generation of various surface textures without additional instrumentation, and the final texture geometry is controllable based on the presented kinematics model.

Hot Rolling of Magnesium Single Crystals

To analyze the effect of the initial orientation in the activity of twinning and texture development, magnesium single crystals were rolled at 400 °C (nominal furnace temperature) in two specific orientations. In both orientations, the rolling direction of the sheet (RD) was parallel to the c-axis. For orientation 1, the 112¯0 direction was parallel to the normal direction (ND), and for orientation 2, it was parallel to the 101¯0 direction. The samples were rolled at 30%, 50% and 80% of thickness reduction. After rolling, all the samples were quenched in water to retain the microstructure. The microstructure and texture evolution were characterized by X-ray diffraction and Electron Backscatter Diffraction (EBSD). The initial single crystals were turned into polycrystals, where most grains had their c-axis almost parallel to the ND, and this reorientation was explained by extension twinning. The active twin variants in orientation 1 aligned the basal plane ~30° from the sheet plane and caused a weaker basal texture compared to orientation 2, where the twin variants aligned the basal plane almost parallel to the sheet plane. Strain localization inside contraction twins was observed, and consequently, non-basal grains nucleated inside these twins and weakened the final basal texture only in orientation 1.

Microstructure Evolution during Accelerated Cooling Followed by Coiling of an Nb-Ti/HSLA Steel

An Nb-Ti low carbon HSLA steel with the application of Coiled Tubing steel in petroleum industry, was subjected to hot rolling followed by the subsequent cooling procedures including cooling and coiling. The effect of cooling rate and coiling temperature on final microstructure and texture was investigated via optical microscopy, SEM, and EBSD analyses. It was found that rolling at 800 °C results in the appearance of elongated ferrites due to the activation of the deformation-induced ferrite transformation mechanism. Cooling from the finish rolling with different rates of 2.4 to 15 °C/s leads to the formation of polygonal ferrite and retained austenite. Higher cooling rate increases the retained austenite, decreases the ferrite grain size and improves the grain size homogeneity. Coiling at 600 °C results in coarser ferrite with the texture of γ fiber which is due to the recrystallization of ferrite. On the other hand, coiling at 500 °C intensifies the {332} $$\left\langle {113} \right\rangle$$ and {113} $$\left\langle {110} \right\rangle$$ components indicating deformed austenite transformed to ferrite.

The Origin of the Cube ({001}) Texture in Non-oriented Electrical Steel Sheets

Although cube ({001}<100>) is a preferred final texture in non-oriented electrical steel (NOES) sheets, this texture is rarely produced in commercial NOES products. The major texture of fully processed NOES is usually the unfavorable <111>//ND (normal direction) fibre, which originates from the deformed <111>//ND texture. To reduce/eliminate the <111>//ND texture and promote the cube texture, one method is to change the initial texture before cold rolling. In this research, two electrical steels containing 0.88 wt% and 2.8 wt% Si are cold rolled with the initial textures rotated by 60° around the ND before cold rolling. This rotation leads to the rotated Goss ({110}<110>) texture in the deformed microstructure. Within the shear bands of the rotated Goss grains, crystallites with cube orientation are formed. Regions of these crystallites may have lower stored energy than their neighboring areas. During annealing, these crystallites preferentially nucleate and grow, and form a strong cube texture in the final steel sheets.

ASSESSING THE INFLUENCE OF ON-SITE LIGHTING CONDITIONS TO THE POTENTIAL VARIABILITY OF THE 360 ° PHOTOGRAMMETRY USABILITY

Today's technologies enable efficient data management and generally contribute to effective control of the construction process. There are various ways of focusing on a real construction project based on laser or digital camera measurements, however, the quality of outputs is depending on the lighting conditions. Proper lighting conditions greatly affect the result of the processed record, especially its final texture, geometry, and affect any errors in the measured values. There are various lighting conditions on the construction site, which affect the quality of the documentation made. While in the outdoor parts this situation is affected by daylight, inside the building we must rely on artificial lighting and as a result there are many parts without sufficient lighting, or the lighting is completely absent.In this article we focus on the evaluation of the impact of lighting in documenting the course of work on the site using 360 ° photogrammetry, especially in relation to verification of geometric accuracy, position of structures and current work in progress and follows the analysis of standard and technical requirements to determine appropriate ways to ensure adequate lighting.

Shear Banding in Rotated Goss Grains and its Effect on the Formation of Cube Texture in Non-Oriented Electrical Steel

Cube texture ({001}&lt;100&gt;) is a desired final texture in non-oriented electrical steel sheets used as magnetic cores because it contains two easy &lt;100&gt; axes in the sheet plane, which is beneficial to the magnetic properties. However, the cube texture is very difficult to form in non-oriented electrical steels through conventional rolling and annealing. It has been shown that after conventional rolling, the deformed &lt;111&gt;//ND (normal direction) grains provided nucleation sites for the unfavourable &lt;111&gt;//ND texture during recrystallization, leading to a final &lt;111&gt;//ND texture. To eliminate the &lt;111&gt;//ND texture and promote the {001}&lt;100&gt; texture, an uncommon rolling process, i.e. inclined rolling, was adopted in this study. By rotating the hot rolling direction by 60° around the ND, an uncommon initial texture, the rotated Goss ({110}&lt;110&gt;), was intentionally generated. This was intended to change the orientation flow during plastic deformation, and suppress the formation of the conventional &lt;111&gt;//ND texture in the deformed microstructure. Plane-strain compression (rolling) of the rotated Goss grains produced shear bands within these grains due to their large Taylor factor. Electron backscatter diffraction (EBSD) characterization of the shear bands illustrated that, crystallites with the cube orientation were formed within these shear bands. During recrystallization, the shear bands provided preferential nucleation sites, and the cube crystallites preferentially nucleate within the shear bands. These cube crystals can then grow into the deformed matrix, and lead to the formation of a strong cube texture in the final annealed steel sheets.

Drying Characteristics of Jackfruit and Snake Fruit using Freeze Dryer

Jackfruit (Artocarpus heterophyllus Lam.) and snake fruit [Salacca zalacca (Gaert.) Voss] are tropical fruits that are rich in vitamins and minerals. Due to their specific aroma and unique taste, jackfruit and snake fruit have great potential to be processed into dried fruits and healthy snacks. In this work, jackfruit and snake fruit were freeze-dried using a self-designed laboratory-scale freeze dryer. The freeze dryer was constructed with a stainless-steel plate (3 mm thickness). The drying rates were determined with three different heating temperatures: 50, 60, and 70ºC. This study also investigated the effect of the freeze-drying process on the characteristics of dried fruit such as moisture content, texture, color, ascorbic acid content, and morphological of dried samples. Results showed that the heating temperatures were revealed to affect characteristics such as drying rate, final moisture content, texture, and ascorbic acid content. Increased drying rate and decreased drying time were observed with an increase in the dryer temperature. The sample resulted from 70ºC of heating temperature exhibited the optimum results in terms of hardness and ascorbic content preservation. The first-order kinetic model was the best fit for the prediction of drying kinetics of all materials.

Relationship among solution heating rate, mechanical properties, microstructure and texture of Al−Mg−Si−Cu alloy

Abstract The relationship among heating rate, mechanical properties, microstructure and texture of Al−Mg−Si−Cu alloy during solution treatment was investigated through tensile test, scanning electron microscope, X-ray diffractometer and EBSD technology. The experimental results reveal that there is a non-monotonic relationship among solution heating rate, mechanical properties, microstructure and texture. As the solution heating rate increases, the strength variations are dependent on the tensile direction; work hardening exponent n decreases first, and then increases; plastic strain ratio r increases first, and then decreases, and finally increases. The final microstructure and texture are also affected by heating rate. As heating rate increases, the microstructure transforms from elongated grain structure to equiaxed grain structure, and the average grain size decreases first, and then increases, and decreases finally. Although the texture components including CubeND{001}〈310〉 and P{011}〈122〉 orientations almost have no change with the increase of heating rate, the texture intensity and volume fraction decrease first, and then increase, and finally decrease. Both microstructure and texture evolutions are weakly affected by heating rate. Improving heating rate is not always favorable for the development of fine equiaxed grain structure, weak texture and high average r value, which may be related to the recrystallization behavior.

The role of grain colony on secondary recrystallization in grain-oriented electrical steel: New insights from an original tracking experiment

Secondary recrystallization is responsible for the sharp Goss texture ({110}<001>) of grain-oriented electrical steels. Many investigations have focused on establishing the relations between the sharpness of final Goss textures and primary recrystallization textures measured by the X-ray diffraction. However, the contributions of micro-texture characteristics to secondary recrystallization have not yet been well understood. Here, we report that the grain colonies composed of grains with similar orientations in the primary recrystallization matrix had a particular role on the development of secondary recrystallization via an original tracking experiment. We observe that the γ-grain (<111>//normal direction, ND) colonies facilitate the retention of primary recrystallization matrix grains (≤25µm) having 20-45° disorientation with {110}<001> and relatively large difference in the associated frequency with precise Goss orientation and that having deviation angle of 15°, promoting the abnormal growth of low-deviation-angle Goss grains especially after the onset of secondary recrystallization and leading to sharp final Goss texture. By contrast, the abnormal growth of high-deviation-angle Goss grains may be also promoted after the initiation of secondary recrystallization in case of randomly-distributed γ-grains in primary recrystallization matrix and thus resulted in deteriorated magnetic properties. In this way, we reveal the role of grain colony on secondary recrystallization and the underlying mechanism for the effect of primary recrystallization textures on the sharpness of final Goss texture. We also observe that the formation of grain colonies is mainly related to the initial solidification microstructure, processing route as well as the deformation and recrystallization features of γ-grains.

Explaining the dilatometric behavior during bainite transformation under the effect of variant selection

The selection of crystallographic variants in bainitic microstructures is a deeply studied topic which can be attributed to several reasons. In the cases where the prior austenite is textured, stressed or plastically deformed, the final ferrite texture and the dilatometry signal may change, being anisotropic. Although the causality between variant selection and the variation of the dilatometric signal has been previously assumed, it has not been thoroughly proved. In this work, the phenomenological theory of martensite was combined with a continuum mechanics analysis to calculate the relative length changes associated to the bainitic transformation during different bainitic transformations in order to prove the connection between the selection of crystallographic variants and the distortion of the dilatometry signal. To do so, four different bainitic microstructures were analyzed: one of them obtained by a pure isothermal treatment and the rest of them obtained by ausforming treatments. Some of the mentioned microstructures had shown to lead to negative longitudinal dilatometry signals and to present a strong variant selection. Results showed that the experimental trends could be explained by theoretical means, which enables to further understand the bainitic transformation.

Tracing the recrystallization of warm temper-rolled Fe–6.5 wt% Si non-oriented electrical steel using a quasi in situ EBSD technique

Fe–6.5 wt% Si non-oriented electrical steel is an excellent soft magnetic material due to the low core losses at high frequencies and near-zero magnetostriction. In this study, an Fe–6.5 wt% Si non-oriented electrical steel was processed by hot rolling, warm cross rolling, intermediate annealing, warm temper rolling and final annealing. The evolution of microstructure and microtexture during final annealing was investigated using a quasi in situ EBSD (electron backscatter diffraction) technique. After warm temper rolling, an area on the ND–RD (normal direction–rolling direction) cross section was marked by micro-hardness indents, and the recrystallization of individual grains in this area was traced under EBSD when the annealing time was increased. Due to the differences in the microstructure, texture and stored energy after warm temper rolling, the surface and center regions showed different recrystallization behaviors. The recrystallization of the surface region was essentially initiated by the growth of existing crystallites having lower stored energy than their neighboring areas (essentially no nucleation), while the center region showed both nucleation and grain growth during annealing. The growth rates of individual grains were evaluated with respect to the number of neighboring grains, and they approximately followed the von Neumann–Mullins law of grain growth. The surface region showed a much faster growth rate than the center region. The final texture was dominated by //ND and //ND in both the surface and center regions, due to the preferred growth of these grains.

Interactions between tapioca starch and Mesona chinensis polysaccharide: Effects of urea and NaCl

Non-starch polysaccharide and starch interactions have been extensively studied. However, few researches focus on their interactions mechanism. In this study, the effects of hydrogen bond and electrostatic interactions on the tapioca starch-Mesona chinensis polysaccharide (TM) gels were investigated. The results of pasting and thermal experiments (heating phase) showed that the peak viscosity (PV) of TM gels increased with the addition of urea. The addition of urea caused the hydrogen bonds to be destroyed and the rearrangement of starch during cooling was inhibited, which led to the final viscosity of TM gels decreased. The interactions between 0.5% NaCl and starch hydroxyl groups resulted in a significant increase in PV, while excessive addition of NaCl produced an electrostatic shielding effect, resulting in a decrease in PV, but still higher than TM gels. The results of rheological, texture, and particle size experiments (gel cooling stage) showed that hydrogen bond played a decisive role in the final texture of TM gels. Scanning electronic microscopy results showed that the addition of urea loosened the starch structure, and the high concentration of urea caused the structure appear fragmented.

Starch properties of high and low amylose proso millet (Panicum miliaceum L.) genotypes are differentially affected by varying salt and pH

Variation in salt content and in pH are common in starch-based foods and can affect starch properties and final product texture. Fifteen accessions of proso millet starch with diverse amylose content were selected to investigate single factor and interaction effects of pH and NaCl on thermal, pasting, and textural properties. Pasting properties and gelatinization temperatures were markedly altered by salt addition. Changes in pH only had substantial effects on ΔH, but other properties were generally stable under different pH conditions. From two-way ANOVA, interactive effects of salt and pH were found to affect ΔH. The response of starch of different genotypes in terms of thermal and pasting properties differed under the same pH and salinity conditions. The reason is likely that ions in the starch–water system performed the roles of both reducing water activity and building of hydrogen bonds, which will have opposite effects on starch gelatinization.

Texture evolution of non-oriented electrical steel analyzed by EBSD and in-situ XRD during the phase transformation from γ to α

If the phase transformation from γ to α is properly controlled in silicon steel, the cube texture is known to be produced. Two sheet samples of Fe-2 wt%Si-1 wt%Ni and Fe-3 wt%Si-2.5 wt%Ni were heated to 1100 °C, held for 2 h and then cooled. The inverse pole figure (IPF) map and the orientation distribution function (ODF) of the two samples indicate that the {100} texture is dominant in the Fe-2 wt%Si-1 wt%Ni sample whereas the {112} texture is dominant in the Fe-3 wt%Si-2.5 wt%Ni sample. In order to understand why such drastically different textures were evolved, the in-situ X-ray diffraction (XRD) analysis was made during heating and cooling of the two samples. The XRD peaks of Fe-2 wt%Si-1 wt%Ni indicate that 1100 °C is one phase region, which affects strong {100} texture by preferred orientation during cooling. However, 1100 °C is the (α + γ) two phase region for the Fe-3 wt%Si-2.5 wt%Ni. Therefore, the final texture was affected by remained orientation, which leads to strong {112} texture. This difference is attributed to the evolution of such drastically different textures between the two samples.

Two-stage warm cross rolling and its effect on the microstructure, texture and magnetic properties of an Fe-6.5 wt% Si non-oriented electrical steel

Cross rolling is an effective processing technique used to optimize the crystallographic texture of electrical steel sheets. However, it is usually applied in cold rolling only. It is unknown how this rolling technique affects the microstructure and texture of electrical steels at elevated temperatures. In this study, a two-stage warm cross rolling scheme, i.e., rolling at elevated temperatures and in alternative directions with respect to the hot rolling direction (HRD), was applied to an Fe-6.5 wt% Si non-oriented electrical steel to produce thin steel sheets. The swapping of rolling direction between the two warm rolling stages significantly changed the deformation microstructure and texture, leading to different final recrystallization textures. These differences are attributed to the discrepancies in slip activities at elevated temperatures and to the different initial textures resulted from the change in rolling direction. The magnetic properties of the final steel sheets are evaluated by single sheet testing. Although the steel processed by warm rolling along HRD in the first stage and along HTD in the second stage exhibits a slightly higher magnetic flux density than other routes, it is shown that the magnetic flux density and core loss may have little relation to the crystallographic texture since the magnetocrystalline anisotropy caused by the texture is small.

Transformation textures in pure titanium: Texture memory vs surface effect

Surface effect-induced phase transformation heat treatment is performed on cold-rolled commercial pure titanium sheet to change and control the transformation texture. The results show that the type of final transformation texture changes from the texture memory effect type texture of TD-split basal to the surface effect type texture of 〈11−20〉//ND with the increase of heating temperature in helium atmosphere. At a low heating temperature of 920 °C and 1000 °C, the textures in sheets exhibited texture memory effect, while in the high heating temperature of 1100 °C, it showed the effects of both anisotropy in elastic modules of HCP titanium crystals and transformation strain. During the cooling phase, the surface effect can promote the preferred nucleation of α-phase grains on the plate surface, and then grow to the center layer of sheet along the ND direction. In the process of preferential nucleation of surface grains, texture memory effect and surface effect are a competitive process. The result of competition often shows that the small grains with tilted basal orientation (red) and cylindrical orientations (blue-green) are nucleated on the surface together, and the grains with blue-green orientation have the advantage of growth, leading to different grain morphology and microstructure. In addition to heating temperature and protective atmosphere, the degree of recrystallization before phase transformation also significantly affects the type of transformation texture. These differences in transformation texture and microstructure are explained according to the mechanism changes of the factors influencing the variant selection.

Vortex fluidic mediated one-step fabrication of polyvinyl alcohol hydrogel films with tunable surface morphologies and enhanced self-healing properties

Previous strategies for controlling the surface morphologies of polyvinyl alcohol (PVA)-based hydrogels, including freeze-drying and electrospinning, require a post-treatment process, which can affect the final textures and properties of the hydrogels. Of particular interest, it is almost impossible to control the surface morphology during the formation of PVA hydrogels using these approaches. The strategy reported in this study used the novel vortex fluidic device (VFD) technology, which for the first time provided an opportunity for one-step fabrication of PVA hydrogel films. PVA hydrogels with different surface morphologies could be readily fabricated using a VFD. By also reducing the crosslinking agent concentration, a self-healing gel with enhanced fracture stress (60% greater than that of traditionally made hydrogel) was achieved. Interestingly, the associated self-healing property remained unchanged during the 260-s mechanical testing performed with the strain rate of 5% s−1. The VFD can effectively tune the surface morphologies of the PVA-based hydrogels and their associated properties, particularly the self-healing property.

The cooling process effect on the bilayer phase state of the CTAC/cetearyl alcohol/water surfactant gel

Gel formation by surfactant molecules is generally controlled by thermodynamics rather than kinetics. Mixtures of long-chain alcohols and surfactants are widely used in various cosmetic and pharmaceutical products. The cooling rate used to produce the products is known to be a key parameter to control the rheological properties and the final texture. However, the physical-chemistry links between the cooling process and the rheological properties are still unknown. Here, we investigated the mechanical properties and microstructure of a surfactant gel formulated with cetyltrimethylammonium chloride (CTAC) and cetearyl alcohol in water by using a multi-technique approach involving rheology, small-angle X-ray scattering (SAXS) and diffusion NMR. The gels, formed by two cooling processes fast and slow cooling, respectively from a high-temperature mixture, have locally a lamellar structure with periodic repeat distances of 31.4 and 28.5 nm for fast and slow cooling, respectively. The cross-polarized microscopy images reveal the presence of multilamellar vesicles (MLVs). These data on the supramolecular aggregates allow rationalizing the mechanical behavior of the two samples. In fact, the elastic, G′, and the viscous, G′′, moduli were detected to be ca. 4 times higher for the fast-cooling (quenched) sample than for the slow-cooling (relaxed) sample.

Microbial weathering signatures in lateritic ferruginous duricrusts

Iron-rich duricrusts (canga) that blanket iron ore deposits in tropical regions in Brazil have a complex formation and evolution. The direct role of microorganisms in the biogeochemical cycling of iron and remarkably aluminium, which is critical for the preservation of these duricrusts, is becoming more apparent. In this study we combine nanoscale secondary ion mass spectrometry (NanoSIMS) with Raman spectroscopy and scanning electron microscopy to distinguish highly weathered and recycled grains, portions of which have been metasomatised by iron in solution, from new mineral precipitates within canga. Microbially-accelerated weathering of grains within canga appears to promote iron, aluminium and titanium oxide mineral dissolution. Anatase forms at the boundaries of rutile grains, highlighting titanium dissolution and re-precipitation at the mineral-scale. Titanium is absent from the authigenic cements in canga. Aqueous ferrous iron, which is sensitive to changes in the oxidation potential of the solution, readily oxidises and re-precipitates in the pore spaces in proximity to preserved microorganisms, leaving aluminium as the most abundant cation in solution. Changes in solution pH and/or organic chemistry causes aluminium to precipitate from solution as gibbsite that infills pore spaces as the final geological texture. Evidence for microbially-promoted weathering includes the fossilisation of microorganisms along grain boundaries, in which aluminium, titanium, chromium and iron are depleted. Immobile elements including titanium, chromium and thorium, associated with rounded fossilised biofilms also indicate that microorganisms have completely weathered grains and become fossilised in place, texturally replacing the grain in the process. Microorganisms also play a role in iron and aluminium precipitation, providing sites for mineral nucleation. These results highlight the microscale changes in oxidation potential, pH and organic chemistry throughout canga that are likely to be influenced by the microbiome and associated flora. Understanding the role of microorganisms in iron biogeochemical cycling will contribute to the accelerated re-cementation of iron-rich duricrusts after the completion of iron ore mining, providing a substrate for revegetation using native plant species. This study also sheds light on direct (microfossils) and indirect (biologically-influenced element mobility) biosignatures in iron-rich geological materials.

Enhancement of RGB-D Image Alignment Using Fiducial Markers.

Three-dimensional (3D) reconstruction methods generate a 3D textured model from the combination of data from several captures. As such, the geometrical transformations between these captures are required. The process of computing or refining these transformations is referred to as alignment. It is often a difficult problem to handle, in particular due to a lack of accuracy in the matching of features. We propose an optimization framework that takes advantage of fiducial markers placed in the scene. Since these markers are robustly detected, the problem of incorrect matching of features is overcome. The proposed procedure is capable of enhancing the 3D models created using consumer level RGB-D hand-held cameras, reducing visual artefacts caused by misalignments. One problem inherent to this solution is that the scene is polluted by the markers. Therefore, a tool was developed to allow their removal from the texture of the scene. Results show that our optimization framework is able to significantly reduce alignment errors between captures, which results in visually appealing reconstructions. Furthermore, the markers used to enhance the alignment are seamlessly removed from the final model texture.