Methods Of Thermomechanical Treatment Research Articles

Optimizing multi-recycled concrete for sustainability: Aggregate gradation, surface treatment methods and life cycle impact assessment

Utilizing demolished waste as recycled aggregate in concrete is a sustainable practice, however, the concerns over inconsistent quality, such as hardened mortar content and water absorption, hinder global adoption. This study evaluates the physical, microstructural properties and gives insights into Life Cycle Impact Assessment of three generations of recycled aggregate concrete. The microstructure analysis yielded compelling insights into the role of Interfacial Transition Zone (ITZ) of reclaimed aggregate on concrete. The study demonstrated that the effective proportioning of coarse and fine aggregate particles using Compressible Packing Model (CPM), resulted in a reduction of dosage of cement in concrete volume, reducing the Binder Intensity Index (BII), and an improvement in the strength and stability of concrete. Additionally, surface treatment methods, including water soaking, mechanical, and thermo-mechanical treatments, were explored. The thermo-mechanical treatment method proved to be effective in reducing 40–60 % of residual mortar. Life cycle assessment of treated and untreated recycled aggregate concrete was performed, considering five environmental impact indicators viz., Global Warming Potential (GWP), Acidification Potential (AP), Eutrophication Potential (EP), Abiotic Depletion Potential (ADP) and Human Toxicity (HT). These indicators illustrated that CPM method of mix proportioning accompanied with thermo-mechanical treatment of repurposed aggregate resulted in lowering environmental impact. These findings underscore the potential for sustainable concrete construction through the use of treated recycled aggregate, offering valuable insights into methods for augmenting its quality and performance.

Composition and Textural Characteristics of Char Powders Produced by Thermomechanical Processing of Sunflower Seed Husks

The paper presents the results of experimental studies on the production of fine char powder from sunflower seed husks by a novel method of thermomechanical treatment with pulsed shock waves and supersonic jets of the mixture of ultra-superheated (above 2000 °C) steam and carbon dioxide, as well as the results of examination of the produced char powder in terms of its chemical, phase, and granulometric composition and structural, morphological, and texture characteristics. The objective of the research is to explore the possibility of using the resulting char powder as a sorption-active material for organic substances. It is shown that the obtained char particles and their agglomerates have an average size of 20–30 nm and 12–24 µm, respectively, have the shape of disks and ellipsoids, consist mainly of amorphous carbon (up to 56 wt%) and oxygen (up to 42 wt%), and have a specific surface area of 1.1–1.7 m2/g. It is concluded that such a char powder can be used as an absorbent for organic substances when dried and deagglomerated.

Количественный анализ текстуры деформации и первичной рекристаллизации при угловой прокатке и отжиге магнитострикционного сплава (Fe83Ga17)99B1

The Fe–Ga alloy is a promising magnetostrictive material thanks to of the optimal combination of functional properties and relatively low price due to the absence of rare-earth elements in the composition. To obtain the maximum magnetostriction in Fe–Ga polycrystals, it is necessary to create a crystallographic texture with a predominance of the <100> direction, since the tetragonal magnetostriction constant is the largest. Traditional methods of thermomechanical treatment do not lead to the formation of such a texture in a bcc alloy. In this paper, for the first time, the authors propose to use inclined rolling to increase the proportion of favorable texture components. Warm rolling with a deformation degree of 70 % was carried out at angles of 0, 30 and 90° to the direction of hot rolling. The deformation texture was examined using X-ray texture analysis and the texture and structure of the material after recrystallization was analyzed by electron backscatter diffraction (EBSD) on a scanning electron microscope. Quantitative texture analysis was carried out using the orientation distribution function (ODF) method using the ATEX software. The volume fraction of some texture components was calculated. The study shows that a significant change in the deformation textures and primary recrystallization occurs during rolling at an angle of 90°. The sample after such rolling contains the largest amount of the planar component {100}. The study identified a relationship between the texture of deformation and recrystallization in Fe–Ga: to increase the proportion of components with the <001> crystallographic direction during recrystallization, the presence of planar components {111} in the deformation texture is necessary, which is associated with the predominant growth of favorable components in the deformation matrix with such a texture.

Evolution of the grain structure of metals and alloys under intense plastic deformation: multilevel models

It is well known that the performance properties of products made of metals and alloys are determined mainly by the meso- and microstructure of the latter. The structure of materials is formed and undergoes significant changes in the processes of manufacturing parts and structures using thermomechanical processing methods. A very important parameter that determines the physical and mechanical characteristics of materials is the grain structure (size, shape, relative positions of grains and inclusions of various phases). In recent decades, in this regard, special attention has been paid to the processes of severe plastic deformation (SPD), which make it possible to obtain a submicro- and nanocrystalline grain structure, which provides a significant increase in the performance properties of products made of metals and alloys. The development of SPD technologies in modern conditions is unthinkable without mathematical modeling of the processes under consideration; the most important component in the development of such a "toolkit" are constitutive relations (or, more broadly, constitutive models). In connection with the foregoing, the latter should be able to describe the evolutionary structure at various scale levels. Until now, the practice of developers of materials processing technologies has been dominated by the use of macrophenomenological models based on classical continuum theories of plasticity, viscoplasticity, and creep. From the second half of the 20th century to the present, various improvements to the constitutive models of the above class have been proposed, in which additional parameters and kinetic equations are introduced for them, describing certain characteristics of the structure of materials. As a rule, such models make it possible to obtain an adequate picture of the changing structure, however, for specific materials and methods of thermomechanical treatment. At the same time, such models, unfortunately, do not have the necessary universality; when changing the material or processing method, they have to be significantly “customized” to specific conditions, up to a complete change in the relationships included in the model. A brief review of works devoted to the creation and application of models of this class is given in the previous article by the authors. The most promising and possessing a significant degree of universality, according to the authors, are currently multilevel constitutive models based on the introduction of internal variables and physical theories of plasticity (elastoviscoplasticity). A review of works that consider various aspects of the formulation, modification, numerical implementation and application of such models is proposed in this article. The main attention is paid to models focused on the description of changes in the structure of materials due to dislocation-disclination mechanisms; a brief note is given on models that take into account thermally activated diffusion mechanisms, due to which the processes of recovery and recrystallization are realized.

Simultaneous increase of ultimate tensile strength and uniform elongation of 30Si2MnCrMoVE ultra-high strength steel by hot deformation direct quenching and partitioning

In order to further improve the combination of strength and ductility for 30Si2MnCrMoVE ultra-high strength steel (UHSS), a thermomechanical treatment, named deformation direct quenching and partitioning (DQ&P), was carried out on it. The microstructure evolutions and mechanical properties of 30Si2MnCrMoVE UHSS treated by DQ&P were compared with those treated by conventional off-line quenching and tempering (Q&T) through various microscopic characterization methods and uniaxial tensile tests. Moreover, the effects of austempering temperature on the microstructure evolutions and mechanical properties of the studied steel after DQ&P process were also investigated. The results show that the DQ&P samples, although lower or slightly lower yield strength, possess significantly higher ultimate tensile strength due to higher work-hardening rate caused by high density dislocations and fine dispersed carbides. Moreover, DQ&P310 sample exhibit apparently higher uniform elongation than Q&T sample despite of comparable content of retained austenite due to more prone to transformation induced plasticity (TRIP) effect. The DQ&P process can increase the ultimate tensile strength by 267 MPã423 MPa and the uniform elongation by 78%∼85%, respectively, as compared to Q&T process, which indicates that DQ&P process may be a promising thermomechanical treatment method to improve the comprehensive mechanical properties of the studied steel. The strengths and elongations of DQ&P samples do not vary monotonously with the increase of austempering temperature, which are both closely related to the content of retained austenite.

Impact of Instant Controlled Pressure Drop (DIC) Treatment on Chemical, Functional and Immunological Properties of Wheat Gluten

Instant controlled pressure drop DIC technology is a thermo-mechanical treatment method that combines both mechanical and heat impacts of saturated steam pressure over a short period of time. This study aims to investigate the effect of DIC (100–165 °C for 20–60 s) on chemical, functional and immunological properties of wheat gluten powder using response surface methodology. Chemical properties were studied by Fourier transform infrared spectroscopy, thiol measurement and gel electrophoresis. Protein solubility, emulsifying capacity and foaming ability were evaluated as functional properties. Immunological properties were studied by indirect ELISA. After DIC treatment, wheat gluten became rigid which was due to a significant increase in β-structures. Significant loss of α-helixes and a significant increase in intermolecular β-sheet and the rearrangement of disulfide bonds indicated the denaturation of wheat gluten protein. However, the primary structure was not affected. DIC treatment altered the functional properties. The lowest protein solubility, emulsifying capacity and foaming ability were obtained at the highest DIC treatment conditions (165 °C, 60 s). The immunoreactivity of celiac IgA antigliadin antibodies of DIC wheat gluten depended on the individual patient characteristics. However, we note that the immunoreactivity has increased overall.

Effect of boron microaddition on hardenability of new-developed HSLA-type steels

Purpose: The paper presents the results of investigations on the effect of 0.003% boron microaddition on the hardenability of new-developed HSLA-type steels. In order to prevent the binding of the boron microaddition with nitrogen in BN nitrides, Ti microaddition at concentrations of 0.033% and 0.028% was also added into the tested steels. Design/methodology/approach: Evaluation of hardenability of the investigated steels was carried out on the basis of the Jominy test and the analytical method, according to the ASTM 255-89 standard, taking into account the effect of the boron microaddition. Additionally, developed of the CCT-diagram of investigated steel. A DIL 805A/D dilatometer with a LVDT-type measuring head was used to carry out the dilatometric test. Findings: Microaddition of boron, introduced into steel in a concentration of 0.003% along with Ti microaddition shielding (in concentration of 0.033% in steel A and 0.028% in steel B), advantageously improves hardenability. This is reflected in calculated ideal critical diameter DIB, which is equal 163 mm for steel A and 155 mm for steel B. The form of curves of phase transformations of supercooled austenite is typical for steels with microaddition of boron, with similar chemical composition. Research limitations/implications: Due to similar chemical composition of investigated steels, the kinetics of phase transformations of austenite, supercooled under continuous cooling, was determined for steel B containing 0.28% C, 1.4% Mn, 0.3% Si, 0.26% Cr, 0.22% Mo and Nb, Ti, V and B microadditions at 0.027%, 0.028%, 0.019% and 0.003% respectively. Practical implications: Tested steels have high hardenability and show the full usability for production of forged parts with the method of thermomechanical treatment, i.e., hot- deformed in the temperature range adjusted to the type of microadditions added to steel, with direct quenching of forgings from finishing forging temperature. The results of the tests may be useful for developing the parameters of heat treatment and thermomechanical treatment of investigated steels. Originality/value: The hardenability of new-developed HSLA-type steels was determined.

Effect of thermomechanical treatment on wear resistance of Hadfield’s steel

The technique of thermomechanical treatment of high manganese steel under high-temperature plastic deformation of cylindrical specimens with various degrees of reduction is presented. The experimental data on the wear of samples on granite and electrocorundum show that the use of the thermomechanical treatment method can significantly increase the abrasive wear resistance of high manganese steel by up to 50%, and the method itself can be recommended for the introduction into the technology of manufacturing wear parts of ore mining and processing equipment in order to increase their service life.

Unconventional Methods of Thermomechanical Treatment of Tool Steel

Tool steels are traditional materials whose heat treatment routes are well-established. Despite that fact, unconventional treatment methods can be used, for instance for refining chromium carbides and general strengthening of the structure. One of the methods that considerably alter microstructure is semi-solid processing. By means of passing through the semi-solid state, the X210Cr12 steel (CSN 19436) developed a microstructure of polyhedral austenite grains embedded in a carbide network. Forming of this material at an appropriate temperature led to recrystallization of the austenitic microstructure and to uniform distribution of carbides with a size of approximately 2 μm. By varying the rate of subsequent cooling, microstructures ranging from austenite to martensite could be obtained.

Effect of Thermomechanical Processing on the Microstructure and Mechanical Properties of Nb-Ti-V Microalloyed Steel

The paper presents the results of thermomechanical treatment via forging on the microstructure and mechanical properties of newly obtained microalloyed steel containing 0.28% C, 1.41% Mn, 0.027% Nb, 0.028% Ti, and 0.019% V. The investigated steel is assigned to the production of forged elements for the automotive industry. Conditions of forging using the thermomechanical processing method were developed based on plastometric tests. Continuous and double-hit compression tests were conducted using the Gleeble 3800 thermomechanical simulator. The samples were investigated in a temperature range from 900 to 1100 °C and a strain rate of 1 and 10 s−1. To determine the recrystallization kinetics of plastically deformed austenite, discontinuous compression tests of samples using the applied deformation were conducted in a temperature range from 900 to 1100 °C with isothermal holding of the specimens between successive deformations for 2-100 s. Observations of the microstructures of thin foils were conducted using a TITAN80-300 FEI transmission electron microscope. The applied thermomechanical treatment allows to obtain a fine-grained microstructure of the austenite during hot-working and production of forged parts. These acquire advantageous mechanical properties and guaranteed crack resistance after controlled cooling from the end plastic deformation temperature and successive tempering. Forgings produced using the thermomechanical treatment method, consecutively subjected to tempering in a temperature range from 550 to 650 °C, reveal values of YS0.2 which equal from 994 to 892 MPa, UTS from 1084 to 958 MPa, KV from 69 to 109 J, KV−40 from 55 to 83 J, and a hardness ranging from 360 to 300 HBW.

Structural and Technology Support Quality Improvement of Gear Coupling

In this work the question of sharing use a thermo-mechanical treatment method and forming spatial tool based on a kinematic method researches gearings, is considered. Also, the method of thermo mechanical treatment a gear couplings teeth, with the receiving a spatial teeth geometry and ensuring required physical- mechanical properties of them, is presented. For implementation of this method, the scheme of the device and the special tool is developed, which allows to fair blanking of spatially modified teeth. The design procedure a teeth tool’s geometric parameters of the line addendum modification are offered.

Development of thermo-mechanical treatment for recycling of used concrete

Compared to virgin aggregates concrete recyclates have some specific properties because of the attached hardened cement paste. By the method of thermo-mechanical treatment, the hardened cement paste can be removed. In this paper systematic experiments are described. The aim was to understand the liberation process better. The product quality, the parameters of the process and the interaction were experimentally investigated. The results of the study show that with a low treatment temperature of 250–300 °C and a sufficient high duration of mechanical treatment recycled aggregates with properties similar to natural aggregates can be generated.

Influence of hot rolling and high speed hydrostatic extrusion on the microstructure and mechanical properties of an ODS RAF steel

An argon gas atomized, pre-alloyed Fe–14Cr–2W–0.3Ti (wt.%) reduced activation ferritic (RAF) steel powder was mechanically alloyed with 0.3wt.% Y 2O 3 nano-particles in an attritor ball mill and consolidated by hot isostatic pressing at 1150 °C under a pressure of 200 MPa for 3 h. In the aim to improve its mechanical properties the ODS steel was then submitted to a thermo-mechanical treatment (TMT): hot rolling (HR) at 850 °C or high speed hydrostatic extrusion (HSHE) at 900 °C, followed by heat treatment (HT). Transmission electron microscopy (TEM) observations of the ODS alloys after TMT and heat treatment revealed the presence of elongated grains in the longitudinal direction, with an average width of 8 μm and an average length of 75 μm, and equiaxed grains, a few microns in diameter, in the transverse direction. Two populations of oxide particles were observed by TEM: large Ti–Al–O particles, up to 250 nm in diameter, usually located at the grain boundaries and small Y–Ti–O nanoclusters, about 2.5 nm in diameter, uniformly distributed in the matrix. Charpy impact tests revealed that the HSHE material exhibits a larger upper shelf energy (5.8 J) than the HR material (2.9 J). The ductile-to-brittle transition temperature of both alloys is relatively high, in the range of 55–72 °C. Tensile mechanical properties of both ODS alloys were found satisfactory over the full range of investigated temperatures (23–750 °C). The HSHE material exhibits better tensile strength and ductility than the HR material. These results indicate that HSHE can be considered as a promising TMT method for improving the mechanical properties of ODS RAF steels.

Kinetics of Failure Rate Accumulation and TiNi Shape Memory Effect Alloy Fracture Under Mechanical Cycling

Wire specimens, d = 0.1 mm, made of Ti-(50.6-50.8)at.%-Ni alloy were exposed to thermo-mechanical treatment (TMT), thus making the samples straight and providing them with high superelasticity (ese). It was established that the most effective method of TMT is annealing with deformation at 500 and 300 °C. The optimum mode of treatment was used in the research of mechanical fatigue of alloys with high superelastic properties. Two stages characterizing the alloy behavior under mechanical cycling were found out: failure accumulation and fracture. It was shown that the duration of the cycles is determined by the value of the preset deformation (σset) in relation to the deformation on the plateau-shaped area. The results of low-cycle fatigue of the alloys under investigation were processed by means of the method of least squares. The equations of prognosis of longetivity at the preset level of deformation are presented.

Nanostructured Shape Memory Alloys for Biomedical Applications

Application of TiNi shape memory alloy in biomedical field is rapidly expanding. Some of the applications calls for non-conventional properties, which may require new methods of thermomechanical treatment and surface modification. In the present study, the effect of nanocrystallization/amorphization by various method of severe plastic deformation, such as, shot peening, cold rolling and high pressure torsion, was investigated on properties of TiNi shape memory alloys. Shot peening using iron based metallic glass media was found to be an effective method to obtain the amorphous surface. Surface amorphization improved the corrosion resistance. Nanocrystalline TiNi exhibited peculiar superelastic properties. Correlation between the microstructure and phase transformation in nanostructured TiNi was discussed.

The Corrosion Behavior of New Titanium Based Metal Ceramic Composites in Corrosive I.C. Engine Fluids

The corrosion performance of a new titanium-based metal ceramic composite (TiCAD) in HCl, HNO3, H2SO4 and in Neutral Chloride Solution, was evaluated to determine its suitability for internal combustion engines, pump valves and bodies. Silicon combines outstanding properties of both metallic and ceramic constituents in TiCAD composite, and allows its consideration as a perspective material for thermally stressed I.C. engine parts. New methods ofthermo-mechanical treatment need to be explored to improve the corrosion resistance of TiCAD composite to fully explore the advantages offered by its outstanding physical and mechanical properties.

Investigation of the stability of a technological system in combined processes of thermomechanical treatment

Consideration is given to combined thermomechanical methods of surface formation: rotational cutting with plasma heating and surface plastic deformation of a coating in electromagnetic welding. Unstable states of a technological system are investigated. Ways of controlling the stability and enhancing the efficiency of the combined methods of thermomechanical treatment are outlined.

Current state of the theory of age-hardening of metallic alloys

In recent years we have produced new types of age-hardening alloys and new hardening treatments for which the combination of several methods of hardening is typical. We should note first of all the high-nickel and chromium-nickel maraging steels and various methods of thermo-mechanical treatment for age-hardening alloys. In all cases the decomposition processes involve a high density of structural defects. Explanation of the decomposition mechanism in connection with specific types of defects is an urgent problem, the solution of which is already possible with present techniques of electron microscopy (crystallographic analysis of structural defects and new formations is possible with the use of goniometric devices in transmission electron microscopy). Further development of mathematical methods is needed for investigating phase transformations in alloys and refining the quantitative theory of the processes of precipitation and coalescence used for present-day multicomponent alloys and combined treatment. The major problem in this area of metal science is to obtain more complete characteristics of the structure of the material in the state of maximum hardness and establish quantitative relationships between the structural and strength characteristics.

Comparative effectiveness of certain methods of thermomechanical hardening of steels

1. The combination of high-temperature and lowtemperature hardening processes (CTMT) ensures a better with LTTMT. 2. The use of CTMT allows one to accomplish the same work hardening as LTTMT in the range from 20 to 25% and leads to considerable reduction of the power consumed in the deformation process by comparison with LTTMT. 3. The effectiveness of the different methods of thermomechanical treatment is connected with the nature of the alloys steels, first of all with the concentrations of carbon, chromium, and silicon. 4. We established a linear relationship between the hardness and the strength for the steels investigated, which had a martensitic structure after the various types of hardening. 5. For practical purposes it is possible to consider that the increase of the yield point with increasing hardness of the steel does not depend on the type of thermomechanical treatment.

Combined thermomechanical and magnetic treatment of metals and alloys

1. A method of thermomechanical treatment according to which the initial (untransformed) structure is work-hardened, followed by an immediate quenching so that a fine martensite structure is obtained after the structural change, results in an increased strength and ductility due to formation of an oriented arrangement of structural components and an increased number of mobile dislocations. 2. The use of a thermogagnetic treatment in which an external magnetic field is applied when a paramagnetic phase (austenite) transforms into a ferromagnetic one (martensite), is advantageous. The mechanical properties of the steel increase due to an orderly orientation of crystals refined by directed phase hardening and magnetostriction during saturation magnetizing. It is desirable to employ an electro-thermo-magnetic treatment using direct or induction heating in which the parts are cooled while under current, i.e. under a magnetic field. 3. A thermomechanical-magnetic treatment is advocated which provides work-hardening of the initial (untransformed) structure followed by a transformation of the crystals refined by working into martensite with a simultaneous superposition of the magnetic field which causes a new regular orientation and an additional structure refinement. 4. The suggested treatment, especially hardening in a magnetic field, makes the steel practically immune to temper embrittlement.