Influence Of Processing Route Research Articles

The effect of dual thermomechanical processing paths on resulting microstructure and quasi-static mechanical properties of Mg-1Zn-0.2Ca

In this work, cast Mg-1Zn-0.2Ca (wt%) was thermomechanically processed using a two-step procedure to identify the impact of both processing steps on the resulting microstructure and mechanical properties. Samples were first preprocessed via rolling or conventional extrusion (at 400 °C), followed by Equal Channel Angular Extrusion (ECAE), utilizing routes A or Bc. ECAE was performed at 300 °C for the first pass, followed by 275 °C, 250 °C, and 225 °C for passes 2–4. Subsequent microstructures, textures, and quasi-static tension test results are presented to illuminate the effect of preprocessing and ECAE route on grain size refinement and mechanical behavior. Preprocessing via rolling yielded a smaller, more homogeneous initial grain size than the conventionally extruded material. After the second processing step, ECAE, the microstructural differences due to the preprocessing methods are reduced, but not eliminated, and mechanical properties show little variation between rolling and extrusion. The ECAE route did not impact the microstructural refinement, however, the 4Bc route did lead to enhanced ductility (>36%) and higher average ultimate tensile strengths, compared to the 4A route, when tested in the normal direction (perpendicular to the ECAE extrusion direction). The relative importance of texture alteration versus grain refinement and homogeneity is highlighted herein. Lastly, we comment on the influence of processing routes on inclusions and voids.

Influence of Processing Route on the Fracture Resistance of Equal Channel Angular Pressing Deformed Iron

The mechanical behavior of pure iron (Armco‐iron) deformed at 200 °C by equal angular channel pressing using processing route BC is investigated with a focus on the fracture properties. In particular, the fracture toughness in terms of elastic–plastic fracture mechanics is evaluated for different specimen orientations with respect to the last deformation step. In addition, the results are comprehensively compared with material processed by route A. The microstructural features of both deformation routes are presented and the underlying microstructure–property relationships are discussed. Both deformation routes (A and BC) lead to a comparable strength even though the microstructural features differ. Route A contains a banded and well‐aligned structure almost parallel to the extrusion direction. For route BC, the microstructural alignment is rotated with respect to the pre‐crack orientation and the grain structure is more heterogeneous. For both deformation routes, the crack plane orientation plays a significant role in the fracture characteristics. The fracture toughness along the extrusion direction, with substantially low fracture toughness for route A, is markedly enhanced for route BC. Consequently, route BC offers a pathway to obtaining severe plastic deformation (SPD) materials with high damage tolerance and a considerably lower extent of anisotropy.

Influence of processing route on microstructure and properties of Al13.45FeCrNiCo high entropy alloys

The Al13.45FeCrNiCo high entropy alloys (HEAs) were obtained using two different processing routes, namely (i) mechanical alloying (MA) and spark plasma sintering (SPS), and (ii) vacuum induction melting – copper cast molding. A final homogenizing treatment step was applied to the as synthesized materials. Based on thermodynamic and empirical criteria for phase formation, the alloy was designed to develop a mixture of the face-centered-cubic (FCC) and body-centered-cubic (BCC) solid solution. The contribution of aluminum content on the alloy microstructure in terms of hardening of solid solution and precipitation hardening was highlighted. The influence of the processing route on the microstructure evolution and the relationship between the microstructure and properties of HEA materials were established by performing X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), and high-resolution (HR) TEM analyses, as well as microindentation and compression tests. The powder metallurgy processes produced a two-phase structure consisting of at least two types of crystalline grains based on FCC and BCC solid solutions. Increasing the sintering temperature from 950 °C to 1050 °C contributed to structural changes in the materials. Lower sintering temperatures (950 °C and 1000 °C) generated a single FCC phase structure, while at 1050 °C two FCC and BCC phases were obtained without any evidence of the liquid phase sintering. The as cast route generated a hypoeutectic type structure with a very fine and preferentially oriented dendritic structure, in which the interdendritic space is occupied by a second phase arranged in a network where the microstructure appears to be the result of a eutectic transformation with precipitation of secondary phases rich in Ni and Al. All the synthesized alloys revealed high hardness and a good mechanical behavior in compression. Sintered HEA materials exhibited higher Vickers hardness than as cast HEA, even after the heat treatment process, while the as cast HEA material has better ultimate strength and deformation behavior than sintered HEAs. The processing route did not affect the nature of the FCC and BCC solid solution phases formed in the Al13.45FeCrNiCo HEA materials but was responsible for the variation of phase proportion in the HEA’s microstructure, which in turn influenced the mechanical properties.

The influence of the processing route on the fragmentation of (Nb,Ti)C stringers and its role on mechanical properties and hydrogen embrittlement of nickel based alloy 718

The nickel-base superalloy 718 is a precipitation hardened alloy widely used in the nuclear fuel assembly of pressurized water reactors (PWR). However, the alloy can experience failure due to hydrogen embrittlement (HE). The processing route can influence the microstructure of the material and, therefore, the HE degree. In particular, the size and distribution of the (Nb,Ti)C particles can be affected by the processing. In this regard, the objective of this work was to analyze the influence of cold and hot deformation processing routes on the development of the microstructure, and the consequences on mechanical properties and hydrogen embrittlement. Tensile samples were hydrogenated through gaseous charging and compared to non-hydrogenated samples. Characterization was performed via scanning and transmission electron microscopies, as well as electron backscattered diffraction. The processing was effective to promote significant variations in average grain size and length fraction of special Σ3n boundaries, as well as reduction of average (Nb,Ti)C particle size, being these changes more intense for the cold-rolled route. For the mechanical properties, on one side, the cold-rolled route presented the highest increase in ductility for non-hydrogenated samples, while, on the other side, had the highest degree of embrittlement under hydrogen. This dual behavior was attributed to the interaction of hydrogen with the (Nb,Ti)C particles and stringers and its ensuing influence on the fracture processes.

Influence of processing route on bonding of AA6082 and MgAZ31B by severe plastic deformation process

Equal channel angular pressing (ECAP), is a proven manufacturing technique that produces ultrafine-grained structure (UFG) accompanied by various property enhancements of the material such as coherent interface and high shear bonding. The exceptional feature that separates this process with other joining processes is the advantage of having isotropic microstructural grain distribution along with the joining layer of the two dissimilar metals, with that as a motive the focus was given to the bonding of MgAZ31B and AA6082 through ECAP but the process failed to meet the expected objectives. The reasons for failure were analyzed and recorded that the difference in material ductility caused the bonding failure of the two dissimilar metals. The second part of the article deals with the severe plastic deformation of Al 6061 as the ECAP specimen based on its mechanical properties and applications in industries. Al 6061 samples were processed up to two passes of ECAP in an acute angle die and were characterized. Route B produced maximum strength enhancement compared to Route A. Microstructural investigation was carried out to identify the reason for the difference in the results of both the routes.

Influence of Processing Route and Chemical Composition on Electrochemical Properties of High-Capacity Layered Oxide Cathodes

To obtain high-capacity Li ion batteries; oxide cathodes with layered structure still remain the ones that provide high enough capacities. It is known that electrons and Li+ ions are being extracted simultaneously in the charging process. During high-voltage charging, more ionic/electronic defects formed in layered oxides will be created. Thus, their electrochemical and structural properties are strongly affected by the formation and/or elimination of these defects. Higher defect concentration, like Li vacancies, VLi’, tends to destabilize its crystal structure. As a result, the phase transformation may occur in the cycled cathode. Accordingly, the capacity fading was frequently observed in cycled layered cathode due to the phase-changing process. Moreover, the existing defects in layered oxides are typically determined by the condition of fabrication processes, for instance the dopants and oxygen partial pressure.In this study, two well-known layered oxides with fixed 80% Ni in the transition metal ion layer, namely NMC 811 and LiNi0.8Co0.15Al0.05O2 (NCA), were investigated. Their minor elements/dopants Mn and Al may play an important role on affecting their defect chemistry as well as electrochemical properties. Thus, their electrical/electrochemical/structural properties are examined as a function of the minor dopants, Mn and Al. First, the electrical measurement of NMC 811 and LiNi0.8Co0.15Al0.05O2 are conducted. Assembled cells using above-mentioned cathode and Li anode with desired liquid electrolyte were tested and cycled. SEM and XRD analyses were conducted on assembled and cycled cells. The analysis and results are illustrated based on the chemical characteristics of doping ions and the electronic/ionic defects induced.

WITHDRAWN: Influence of processing routes on the creep deformation and damage evolution of Zr-2.5Nb alloy

Abstract Tensile creep behavior of the Zr-2.5Nb alloy tubes having outer diameters of 90 mm and 110 mm, processed by extrusion and forging, respectively has been studied in the temperature range of 350-450°C under the stress range of 82-319 MPa. The creep curves have shown that the minimum creep rate and time to rupture changes with the applied stress and temperature. The apparent activation energy of creep ( Q C ) values, have been determined by using the power law for 90 mm and 110 mm tube samples are found to be ∼ 231 kJ/mol and ∼ 264 kJ/mol respectively, which is significantly higher than that for lattice self-diffusion of Zr (113 kJ/mol). The microstructural examination of the creep-ruptured samples through transmission electron microscopy (TEM) has shown evidence for multiplication of dislocations, along with their interaction with the β-(Nb, Zr) precipitates in the α-Zr matrix, which is mainly contributed to origin of threshold stress during creep. By incorporating the threshold stress data in the modified power-law relation, the true activation energy of creep ( Q t ) values from the samples of 90 mm and 110 mm tubes are found as 118 kJ/mol and 132 kJ/mol, respectively, which are close to that for lattice self-diffusion in Zr. The obtained true stress exponent ( n t ) values of 3.6 and 4.9 and formation of dislocations sub-grains in the power-law regime of steady state creep, which suggests that the dislocation climb is the rate-controlling mechanism. Further, creep data of the alloy are validated by the Monkman-Grant and Modified Monkman-Grant relationship, and time to rupture effectively predicted using the Larson-Miller Parameter. The creep damage tolerance factors are in the range of 1.5-2.5 for the tubes suggest cavity growth mechanism. Additionally, the comparison of creep data with the Ashby-Dyson maps indicates early formation of cavities due to creep.

Influence of processing route on the alloying behavior, microstructural evolution and thermal stability of CrMoNbTiW refractory high-entropy alloy

Abstract

Influence of processing route on microstructure and wear resistance of fly ash reinforced AZ31 magnesium matrix composites

Abstract Utilizing fly ash (FA) as reinforcement for magnesium matrix composites (MMCs) brings down the production cost and the land pollution. Magnesium alloy AZ31 was reinforced with FA particles (10 vol.%) successfully by two different processing methods namely conventional stir casting and friction stir processing (FSP). The microstructural features were observed using optical microscope, scanning electron microscope and electron backscatter diffraction. The sliding wear behavior was tested using a pin-on-disc wear apparatus. The stir cast composite showed inhomogeneous particle dispersion and coarse grain structure. Some of the FA particles decomposed and reacted with the matrix alloy to produce undesirable compounds. Conversely, FSP composite showed superior particle dispersion and fine, equiaxed grains by dynamic recrystallization. FA particles encountered disintegration but there was no interfacial reaction. FSP composite demonstrated higher strengthening and wear resistance to that of stir cast composite. The morphology of the worn surface and the wear debris were studied in detail.

Lexical and semantic connections in number words translation

The present study investigated the influence of lexical links and conceptual mediation in number word translation. In four experiments, a semantic blocking paradigm was used with numerical stimuli and stimuli from other non-number categories. The performance of Spanish L1–English L2 bilinguals was examined in backward and forward translation (Experiment 1 and 3), in naming Arabic digits and pictures (Experiment 2A) and in reading L1 and L2 words (Experiment 2B). The blocked context produced a facilitatory effect for numerical stimuli in the lower range. This result contrasts with the interference effect observed for stimuli from non-number categories in translation and naming tasks. These results are interpreted to mean that the translation of number words, particularly those in the lower range of the numeric sequence, takes place with a large influence of the lexical connections. It supports the suggestions that the influence of processing routes depends on the type of items.

Influence of processing routes on morphology and low strain stiffness of polymer/nanofibrillated cellulose composites

The morphology of polymer/nanofibrillated cellulose (NFC) composite sheets produced using different techniques and its influence on low strain stiffness were assessed by optical and transmission electron microscopy. Solvent processing led to relatively homogeneous NFC dispersions and significant reinforcement of the in-plane Young’s modulus. The continuous cellular networks obtained by wet comingling of polylactide powder or latex with NFC also provided efficient and essentially scale independent reinforcement, in spite of the extensive agglomeration of the NFC. However, the irreversible nature of these networks is incompatible with low pressure thermoplastic processing routes such as physical foaming, and while they may be broken up by e.g. extrusion, this led to substantial loss in reinforcement, particularly at temperatures above the glass transition temperature of the matrix, consistent with the observation of isolated low aspect ratio NFC aggregates in the extruded specimens.

Influence of processing route on electrical properties of Bi4Ti3O12 ceramics obtained by tape-casting technology

Bismuth titanate powders (Bi4Ti3O12-BIT) were fabricated by solid state reaction (SSR) and polymeric precursor method (PPM). From these powders, Bi4Ti3O12 pellets were obtained by tape-casting using plate-like templates particles prepared by a molten salt method. The BIT phase crystallizes in an orthorhombic structure type with space group Fmmm. Agglomeration of the particles, which affects the densification of the ceramic, electrical conduction and leakage current at high electric fields, was monitored by transmission electronic microscopy (TEM) analyses. FEG-SEM indicated that different shape of grains of BIT ceramics was influenced by the processing route. Both SSR and PPM methods lead to unsaturated P–E loops of BIT ceramics originating from the highly c-axis orientation and high conductivity which was affected by charge carriers flowing normally to the grain boundary of the crystal lattice.

Investigation of Tensile Property and Pore Closure Behavior and the Influence of Processing Route during Equal Channel Angular Pressing of Pure Aluminum Powder Compacts

This paper revolves around the idea of finding the strength enhancement of pure ‘Al’ compacts processed through Equal-Channel Angular Pressing (ECAP) process which ultimately results in fine grain structure of the material processed. The material initially prepared through conventional powder metallurgical route is processed in an ECAP die with a channel angle of 1100. The tensile test and micro-structural evaluation is done following the ECAP process and it is found that there was a substantial enhancement in the tensile properties and Ultrafine Grain (UFG) structure is obtained due to the Severe Plastic Deformation (SPD) phenomenon taking place during the process. The pore closure behavior is also analyzed using the TEM micrographs after each pass in ECAP die and promising results are obtained when the material is processed through different routes. The dislocation cell structure is also found to get refined after each pass through the die. The pore closure behavior is also confirmed using the DEFORM 3D software when the aluminum is simulated under similar conditions.

Influence of Processing Route on the Work-Hardening and Ductile Fracture of an AA6060 Aluminium Alloy

Tensile tests on smooth and notched axisymmetric specimens were carried out to determine the large strain work-hardening curves and the ductile fracture characteristics of an AA6060 aluminium alloy for three different processing routes. The alloy was processed in three subsequent steps: 1) casting and homogenization, 2) extrusion, and 3) cold rolling and heat treatment to obtain a recrystallized grain structure. After each processing step, the material was tested after natural ageing for more than one week. A laser-based extensometer was used to continuously measure the average true strains to failure in the minimum cross-section of the specimens and the true stress-strain curves were calculated. Since these curves are influenced by necking, they do not represent the correct work-hardening of the material. Accordingly, finite element (FE) simulations of the tensile tests on the smooth axisymmetric specimens were conducted to determine the work-hardening curves to failure, using an optimization tool that interfaced with the nonlinear FE code and the experimental stress-strain curves as objectives. The microstructure of the alloy was characterized after the three processing steps by optical and scanning electron microscopy, and fractography was used to investigate the failure mechanisms.

Influence of processing route and section size on tensile stress–strain and work hardening behaviour of 9Cr–1Mo ferritic steel

True stress–true plastic strain behaviour of 9Cr–1Mo steel in two different product forms, i.e. 20-mm plate and thick section tubeplate forging has been examined in the temperature range 300–873 K in the framework of various flow relationships. The analysis suggested that a combination of Ludwigson and Hollomon equations describes stress–strain behaviour most accurately in both plate and tubeplate forging. Two-stage work hardening has been observed in the variations of instantaneous work hardening rate with stress. The variations in stress–strain, flow parameters and work hardening rate as a function of stress with respect to temperature exhibited three distinct temperature regimes. Signatures of dynamic strain ageing at intermediate temperatures and dominance of dynamic recovery at high temperatures have been observed. The differences in tensile flow and work hardening behaviour obtained between plate and tubeplate forging has been attributed to the affects associated with the initial microstructures obtained for the two product forms in 9Cr–1Mo steel.

Influence of processing route and section size on tensile stress–strain and work hardening behaviour of 9Cr–1Mo ferritic steel

True stress–true plastic strain behaviour of 9Cr–1Mo steel in two different product forms, i.e. 20-mm plate and thick section tubeplate forging has been examined in the temperature range 300–873 K in the framework of various flow relationships. The analysis suggested that a combination of Ludwigson and Hollomon equations describes stress–strain behaviour most accurately in both plate and tubeplate forging. Two-stage work hardening has been observed in the variations of instantaneous work hardening rate with stress. The variations in stress–strain, flow parameters and work hardening rate as a function of stress with respect to temperature exhibited three distinct temperature regimes. Signatures of dynamic strain ageing at intermediate temperatures and dominance of dynamic recovery at high temperatures have been observed. The differences in tensile flow and work hardening behaviour obtained between plate and tubeplate forging has been attributed to the affects associated with the initial microstructures obtained for the two product forms in 9Cr–1Mo steel.

Influence of processing route and yttria additions on the oxidation behavior of tungsten

The oxidation resistance in dry air of pure tungsten and tungsten reinforced with a dispersion of 0.6wt.% Y2O3 nanoparticles has been evaluated between 873 and 1073K, temperature range that divertor in fusion power plants should endure during long-term times in the case of loss of coolant accident and/or air ingress in the vessel. Both materials were prepared by a powder metallurgy route involving hot isostatic pressing of ball milled tungsten powders and tungsten with dispersed Y2O3 nanoparticles. The results have been compared with those of pure tungsten processed by conventional techniques. Thermogravimetric tests at 873K revealed that the processing route as well as yttria addition considerably affected the oxidation resistance of pure tungsten. Mass gain of W–0.6Y2O3 at 873K was five and two times lower than that of pure tungsten prepared by conventional processing techniques and by powder metallurgy, respectively. This different behavior was related to changes in the structure and composition of the oxide scale. Above 873K, the kinetics were significantly accelerated for all materials due to the development of a non-protective oxide scale from the earliest oxidation stages, although the kinetics of Y2O3-containing material were still the slowest, specially at 973K. It was analyzed how yttria additions modify the oxidation mechanism of tungsten.

The influence of processing route on the structuring and properties of high‐density polyethylene (HDPE)/clay nanocomposites

AbstractThe effect of different processing routes on structure and properties of high‐density polyethylene (HDPE)‐clay nanocomposites was assessed. Different compatibilizer/clay ratios (α) were also studied to determine if interactions exist between processing route and polymer‐clay compatibility. HDPE/HDPE‐g‐MA/clay with α values of 1 to 4 were melt compounded (twin screw extrusion), and then processed via three routes: compression moulding, compression moulding followed by biaxial stretching or blown film extrusion. The structure was examined using X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Tensile and oxygen barrier properties were determined. It was found that biaxial extensional forming produced the best enhancement in properties. An interaction between processing route and polymer‐clay compatibility is evident. Halpin‐Tsai (H‐T) model was employed to predict relative modulus values. It showed good agreement with the experimental data. For biaxial extension at α = 4.0, the experimental relative modulus is greater than the predicted value. This may indicate the existence of a “nano” effect at the polymer‐clay interface. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers

Influence of Processing Route and Section Size on Elevated Temperature Tensile Properties of 9Cr-1Mo Ferritic Steel

AbstractTensile tests were performed on specimens obtained from 20 mm plate in normalised and tempered condition and quenched and tempered thick section tubeplate forging to assess the influence of processing route and section size on room and elevated temperatures (300–873 K) tensile properties of 9Cr-1Mo ferritic steel. Yield and ultimate tensile strength values of plate and tubeplate forging exhibited a gradual decrease up to intermediate temperatures followed by a rapid decrease at high temperatures. Ductility values displayed a gradual decrease to a minimum at intermediate temperatures followed by an increase at high temperatures. The fracture mode remained transgranular. At intermediate temperatures, 9Cr-1Mo steel in both the product forms exhibited similar serrated flow, an important manifestation of dynamic strain ageing. At all temperatures, thick section tubeplate forging exhibited lower strength and higher ductility values compared to normalised and tempered steel. The inferior strength values were attributed to coarse microstructure of the forging.

Influence of processing route on microstructure and mechanical properties of two Mg–Ni–Y–RE alloys

The effect of the processing route on the microstructure and mechanical properties of two Mg–Ni–Y–CeMM alloys has been evaluated. The alloys processed by a powder metallurgy route presented higher strength, thanks to the finer grain size and more homogeneous dispersion of second-phase particles. In the alloys prepared by hot extrusion of as-cast rods, hardening induced by coarse second-phase particles was higher due to load transfer from the magnesium matrix towards the particles. Irrespective of the processing route, the absence of decohesion between the different interfaces in the Mg–Ni–Y–CeMM alloys evidenced their inherent strong nature.