bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Strain Path Change on Texture Evolution at Finite Strain of Multiphase Steel: Numerical and Experimental Investigations
Authors: Bouvier S. , Gardey B. , Chauveau Thierry , Bacroix Brigitte
Published: March 2009

Two-stage sequences of simple shear and/or uniaxial tensile tests conducted on TRIP800 steel sheet and supplemented by texture measurements are reported. The purpose is a better understanding of the macroscopic work-hardening behaviour and its microstructural origin. According to the previously published work on single phase ferrite steel; the peculiar macroscopic transient effect in flow stress was
mainly associated to the microstructural destabilization (e.g. reinforcement, dissolution or rearrangement of the previously formed dislocation walls). In addition, the macroscopic work-softening observed at the beginning of the second stage of cross-loading was attributed to the micro-band occurrence. Considering the actual multiphase steel, the main difference lies in the absence of the peculiar transient effect in flow stress upon cross-loading (where no macroscopic work-softening is observed) and the associated microstructural mechanisms (no formation of micro-bands). Besides, the initial texture for the actual multiphase steel is in some extent different to the previously investigated single phase steel mainly made up of the γ-fibre. Therefore, a detailed analysis of the measured deformed textures is carried out in order to investigate the contribution of the texture evolution on the macroscopic work-hardening. The computations of the orientation stability map as well as the predicted texture evolutions using the classical full constraint Taylor-
Bishop-Hill (TBH) model are performed for a better understanding of the observed texture development. The influence of the texture evolution on the shape of the stress-strain curves, as well as on the remaining symmetries of the material, is also discussed. Explicitly, we show that despite the presence of a well developed texture in the as-received and deformed material, the contribution of the geometrical hardening (i.e. textural evolution) on the macroscopic behaviour remains small compared to the microstructural one.
Monte-Carlo Version of Vertex Model Applied to Recrystallization Modeling
Authors: Piękoś K. , Tarasiuk Jacek , Wierzbanowski Krzysztof , Gerber Ph. , Bacroix Brigitte
Published: March 2009

A newly developed model based on vertex concept is presented in this paper. Contrary to its standard version, which is strictly deterministic, some concepts of Monte-Carlo type method were introduced. It makes the model more flexible and allows to introduce some parameters appearing in vertex movement equations, which are not easy to express in analytical form. Initial microstructure in the model is characterized by topology, crystallographic orientations and stored energy values of the grains. The boundary energies and mobilities are anisotropic in general. Nucleation mechanism of a given type is selected at the beginning of calculations. Deformation texture, stored energy distribution and initial microstructure are input parameters of the model. The aim of the calculations is to predict the texture and microstructure modifications during recrystallization. The model was also applied to the study of the kinetics of grain growth and recrystallization. The preliminary tests of the model are presented.
Effect of Deformation Texture Component Composition on Cube Texture Formation during Primary Recrystallization in Ni-Based Alloys
Authors: Gervasyeva I.V. , Rodionov D.P. , Sokolov B.K. , Khlebnikova Yu.V.
Published: March 2009

Deformation and primary-recrystallization textures in nickel alloys with some metals
(Nb, to 5.4%; W, to 7.4; Re, to 4.1%; Mo, to 9.3%; V, to 10.1%; Mn, to 22.1%; Al, to 12.0% and Cr, to 22.0%) has been studied depending on the content of alloying elements and the rolling temperature. The dependence of the type of recrystallization texture on the component composition of the deformation texture has been established.
EBSD Study of Annealing Twinning during Recrystallization of Cold Rolled Copper
Authors: Gerber Ph. , Baudin Thierry , Chiron Rémi , Bacroix Brigitte
Published: March 2009

In this work, EBSD (Electron Back Scattered Diffraction) measurements have been performed on deformed, partially and fully recrystallized cold rolled copper to 70 and 90 % reduction. The twin fraction as well as its existing relation with the parent crystallographic orientation has been followed in relation with respect to the recrystallized fraction. It has been shown thanks to this quantitative analysis that annealing twinning is more active when recrystallization nuclei slowly develop. The experimental observations are briefly discussed according with the twins selection principles [1].
Investigation of Local Texture Correlations in Bi-2223 High Temperature Superconductor Tapes
Authors: Godfrey Andrew , Liu Wei , Lin Dan Dan , Liu Qing
Published: March 2009

In this paper we report a study using fully automated EBSP orientation measurements on
the texture and microstructure of fully processed Bi-2223 tapes produced by the powder-in-tube
method. For the automated analysis a new unit cell describing the quasi-tetragonal Bi-2223 phase has
been developed. The texture data confirm that a strong fibre texture is produced during processing,
with the c-axis of the Bi2223 plates parallel to the tape normal direction. Quantitative analysis
suggests that the orientation density along the fibre texture is close to random. In contrast the distribution of misorientations shows significant correlations between the orientations, and is skewed towards low misorientation angles. A more detailed investigation reveals that the structure consists of colonies of plates, with low angle misorientations within each colony. Analysis of the rotation axes shows some differences as a function of misorientation angle.
The Effect of Texture on Friction of AlSl304 Stainless Steel
Authors: Azzi Marwan , Reza Bateni M. , Szpunar Jerzy A. , Jedrzejowski P. , Klemberg-Sapieha J.E.
Published: March 2009

Polycrystalline materials develop texture as a result of various manufacturing processes. In this paper the effect of texture of material on wear resistance and friction coefficient of AISI304 stainless steel samples was studied. Three different types of surface textures were produced from the same stainless steel raw material. Texture measurements were performed to obtain information from the specimen surface. Friction tests were performed using a Micro Scratch tester with the capability of monitoring acoustic emission and frictional force during scratch tests.
Crystal Plastic Finite Element Simulation of Fe-Cu Polycrystals
Authors: Hartig Ch. , Mecking H.
Published: March 2009

The plastic and elastic deformation of PM two-phase Iron-Copper polycrystals was
studied experimentally and modelled by a FEM model calculation, taking into account anisotropic elasticity and crystal plasticity. Following quantities were experimentally measured and calculated by a FEM model calculation: A local strain distribution and rolling textures. For a judgement of model predictions the orientation densities of the bcc a-fibres of Iron and of the fcc b-fibres of Copper were considered. Good predictions of the texture evolution were found in cases only, where local micromechanical interactions are not too much influenced by the heterogeneity of the microstructure. The implications of these results for the development and use of FEM schemes for modelling heterogeneous polycrystal plasticity are discussed.
Structure and Crystallographic Texture of Arthropod Bio-Composites
Authors: Raabe Dierk , Al-Sawalmih A. , Romano P. , Sachs C. , Brokmeier Heinz Günter , Yi Sang Bong , Servos G. , Hartwig H.G.
Published: March 2009

In this study we present experimental investigations on the microscopic structure,
constituent phases, and crystallographic textures of the exoskeleton of three types of decapod crustaceans, namely, lobster, crab, and horseshoe crab. The carapace of such animals is a biological multiphase nano-composite consisting of an organic matrix (crystalline chitin and non-crystalline proteins) and biominerals (calcite, phosphate). The synchrotron measurements of the crystalline chitin and of the biominerals which are embedded in the chitin-protein matrix (in case of lobster and crab) reveal strong textures. The horseshoe crab does not seem to contain notable amounts of crystalline minerals. The Debye-Scherrer images of the lobster specimen suggest that the biominerals form clusters of crystals with similar crystallographic orientation. TEM images support this suggestion. The crystallographic texture of the chitin is arranged with its longest cell axis
parallel to the normal of the surface of the exoskeleton.
Three-Dimensional Texture Analysis
Authors: Mulders J.J.L. , Day A.P.
Published: March 2009

Three-dimensional (3D) microscopy is a new and rapidly expanding area. A
DualBeam system, with both a focused ion beam (FIB) column and an electron
column, is a powerful instrument for imaging and sectioning microstructures to
generate a full 3D sample reconstruction. When an electron backscatter diffraction
(EBSD) system is attached to the DualBeam, it becomes a unique tool for making 3D crystallographic measurements on a wide variety of materials. Combining the
successive removal by FIB, with sequential EBSD maps taken with the electron beam requires clear geometric considerations and a high level of automation to obtain a decent resolution in the third dimension, including positional sub-pixel re-alignment. Complete automation allows controlled sectioning and analysis of a significant volume of material without operator intervention: a process that may run continuously and automatically for many hours. Using a Nova600, a Channel 6 EBSD system and dedicated control software, Aluminium, Nickel and Steel specimens have been examined and volumes with up to 200 slices have been successfully analysed.
Determination of an ODF from Diffraction Measurements Based on Optimal Smoothing Splines
Authors: van den Boogaart K.Gerald , Hielscher Ralf
Published: March 2009

A long time has past since the introduction of the harmonic method for the reconstruction of the ODF from polefigure measurements, and it has been replaced by discrete methods of inversion, because of its incapability with respect to ghost effects. The harmonic method is still not in its best possible state: it disregards the high order harmonics; it disregards measurement errors and therefore gives suboptimal results; it does not provide standard errors, neither for the C-coefficients nor for the ODF; and there are the ghost effects. However, the harmonic method is a well established inversion method and it can improved at these points. Statistical considerations based on geostatistics and a model of the unknown ODF as a random function in a Baysian approach yields an inversion method, which can be characterized as a smoothing spline method. This new method is statistically optimal among all linear methods and resembles favorable features of the harmonic method in an improved way. It provides an optimal linear reconstruction of the even part of the ODF. It does not truncate the harmonic series expansion at a fixed level, but accounts for every even harmonic space in an optimal way with respect to its signal to noise ratio in the polefigure measurements. The method applies for irregularly sampled and incomplete pole figures. The method accomplishes standard errors for the ODF and the C-coefficients. Discrete inversion methods, explicitly or not, reconstruct the odd harmonic part of the function based on the principle of maximum entropy. Based on the theory of exponential families a continuous odd part (and the truncated even part) can be computed based on the entropy principle and the C-coefficients estimated by the spline method.
Application of Orientation Microscopy in SEM and TEM for the Study of Texture Formation during Recrystallisation Processes
Authors: Zaefferer Stefan
Published: March 2009

Orientation microscopy in TEM and SEM is a particularly well suited tool to study recrystallisation processes because these are always associated with orientation and microstructure changes. The present work discusses the possibilities and limits of the TEM and SEM based techniques and illustrates their use by means of 3 different examples. The examples include studies on nucleation mechanisms of primary recrystallisation where the techniques meet their limits in spatial resolution. The problem of in-situ observations of annealing processes is discussed and it is shown how recrystallisation simulation techniques based on experimental data may be used. Furthermore the new technique of 3-dimensional EBSD in a focused-ion-beam (FIB) SEM is presented with one example. Finally, the statistical analysis of very large orientation data sets is discussed by an example of secondary recrystallisation in electrical steels.
ODF Restoration by Orientations Grid
Authors: Savyolova T.I. , Kourtasov S.F.
Published: March 2009

The mathematical method of the texture function restoration according to diffraction
experiment is offered. The texture function is represented as superposition of standard texture functions with the identical dispersions, located on a regular three-dimensional grid in orientation space. Applicability of the method is shown by model examples and in an example of a cold rolled texture of a copper sheet.
Texture of Oxide Scales during Hot Rolling of Low Carbon Steel
Authors: Basabe Vladimir V. , Szpunar Jerzy A.
Published: March 2009

The textures of oxide scales grown on low carbon steel in air over the temperature range 850-950°C were investigated. The low carbon steel was oxidized with the air velocity of 4.2 cm/s for 10 s in order to approximate the formation of tertiary scales in hot rolling. At 850°C, the wüstite texture and magnetite texture are weak with no dominant components. For the temperatures of 900 and 950°C, the wüstite and magnetite phases have a cube texture {001}<100>. The experimental results indicate that during hot rolling in the g region, the texture of the oxide scale is cubic and when rolling in the a region, the texture of the oxide scale is weak with no dominant components.
Texture Changes of Carbon Steel and Stainless Steel as a Result of Wear
Authors: Reza Bateni M. , Szpunar Jerzy A. , Wang X. , Li Dong Yang
Published: March 2009

In this research, surface texture changes of carbon steel AISI 1045 and stainless steel AISI 304 under simultaneous wear and corrosion were investigated. A
solution of 3.5 % wt. NaCl was used as the corrosion agent and a pin-on-disk tribometer was employed to perform wear and corrosion wear tests.Texture investigations of the worn samples have shown texture changes after wear and corrosion-wear tests. In worn carbon steel samples after dry wear test, {011}<100> and {111} fiber texture components were developed in initially random oriented samples, whereas under corrosive-wear conditions, {111}<011> texture and {001}<110> texture were developed. In the stainless steel samples, {112}<110> texture component was observed under both dry and corrosive wear conditions, in the samples that had random grain orientations before corrosion and
corrosion-wear tests.
Microscale Characterisation of Deformed Microstructures of TRIP-Assisted and Multiphase Steels
Authors: Pétein A. , Ryelandt L. , Godet Stéphane , Jacques Pascal J.
Published: March 2009

The improvement of the mechanical behaviour of high performance steels brings about a renewed interest for the work hardening rate resulting from deformation-induced martensitic transformation or mechanical twinning. Even if these mechanisms are known for quite a long time, the deformation – transformation interactions that they induce is not yet fully characterised and understood. This study aims at characterising the microstructure evolution of a Fe-Mn steel grade during straining thanks to TEM and high resolution OIM. Particular patterns of austenite – e and a’ martensite are found.
Effect of Rolling Temperature, Reduction and Alloying Additions on the Texture of Warm Rolled Steels
Authors: Sánchez-Araiza M. , Godet Stéphane , Jonas John J.
Published: March 2009

The effect of warm and cold rolling parameters on the development of annealing textures was studied in two low carbon steels containing additions of chromium. Two warm rolling temperatures (640 and 700°C) were employed together with a reduction of 65%. The effects of an additional cold rolling reduction of 40% and of decreasing the heating rate during annealing were also studied. The ND fiber, <111>//ND, of the recrystallization texture was strengthened as the warm rolling temperature was decreased. However, all the warm rolled steels contained a retained RD fiber, <110>//RD. A noticeable improvement in both the continuity and intensity of the ND fiber was obtained when the sample was submitted to an additional 40% cold rolling reduction. The ND fiber was even more continuous and intense when a low heating rate was utilized, yielding r-values of 1.1 and 1.3 for the warm rolled and warm plus cold rolled samples, respectively.
Influence of Boron on Mechanical Properties and Microstructures of Hot-Rolled Interstitial Free Steel
Authors: Kim S.I. , Choi Shi Hoon , Yoo Yeon Chul
Published: March 2009

This paper examines an effect of boron (B) on dynamic softening behavior, mechanical properties and microstructures for Nb-Ti added high strength interstitial free (IF) steel. For this purpose, IF steels containing 0ppm B, 5ppm B and 30ppm B were chosen. Continuous cooling compression test was performed to investigate dynamic softening behavior. Mechanical properties and microstructures of pilot hot-rolled IF steel sheet were analyzed by uni-axial tensile test and electron back-scattered diffraction (EBSD). It was found that no-dynamic recrystallization temperature (Tndrx) which can be determined from the relationship between flow stress and temperature is a constant of 955oC for all IF steels. However, an addition of B into IF steels increases work hardening rate at the temperature below Tndrx. It was also verified that B retards phase transformation of austenite into ferrite. EBSD analysis revealed that absence of B induces fine ferrite grain size and many high angle grain boundaries.
Producing a Random Recrystallization Texture in 6111 Aluminium Alloy
Authors: Chang Cynthia S.T. , Yeung A.S.C. , Duggan B.J.
Published: March 2009

6111 Aluminium Alloy in the hot band state was cold rolled to 80% was then annealed at 450oC, 500oC and 540oC for recrystallization. The hot band was also solution heat treated, cold rolled and annealed to the same temperature to look at the difference in the recrystallization texture and precipitation states. It was found that the samples which were cold rolled and annealed without solution heat treatment gave Goss and P components after annealing. For the samples with solution heat treatment, the 450oC sample has a retained Cu type rolling texture while for the 500oC and 540oC the textures are quite random. The retained rolling texture found in the 450oC sample is due to the fact that it was partially recrystallized as the precipitates prevent complete recrystallization. The difference in the precipitation states during and after annealing of the samples with and without solution heat treatment affects the final recrystallization texture.
Texture Development in Pure Mg and Mg Alloy AZ31
Authors: Gottstein Günter , Al Samman T.
Published: March 2009

Texture evolution in pure Mg and Mg alloy AZ31 during deformation and annealing was investigated. The poor low temperature ductility can be attributed to both, insufficient shear systems and unfavorable deformation geometry. Static recrystallization was shown to proceed discontinuously despite little texture change. High temperature deformation was accompanied by dynamic recrystallization with similar texture development as during static recrystallization.
Textures Applied to Mechanical Processing Technology Assessment in Ancient Bronze
Authors: Bolmaro R.E. , Molinas B. , Sentimenti E. , Fourty A.L.
Published: March 2009

Some ancient metallic art craft, utensils, silverware and weapons are externally undistinguishable from modern ones. Not only the general aspect and shape but also some uses have not changed through the ages. Moreover, when just some small pieces can be recovered from archaeological sites, the samples can not easily be ascribed to any known use and consequently identified. It is clear that mechanical processing has changed along history but frequently only a "microscopic" inspection can distinguish among different techniques. Some bronze samples have been collected from the Quarto d’Altino (Veneto) archaeological area in Italy (paleovenetian culture) and some model samples have been prepared by a modern artisan. The sample textures have been measured by X-ray Diffraction techniques. (111), (200) and (220) pole figures were used to calculate Orientation Distribution Functions and further recalculate pole figures and inverse pole figures. The results were compared with modern forging technology results. Textures are able to discern between hammering ancient techniques for sheet production and modern industrial rolling procedures. However, as it is demonstrated in the present work, forgery becomes difficult to detect if the goldsmith, properly warned, proceeds to erase the texture history with some hammering post-processing. The results of this contribution can offer to the archaeologists the opportunity to take into consideration the texture techniques in order to discuss the origin (culture) of the pieces and the characteristic mechanical process developed by the ancient artisan. Texture can also help the experts when discussing the originality of a certain piece keeping however in mind the cautions indicated in this publication.
Evolution of Texture in ARB Processing of Al 99.8 %
Authors: Kuśnierz Jan , Bogucka J.
Published: March 2009

The accumulative roll-bonding (ARB) process, invented a few years ago, is a
promising mode for introducing severe plastic deformation into industrial practice. The ARB process consists in rolling of the pack of two sheets up to 50 %. Then, the rolled material is sectioned into two halves, stacked and the procedure of roll-bonding is repeated. The orientation distribution of ARB processed Al 98 % up to e ~ 12 is analyzed in the paper. The evolution of crystallographic texture has been discussed in relation with changes of mechanical properties and structure.
R-Value and Texture Change of AA 1050 Al Alloy Sheet by Equal Channel Angular Pressing
Authors: Akramov Saidmurod , Lee Min Gu , Kim In Soo , Sung Dong Young , Park Byung Hyun , Kim Ingi
Published: March 2009

By severe plastic deformation of metals, an ultra fine grain size can be obtained. In the present study an AA 1050 Aluminium alloy has been severe deformed by Equal channel angular pressing (ECAP). A study on the microstructure and the texture of the samples after ECAP and subsequent heat treatment has been carried out. The specimens after ECAP showed a very fine grain size, a decrease of <100> // ND, and an increase of <111> // ND textures. The {111}<112>, {123}<634>, {110}<001>, {112}<111>, {110}<111>, and {013}<231> texture components were increased in the specimens after the ECAP and subsequent heat-treatment at 400° C for 1 hour. One of the most important properties in sheet metals is formability. The r-value or plastic strain ratio has been used as a parameter that expresses the formability of sheet metals. The change of the plastic strain ratios after the ECAP and subsequent heat-treatment conditions has been investigated and it was found that they were two times higher than those of the initial Al sheets. This could be attributed to the formation above texture components through the ECAP and subsequent heat-treatment.
Texture Gradient in ECAP Silver Measured by Synchrotron Radiation
Authors: Skrotzki Werner , Scheerbaum N. , Oertel C.G. , Brokmeier Heinz Günter , Suwas Satyam , Tóth László S.
Published: March 2009

Silver of 3N purity was deformed at room temperature by equal channel angular pressing (ECAP) using three passes of route A. The global and local texture were investigated by neutron diffraction and high-energy synchrotron radiation, respectively. The texture is characterized by typical simple shear components of fcc metals which differently deviate from their ideal positions. Local texture measurements reveal that the intensity and inclination of the texture components with respect to the extrusion direction depend on the distance from the top of the extruded bar and change from pass to pass. Reasons for the texture gradient are discussed. The texture of silver is compared with that of copper having a higher stacking fault energy.
Experiments and Modelling of ECAE Textures of f.c.c. Polycrystals
Authors: Arruffat-Massion R. , Suwas S. , Tóth László S. , Skrotzki Werner , Fundenberger Jean-Jacques , Eberhardt André
Published: March 2009

FCC metals with different stacking fault energy (SFE), namely Al, Ag and Cu have been investigated for the evolution of crystallographic texture during ECAE deformation using Route A. Different materials with different SFE result in their characteristic textures. The results have been analysed on the basis of microstructural features and related established concepts on texture evolution in FCC metals.
Evolution of Microstructure and Texture during Annealing of a Copper Processed by ECAE
Authors: Etter Anne Laure , Solas Denis , Baudin Thierry , Penelle Richard
Published: March 2009

A submicron-grained (SMG) microstructure, with an average grain size of ~0.4 µm was produced by equal channel angular extrusion (ECAE). The SMG microstructure was composed of large dynamic recrystallized grains within a matrix of deformed elongated cells. Samples were annealed for various times at 473 K and then examined using transmission electron microscopy (TEM) and electron back scattered diffraction (EBSD). The results specify that a large recovery takes place during the first annealing times. Moreover, MET investigations show nucleation of grains which orientations are found in the recrystallized texture. The EBSD measurements established that, after 7min30s at 473 K, the microstructure is equiaxed and stable with an average grain size of about 2 µm.
Reaction Stress Model and Relaxation of Reaction Stress among the Grains during Tensile Deformation of fcc Metals
Authors: Mao Wei Min , Mao W. , Yu Yong Ning
Published: March 2009

A reaction stress model is introduced in this paper and its applications for the
crystallographic texture simulation are also discussed with the comparison to the classic Taylor type model and the self consistent model. This model took the external deformation stress tensor as an initial point, and the activation process of slip systems as well as the orientation evolutions was simulated step by step. Certain relaxation of reaction stress were introduced during tensile or drawing
deformation, which predicts the tensile direction distribution along the orientation line between <111> and <100> in the inverse pole figure besides the <111> and <100> fiber texture. The simulation agrees with the common experimental observations. The model supplies a simple way to follow the deformation process in the main part of polycrystals, in which the effect of grain orientation and its interaction with the surrounding matrix are considered.
Effect Ni Addition of the Cu-Al Powder by Mechanical Alloying
Authors: Coelho Rodrigo Estevam , Veloso Ana Cris R. , Gomes Rodinei Medeiros , Melo Tadeu Antonio de Azevedo , de Lima Severino Jackson Guedes
Published: March 2009

In the present work is shown the results for solid interaction of a Cu-13.4Al-2Ni (wt%) elemental powders. Together with this mixture was placed tungsten carbide balls into a cylindrical vial under argon atmosphere. The weight ratio of the balls to powder was 20 to 1. A planetary ball mill (Fritsch Pulverizette 5) was used to perform MA at 250 rpm. The elemental powder was milled at 10min, 5 and 10 hours and a small amount of the powders were collected and analyzed via X-ray diffraction, using Cu Kα radiation (λ=0.15418 nm) and differential thermal analyses from 25 up to 450oC at a heating rate of 25oC min-1. The x-ray diffraction patterns showed that after 10h of milling the phase formation of the mechanical alloyed powders is composed of a Cu, full Cu(Al) solid solution and γAl9Cu4.
Cellular Concrete with Addition of Aluminum Recycled Foil Powders
Authors: Araújo Edval G. de , Tenório Jorge Alberto Soares
Published: March 2009

Considering its advantage of low density and favorable insulation properties, there are several applications for lightweight autoclaved aerated concrete of uniform cellular structure.The raw materials for the manufacturing of cellular concrete are Portland cement, finely grounded sand and lime. These are batched and mixed with water and metallic aluminum powder finely divided. There is a reaction between the aluminum powder and hydroxides forming millions of hydrogen bubbles throughout the mixture.The aluminum powder is the highest cost component, and the objective of this work is replacing it for another gas forming agent, like recycled foil.The foils are grinded in a high energy ball mill (attritor). Quartz sand is mixed with aluminum foil to reduce the time required for grinding, obtaining spherical particles and ensuring a uniform distribution of aluminum in the gas forming agent.The activity of this gas forming agent was determined by the gas volumetric technique. Average particle size and compressive strength of the samples were measured. The relationship between volume of the gas released during the reaction and milling conditions are presented, showing its viability for producing a high quality cellular concrete.
Microstructural Characterisation by Scanning Electron Microscopy of Spray Formed Al/SiCp Matrix Composite
Authors: Gomes E.G. , Rossi J.L.
Published: March 2009

The material used in this work was produced by spray forming AA7475 aluminium alloy and co-depositing silicon carbide particles (20% volume fraction). The spray formed composite billets were hot extruded into round bars. The microstructure was examined in the as received and heat treated (annealed, aged, and overaged) conditions by scanning electron microscopy. Scanning electron microscopy revealed an extensive Mg2Si phase precipitation at the Al/SiCp interface due probably to Mg segregation from the matrix to the interface, during the heat treatments.
Explosion Study of an Iron Powder Reduction Furnace
Authors: Brown A.E.P. , Metropolo P.L. , Carvalho Marcio A.
Published: March 2009

Explosion study in an iron powder reduction furnace was performed. Pressurized gaseous hydrogen was used as reductive atmosphere to convert iron powder in the interior of the furnace. Hydrogen was fed to the pre-chamber of the iron powder reduction furnace. The furnace was located inside a brick building. Explosion potential causes were determined by the fault tree technique. The impact effects to people, environment and materials were also analyzed by using Chem-Plus software. The consequences and vulnerability analyzes were performed considering a confined explosion inside the furnace pre-chamber, resulting from formation of a hydrogen cloud within the H2 explosion limits. The vent area criteria recommended by NFPA 68 to confined spaces were employed to the reduction furnace and to the vulnerability calculations; probit equations of the Eisenberg model were used. As results, safety measures to enhance safety on the reduction of iron powder operation inside the furnace installation were recommended.
Monofilamentary Ag/Bi:2212 Tapes – Effects of Silver Powder Addition
Authors: dos Santos Dayse Iara , Rodrigues Durval , Rubo Elisabete A. A. , Cursino Eliana
Published: March 2009

The Bi-Sr-Ca-Cu-O system has been one of the most studied superconducting ceramic materials for industry applications. The most of the studies with this aim are on silver/ceramic composites, due to the benefits and great compatibility of this metal with the oxide. Tapes made by the powder in tube (PIT) method have been successfully tested in pilot power plants in many countries but in Brazil. In this paper, 5, 10, and 20-wt% silver powders are introduced to compose the core of the tape along with the Bi:2212 ceramic powder. The results of electrical experiments are compared with those made with no silver addition Ag tapes. The best current density, at 60 K and no applied magnetic field, was found for the 10-wt% silver proportion, doubling the value obtained for the tape with no silver in the core.
The Use of Electrochemical Techniques for Ceramic Filtration Medium Cleaning
Authors: Assis Odilio B.G. , Silva Eliandro R.
Published: March 2009

Preliminary results of the use of electroomosis technique for removal of organic contaminants in ceramic filtration porous structure are presented. The method employed provokes the migration of chemical residue and waste retained or adsorbed on the pore surfaces by applying a controlled tension within an electrochemical system. Porous ceramics have been the most common filtration medium employed within a broad range of applications. Conventional cleaning of a ceramic medium is not entirely effective for organic contaminants since they cannot be excluded by size, but retained through chemical affinity to the oxide surface. Under the influence of an electrical current, adsorbed molecules underwent shear stress due to the diffuse moving layer. In their ionic state the specimens are dragged and thus move towards the opposite charged electrode. Phenol was chosen as a standard contaminant and tests carried out using commercial ceramic filtration candles. Relative contaminant concentration was assessed by optical densities (UV-Vis spectroscopy). The results show that removal is proportional for up to 58% of the contaminant in diluted condition.
Wet Processing of Triaxial Ceramics Using a Mixture Design Approach
Authors: Gomes C.M.F. , Noni A. De , Reis J.P. , Souza J.A.R. , Oliveira A.P.N. , Hotza Dachamir
Published: March 2009

An optimum amount of deflocculant was determined for three-component suspensions, based on a mixture design approach. Three raw materials were used, characterized as clay, feldspar and quartz. Ten compositions were prepared using the mixture design approach. Deflocculation curves were measured for suspensions with 40 wt.% of solids, adding sodium silicate as dispersant. The optimum deflocculant amount (ODA) was determined for each suspension, corresponding to the lowest value of apparent viscosity considering two nearest experimental points. It was observed that ODA increases linearly with the increase of the clay fraction in the mixture. A response surface and polynomial regression could be used to identify the composition range that satisfies usual conditions in wet ceramics processing.
Solid Galvanic Wastes Incorporation in Glass Matrices
Authors: Marialva-Neto A.A. , Cunha Sandra Maria , da Silva Antônio Carlos , de Mello-Castanho Sonia Regina Homem
Published: March 2009

Among the industrial solid residues, the galvanic wastes have been received special attention, due to the nature of its components. These residues in general present a high concentration of alkaline and transition metals. When discarded or stored inadequately, they can be released for the environment, causing ecological and health damages. An interesting alternative to recycle those wastes is to remove them from the environment, through its incorporation in silicate glasses matrices.
This work proposes the obtaining of amorphous structures, glasses or frits, from formulations with industrial solid galvanic wastes, with good chemical stability. A characterization study of the residue and primary materials, as commercial silica and
feldspar and investigations about the formation of amorphous phases, galvanic wastes incorporation and chemical stability of the obtained products, were made. With these results, it was possible to formulate compositions that allow the obtaining of frits for ceramic enamels, with 23 % in weight of solid galvanic waste incorporated and good coating characteristics.
Utilization of Granite Powder Waste in Ceramic Bodies for Civil Construction
Authors: Moreira J.M.S. , Freire M.N. , Holanda J.N.F.
Published: March 2009

The industry of ornamental stones processing from Espírito Santo State produces high amounts of powder waste from sawing and polishing of granite. This waste is a non-biodegradable material that when disposed generates pollution and environmental damage. Clay/waste mixtures were prepared with a kaolinitic clay and waste additions up to 10 wt.%. Various bodies were prepared by uniaxial pressing and sintered in air between 850°C and 1150°C. Emphasis is given on the drying and firing properties. The results revealed that the ceramic bodies containing granite powder waste are adequate for manufacture of structural ceramic. In addition, the employed methodology is environmentally correct and can contribute to the sustainable development.
Creep Behavior of Multi-Cation α-SiAlON Partially Stabilized Produced with an Yttrium-Rare Earth Oxide Mixture(CRE2O3)
Authors: dos Santos Claudinei , Strecker Kurt , Barboza M.J.R. , Baldacim Sandro Aparecido , Neto Francisco Piorino , Silva Olivério Moreira Macedo , Silva Cosme Roberto Moreira
Published: March 2009

a−SiAlON (a’) is a solid solution of a−Si3N4, where Si and N are substituted by Al and O, respectively. The principal stabilizers of the a’-phase are Mg, Ca, Y and rare earth cations. In this way, the possible use of the yttrium-rare earth oxide mixture, CRE2O3, produced at FAENQUIL, in obtaining these SiAlONs was investigated. Samples were sintered by hotpressing at 17500C, for 30 minutes, using a sintering pressure of 20 MPa. Creep behavior of the hot-pressed CRE-a-SiAlON/b-Si3N4 ceramic was investigated, using compressive creep tests, in air, at 1280 to 1340 0C, under stresses of 200 to 350 MPa, for 70 hours. This type of ceramic exhibited high creep and oxidation resistance. Its improved high-temperature properties are mainly due to the absence or reduced amount of intergranular phases, because of the incorporation of the metallic cations from the liquid phase formed during sintering into the Si3N4 structure, forming a a’/b composite.
Nickel Ferrite: Combustion Synthesis, Characterization and Magnetic Properties
Authors: de Melo Costa Ana Cristina Figueiredo , Gama Lucianna , Morelli M.R. , Kiminami Ruth Herta Goldsmith Aliaga
Published: March 2009

Nanosized spinel nickel ferrite particles have attracted considerable attention and efforts continue to investigate them for their technological importance to the microwave industries, high speed digital tap or disk recording, repulsive suspension for use in levitated railway systems, ferrofluids, catalysis and magnetic refrigeration systems. Nanosize nickel ferrite powders (NiFe2O4) have been prepared by combustion reaction using nitrates and urea as fuel. The resulting powders were characterized by X-ray diffraction (XRD), BET, and transmission electron microscopy (TEM). The results showed nanosize nickel ferrite powders with high specific surface area (55.21 m2/g). The powders showed extensive XRD line broadening and the crystallite size calculated from the XRD line broadening was 18.0 nm. The samples were uniaxially compacted by dry pressing, sintered at 1200°C/2h and characterized by bulk density, SEM and magnetic properties measurements. The samples showed uniform microstructures with grain size of 4.45 μm, maximum flux density of 0.18T, field coercive of the 488 A/m, and hysteresis loss of 47.58 W/kg.
Aluminas by Thermal Activation of Fibrillar Pseudoboehmite Powders
Authors: Kozievitch Valquiria F.J. , Rocha G.A. , Maia W.S. , Kiyohara Pedro K. , Coelho A.C. Vieira , Souza Santos P.
Published: March 2009

The aluminum monohydroxide pseudoboehmite is a common precursor for catalysts and ad/absorbents. Fibrillar pseudoboehmite powders were synthesized by the same preparation method from aqueous sols but aged in different times: 24, 48 and 168 hours. The sol particles were from fibrillar pseudoboehmite; the average length of the microfibrils changed sample to sample, the sizes increasing with the thermal aging time. The sols were dried by different methods: at room temperatures, forming a solid membrane; spray dried; dried at 60°C and 110°C from a gel from the sol aged 168 hours; all were fired between 200°C and 1000°C in oxidative atmosphere to produce activated transition aluminas. The phases formed was identified by XRD. The aim of the present paper is to present data showing that method of drying the sol has an effect on the temperature of formation of alpha-alumina due to the anisodiametric shape of the pseudoboehmite crystals.
Effect of High Temperature Deformation on the Hot Ductility of Nb Microalloyed Steel
Authors: Zarandi Faramarz , Yue Steve
Published: March 2009

Low hot ductility of steel at the straightening stage of the continuous casting process is a problem found in steels containing microalloying and/or certain alloying additions. The thermal schedule undergone by the billet surface in the mill has a significant effect on the hot ductility. In this work, thermomechanical processing was employed to alleviate the problem of hot ductility in the Nb-microalloyed steel. Specimens were melted in situ and subjected to the billet surface thermal schedule in order to generate a microstructure similar to that present at the straightening stage of the continuous casting process. Some deformation schedules were incorporated with the thermal schedule at very high temperatures, specifically during solidification, within the d-ferrite region, and during the d®g transformation, and the hot ductility was subsequently evaluated at the end of the thermal schedule where the straightening operation is performed. After the thermal schedule alone, the steel exhibited a very low hot ductility at the straightening stage. It was found that deformation at very high temperatures prior to the straightening stage had a considerable effect on the hot ductility, either detrimental or beneficial, depending on the region in which the deformation has been executed. The mechanisms leading to loss and improvement of hot ductility are explained in this paper.
Development of X60/X70 Line Pipe Steels through EAF-Thin Slab Casting Technology at Ezz Flat Steel, Ain Sukhna, Egypt
Authors: Megahed G.M. , Paul S.K. , El-Bitar T.A. , Ibrahim F.
Published: March 2009

API X60/X70 line pipe steels are characterized by their higher strength and excellent
toughness properties, which are achieved through grain refinement by addition of micro-alloying elements and controlled rolling. Thin slab casting of Nb micro-alloyed steel is a great challenge to the steel producer because of possible transverse cracking of slabs. The major casting parameters, which affect transverse cracking, were critically examined and modified for production of defect free slabs. The hot strip mill parameters were also designed for controlled rolling of slabs to achieve
the desired mechanical properties. Three heats (one X60 and two X70) of each 175 ton liquid steel were made and processed into 6, 8 and 10 mm hot rolled coils. In the heat of X60, Nb and Ti were used as micro-alloying elements where as vanadium was also added in X70 heats to achieve the desired strength. The YS/UTS ratio was designed to be below 0.9 by controlling the amount of Si and Mn. During slab casting, liquid core reduction (LCR) was used to reduce the slab thickness from 90 to 70 mm and to minimize the center line segregation and porosity.
The slabs were heated and homogenized in a tunnel furnace at 1150 ±10°C before rolling in the roughing mill. The rolling procedure was designed to achieve the highest possible amount of deformation at the roughing stand for best conditioning of austenite before rolling in the finishing mill. 50% and 35% reductions in slab thickness were given for rolling of 6 and 10 mm coils respectively. The final thickness reduction was then distributed over 5-6 stands of the finishing mill depending on the coil thickness. All parameters were designed to achieve finish rolling temperature 850 ±10°C in the austenite region and very near to Ar3. After rolling, the steel was fast cooled to 570±10°C before coiling. Mechanical properties and microstructure evolutions were extensively investigated. The tensile properties particularly the elongation and YS/UTS ratio achieved were good. The CVN impact
energy in transverse direction was found to be very high ranging from 220 to 330 Joules. Furthermore, the impact transition temperature (ITT) was found to be below -70 °C. The results of the drop weight tear test (DWTT) showed fully ductile behavior up to -40°C confirming the impact test results. SEM study was carried out to assess the fracture mechanism of impact-tested specimens at different temperatures.
Cr Influence on Steel Microstructure and Kinetics of Austenite Decomposition at Near-Bay Temperatures
Authors: Samoilov Andrej , Titovets Yuri , Zolotorevsky Nikolay Y. , Hribernig Gottfried , Pichler Andreas
Published: March 2009

An experimental study of Fe-C-Mn-Cr low-carbon steels with varying Cr content is
presented. Pronounced bay and a near-stasis behavior were shown in the alloy with 1.1% Cr. Isothermal transformation at temperatures roughly between 500 and 600°C reveals two pronounced stages. SEM examination of the microstructures showed that the rapid first stage is controlled by carbide-free bainite formation while the slow second stage is controlled by a eutectoid-type reaction. Some microstructure features of the transformation were noted and discussed. Based on
experimental observations, a model of austenite decomposition was developed to account for the main features of transformation kinetics in the alloys with varying Cr content.
Microstructure Evolution in Fine-Grained Microalloyed Steels
Authors: Lottey K.R. , Militzer Matthias
Published: March 2009

There is an increasing emphasis to develop novel hot-rolled high strength steels with
fine and ultra fine grain sizes for structural and other applications. Traditionally the concept of microalloying has been employed to refine microstructures thereby obtaining increased strength levels. For example, employing an alloying strategy with Nb, Ti and Mo is promising to attain yield strength levels of 700MPa and beyond. In the present study, the transformation behaviour is investigated for a HSLA steel containing 0.05wt%C-1.65wt%Mn-0.20wt%Mo-0.07wt%Nb- 0.02wt%Ti. The ferrite formation from work-hardened austenite has been studied for simulated
run-out table cooling conditions employing a Gleeble 3500 thermomechanical simulator equipped with a dilatometer. The effects of cooling rate and initial austenite microstructure, i.e. austenite grain size and degree of work hardening, on the austenite decomposition kinetics and resulting ferrite grain size have been quantified. Based on the experimental results, a phenomenological transformation and ferrite grain size model is proposed for run-out table cooling conditions. The
transformation model includes submodels for transformation start and ferrite growth. The latter is described using a Johnson-Mehl-Avrami-Kolmogorov approach. The degree of work hardening is incorporated by introducing an effective austenite grain size as a function of the strain applied under no-recrystallization condition. The ferrite grain size can be predicted as a function of the transformation start temperature. Increasing both cooling rate and amount of work hardening can optimize ferrite grain refinement. In the present steel, ferrite grain sizes of as low as 2µm have been obtained in this way. The results observed for the present steel are compared to the transformation behaviour in previously studied Nb-Ti HSLA steels of similar strength levels.