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Despite their complex composition, high-entropy alloys (HEAs) have a simple structure and have been extensively researched for their ability to achieve unique properties through thermo-mechanical processing (TMP). This review studies the effects of different rolling regimes and post-annealing on single and multiphase HEAs, analyzing how TMP leads to microstructural changes and improved mechanical properties. The rolling changes the shape and utilizes different mechanisms determined by the rolling temperature to strengthen the raw materials, thus affecting the HEAs' properties. The microstructural evolution of HEAs during annealing is affected by various parameters such as annealing time, annealing temperature, and heating rate, which impact the strength–ductility combination of HEAs. According to the literature, cryogenic rolling (cryo-rolling), as opposed to cold rolling, provides greater strengthening. This is due to the faster microstructural evolution kinetics in cryo-rolling. Thus, cryo-rolling enhances the strengthening by activating deformation twinning at earlier stages through the intersection of twins and more shear banding, which is preferred to microbands for HEAs with low stacking fault energy (SFE). Rolling at high temperatures is the most suitable approach for HEAs with low workability. Warm and hot rolling enable microstructure evolution through deformation mechanisms, including grain growth, recovery, recrystallization, and phase transformation based on the process temperature. The ratio of recovery to recrystallization depends on temperature and SFE, with recovery dominating in alloys with high SFE and at lower rolling temperatures, while recrystallization is more prevalent for alloys with low SFE and at higher temperatures, leading to specific ductility–strength synergy. [ABSTRACT FROM AUTHOR]

In this study, the effects of chemical composition and process routes on the microstructure and mechanical properties of high-Zn-content Al-Zn-Mg-Sc alloys were investigated. Aging led to the formation of nano-sized Zn phases in the grain interior and large Zn phases at the grain boundary (GB) or Al/Al3Sc interfaces in the Al-20Zn-0.5Mg-0.5Sc (20Zn-0.5Mg) alloy, and cold rolling before aging (Pre-CR) could accelerate this precipitation. Compared with the 20Zn-0.5Mg alloy, the Al-15Zn-1Mg-0.5Sc (15Zn-1Mg) alloy exhibited a more difficult Zn phase precipitation during aging, and only pre-CR could lead to the formation of intracrystalline Zn phases in this alloy during artificial aging. The transition of the η′ phases into η phases without coarsening of Zn phases occurred at the GB or Al/Al3Sc interfaces of the 15Zn-1Mg alloy during artificial aging. Pre-CR could improve the mechanical properties of high-Zn-content Al-Zn-Mg-Sc alloys, and the significant evolution of Zn phases in the 20Zn-0.5Mg alloy during processing in different routes conferred this alloy a wider range of mechanical properties than the 15Zn-1Mg alloy. [ABSTRACT FROM AUTHOR]

This article investigated the formability of aluminum/copper bimetal sheets during single-point incremental forming. First, the two-layer sheets were produced by the explosive welding process; then, the rolling process was performed with 50% strain on two-layer samples. Considering the importance of examining the mechanical and metallurgical properties on the formability of the two-layer samples, the mechanical properties were first examined, including the uniaxial tensile and micro-hardness tests. Then, metallurgical tests were performed, including scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (SEM-EDX) to investigate the fracture surface and penetration depth and an X-ray diffraction (XRD) test to check the secondary phase particles in the penetration zone of Al and Cu in five different annealing temperature conditions. Considering that the forming limit diagram (FLD) is dependent on the strain path, to study the effect of the strain path, the two-layer samples were formed by three geometries: pyramid, cone, and straight groove. Simulations of FLD by Abaqus software 6.14-4 with four different methods were studied: FLDCRT, effective strain rate (ESR), second derivation of thinning (SDT), and maximum strain rate (MSR). The results showed that the FLDCRT criterion provided a more accurate estimate of the necking time. In the following, the values of the thickness distribution were carried out by experimental and numerical methods, and the results between the methods were in good agreement. [ABSTRACT FROM AUTHOR]

Sunflower (Helianthus annuus L.), a vital crop for global vegetable oil production, encounters sustainability challenges in its cultivation. This study assesses the effects of incorporating a winter cover crop (CC), Avena sativa (L.), on the subsequent growth of sunflower crops and the vitality of their rhizosphere microbial communities over a two-year period. It examines the impact of two methods for suppressing winter CC—chemical suppression using glyphosate and mechanical suppression via rolling—both with and without the addition of phosphorus (P) starter fertilizer. These approaches are evaluated in comparison to the regional best management practices for sunflower cultivation, which involve a preparatory chemical fallow period and the subsequent application of starter P fertilizer. The methodology utilized Illumina sequencing for the analysis of rhizosphere bacterial 16S rRNA genes and fungal internal transcribed spacer (ITS) amplicons. Findings indicate a significant improvement (9–37%) in sunflower growth parameters (plant height, stem diameter, head diameter, and head dry weight) when cultivated after glyphosate-suppressed winter CC compared to the chemical fallows. Conversely, rolling of winter CC generally negatively affected sunflower growth. Rhizosphere bacterial communities following chemical suppression of winter CC showed greater Pielou’s evenness, indicating a uniform distribution of species. In general, this treatment had more detrimental effects on beneficial sunflower rhizosphere bacteria such as Hymenobacter and Pseudarthrobacter than rolling of the winter CC, suggesting that the overall effect on sunflower growth may be mitigated by the redundancy within the bacterial community. As for fungal diversity, measured by the Chao-1 index, it increased in sunflowers planted after winter CC and receiving P fertilization, underscoring nutrient management’s role in microbial community structure. Significant positive correlations between fungal diversity and sunflower growth parameters at the reproductive stage were observed (r = 0.41–0.72; p

After closure, voids need to be healed through bonding and interface dissolution to restore the mechanical properties and produce a sound product. For the prediction of void healing and the respective process optimization, a void healing criterion, spanning all three phases is needed. While hot rolling is generally suited for void healing, with large deformations at hydrostatic pressure as well as high temperatures, not all regions in the workpiece offer the same void healing conditions. Due to gradients of these metrics e. g. along the normal direction, a space-resolved approach is needed. Previously, a practical void healing criterion combining void closure and subsequent recrystallization has been proposed and applied to exemplary hot rolling processes. Besides a broader application of the criterion, adding the process parameters roll diameter and temperature, the present paper mainly aims for the experimental validation of this criterion. In bonding trials, a positive influence of temperature and strain on the bond strength has been found. While no clear correlation of the holding time on the bond strength was detectible without concurrent contact pressure the experiments suggested a saturation strain as an indicator for void healing instead. Accordingly, the criterion has been revised and a strain-based criterion proposed, applied, and compared to the previously introduced recrystallization-based void healing criterion.

In this research, corrosion behavior and discharge capabilities of the AZ61-In alloy experiencing hot rolling process have been discussed in detail. The results reveal that the introduction of indium to magnesium facilitates the dissolution of magnesium by augmenting a quantity of secondary phases, generating less-protective products. The corrosion resistance of AZI plus 50 % rolling reduction is improved attributed to the preferred basal orientation and further recrystallization. Moreover, the average discharge potentials of AZI-50 % can respectively reach −1.551 V and −1.234 V at 10 mA cm−2 and 50 mA cm−2, showing potential for application in seawater activated batteries.

The aging precipitated phases are of great significance for the strengthening and toughening of Al–Zn–Mg alloys. In this work, pre-precipitating was realized through equal channel angular pressing (ECAP) immediately followed by solid solution treatment at 475 °C for 6 h. Its corresponding strengthening and toughening effect on the room temperature (RT)-rolled Al–6Zn–1Mg alloy was systematically studied. The results indicate that pre-precipitating by ECAP can effectively improve the strength of the RT-rolled Al–6Zn–1Mg alloy and circumvent the strength-ductility trade-off. Microstructure characterization reveals that ECAP induces a large number of microshear bands, which can not only encourage recrystallization but also effectively promote the precipitation of the η′ phase. The synergistic effect of precipitation strengthening and dislocation strengthening contributes to the high strength of Al–6Zn–1Mg alloy, with UTS and YS increasing to ∼522 MPa and ∼400 MPa, respectively. Meanwhile, the ductility remains almost unchanged mainly due to the coordinated grain boundary sliding and the uniform and finely dispersed second phase particles. As a result, the strength-ductility trade-off is effectively avoided. The findings shed some light on optimizing the traditional aging treatment.

This paper presents research on the changes in the mechanical and structural properties of the commercial aluminum alloy EN-AW 7075 during thermomechanical processing. The processing involved artificial aging of the alloy at a temperature of 150°C for 30 minutes, followed by cold rolling after aging. Changes in hardness and impact toughness during the experiment were monitored. Hardness was measured using the Leeb method, while impact toughness was measured using the Charpy method. In the annealed state, the lowest hardness values were recorded, while the highest-impact toughness value was achieved in the as-quenched state. By applying cold plastic deformation after artificial aging, the hardness of the alloy significantly increased, while the impact toughness continuously decreased. After deformation of 20%, cracks appearance prevented further deformation. Optical microscopy was used to follow microstructural changes during the applied processing regime. Precipitates of various sizes and morphologies were observed in the structure. The annealed state results in poorly defined grain boundaries and formation of large precipitates relatively evenly distributed throughout the matrix. Cold plastic deformation after aging has resulted in elongated grain structure aligned with the rolling direction, along with crushing of secondary phase particles.

In this work, finite element simulation of the rolling-pressing process with horizontal and vertical rolls was carried out. To analyze the efficiency of metal processing, the main parameters of the stress-strain state were considered: equivalent strain, equivalent stress, average hydrostatic pressure, deformation force. Aluminum alloy Al6063 was chosen as the workpiece material. For variational simulation, models with a change in the heating temperature of the workpiece and the rolls rotation speed were constructed. The most optimal option is a model in which the workpiece was heated to 100 °C and deformation was carried out at a circumferential speed of the first pair of rolls of 60 rpm. Variants with a single temperature reduction to 20 °C, or rotation speed reduction to 35 rpm also give acceptable results to all the indicators considered. However, rotation speed reduction to 10 rpm makes it impossible to carry out a stable process at any temperature.

The TiB2p/Cu composites were prepared by current-assisted vacuum hot pressing (CAVHP) combined with rolling using in-situ spherical TiB2p/Cu composite powder as raw material. The effects of rolling deformation on the microstructure and properties of the sintered TiB2p/Cu composite were investigated. The results show that CAVHP leads to a rapid densification of the composite powder compact, and the subsequent rolling deformation is able to eliminate the unclosed pores and achieve a uniform distribution of TiB2p. The dynamic recrystallization during cold rolling refines the Cu matrix grains to ultrafine grains with an average grain size of 0.47 μm. The cold rolled TiB2p/Cu composite obtains a remarkable comprehensive performance with ultimate tensile strength, yield strength and electrical conductivity of 621 MPa, 567 MPa and 86.3% IACS, respectively. In addition, the strengthening and fracture mechanism of the cold rolled TiB2p/Cu composite are analyzed. This work will explore a new technological solution for the preparation of high-performance Cu matrix composites.

To explore high temperature ductility, a new Mg-2.70Zn-1.34Y-0.37Ca-0.02Zr (wt.%) alloy has been fabricated by novel multidirectional forging (MDF) and hot rolling. The microstructure and mechanical properties were investigated. The average grain size of MDF + hot rolled alloy is 10.89 ± 0.90 μm refined from the as-cast average grain size of 60.03 ± 0.72 μm. The ultimate tensile strength of 260.51 ± 1.03 MPa, yield strength of 192.29 ± 1.21 MPa, and elongation of 17.83 ± 0.72 % were obtained at room temperature. For high temperature tensile behavior, microstructural examination revealed that continuous dynamic recrystallization and discontinuous dynamic recrystallization are the main softening mechanism in the temperature range of 573–673 K, while dynamic grain growth with bimodal grains and twins is discovered at 723 K in this alloy. X-ray diffraction and scanning electron microscopy –energy dispersive spectroscopy examinations revealed that the constituent phases are composed of α-Mg solid solution and intermetallic compounds of Ca2Mg6Zn3, Mg3YZn6 (I-phase), and Mg3Zn3Y2 (W-phase). The microstructural evolution, such as dynamic recrystallization and dynamic grain growth at desired tensile temperatures, is related to the thermal stability of constituent phases. The elongation to failure of 215.4 % was demonstrated at 673 K and 1.67 × 10−2 s−1, exhibiting high strain rate quasi-superplasticity. A power-law constitutive equation was established. The deformation activation energy of 177.948 kJ/mol and stress exponent of 4.494 revealed that the dominant deformation mechanism of this alloy at elevated temperatures of 573–723 K is dislocation climb controlled by lattice diffusion.

Room-temperature (RT) formability is a key factor to broaden the applications of rolled Mg alloy sheets in the industry. However, rolled Mg alloy sheets generally form strong basal texture, where the (0001) poles align parallel to the normal direction (ND). This hinders the activation of (0001) [112¯0] basal slip, limiting the RT formability. Therefore, texture weakening, i.e., the inclination of the (0001) poles from the ND, plays an important role to improve the RT formability. Recrystallization is crucial to control the textural development in Mg, and currently, the texture weakening is commonly achieved using static recrystallization (SRX). However, the type of slipping and twinning, which are activated during rolling, affect the textural features after SRX. It is also demonstrated that shear bands and preferential grain growth are important factors to tailor the texture during SRX. Indeed, dynamic recrystallization (DRX) easily occurs during rolling in Mg, which also affects the final rolling texture, while the effect of DRX on the textural formation is not extensively studied for the development of RT-formable Mg alloy sheets. Therefore, the effect of these factors on the textural development in rolled Mg is reviewed in this manuscript. Additionally, the ideal microstructure and texture for RT-formable Mg alloy sheets are still controversial. The RT-formability includes stretch forming (biaxial tension), bending (plane strain tension), and deep-drawing. In particular, the stretch forming is commonly used to evaluate the RT-formability of rolled Mg. Although the stretch formability has been improved by recent studies, the further improvement is necessary owing to the relatively low formability of rolled Mg compared with that of rolled Fe and Al. Based on the relationship between the microstructure/texture and stretch formability provided in the literature, the design guidance for high stretch formability is proposed in this review.

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The 7046 aluminum alloy possesses a favorable fatigue property, corrosion resistance and weldability, but its moderate strength and plasticity limit its wider application and development. In the present study, severe plastic deformation (SPD) was applied prior to T6 treatment to significantly enhance the strength and toughness of the 7046 aluminum alloy. The results show that the alloy processed by four passes of equal channel angular pressing (ECAP) at 300 °C prior to T6 treatment exhibits an excellent mechanical performance, achieving an ultimate tensile strength (UTS) and elongation (EL) of 485 MPa and 19%, respectively, which are 18.6% and 375% higher than that of the T6 alloy. The mechanical properties of the alloy are further improved by an additional room temperature (RT) rolling process, resulting in a UTS of 508 MPa and EL of 23.4%, respectively. The increased presence of η′ and Al6Mn phases in the 300°C4P-R80%-T6 and 300°C4P-T6 alloys contributes to a strengthening and toughening enhancement in the SPD-processed T6 alloy. The findings from this work may shed new insights into enhancing the 7046 aluminum alloy.

ABSTRACTGround rolling delays spikelet initiation and thus would be expected to reduce frost injury in early-sown spring wheat. To characterize the relationship between the timing of rolling and the delay of spikelet initiation, we investigated apical development of early-sown spring wheat plants (Triticum aestivum L. cv. ‘Ayahikari’) rolled at the 1-, 2-, 3-, or 4-leaf stage in three years. All rollings delayed apical development. The delay was largest in plants treated at the 1- or 2-leaf stage: spikelet initiation by 5.0 days, the start of internode elongation by 5.5 days, and jointing by 3.5 days relative to the control. Our results and recent meteorological data suggest that in early cropping of spring wheat in the Tokai region of Japan, the earliest sowing date to avoid frost injury can be advanced by 3 days by rolling.

Abstract The process design of flat die rolling operations can be a tedious and costly process due to the challenges posed by small process windows. Within this work, an effort is made to closely investigate and understand the process limits caused by excessive slippage of the workpiece. Optical measurements are carried out to capture the characteristics of excessive slippage and the influence of the stroke rate and the tribological system on this process limit. Large differences in slippage were observed, depending on the tribological system. While systems with polymer based lubricants showed excessive slippage at low stroke rates, systems using oil or no lubricant endured higher stroke rates before process limits were reached. The optical measurements revealed three major forms of slippage: successful rolling without slippage, failure due to excessive slippage at process start, and failure due to excessive slippage at around one workpiece rotation.

The article is devoted to the study of specific kinematic pairs used in many areas of mechanical engineering: the so-called «rolling pairs» used in many mechanisms. The study is based on a detailed study of the structure of the «cylinder in cylinder» connection, and their geometric parameters are considered. The analysis is considered by the location of the axes of the cylinders between themselves: when the axes are parallel and when they intersect or intersect at an angle of 90 º. This study complements the data in the theory of description of kinematic pairs, in particular, rolling pairs, and makes it possible to synthesize their new types for their rational use in the mechanisms of many industries.

With the increasing application of Al-Li alloy in the aerospace field, the study of its anisotropy is conducive to the further development and utilization of Al-Li alloy. Scanning electron microscope, transmission electron microscope, X-ray diffractometer and electron back-scattered diffraction were used to observe the microstructure of 2050 Al-Li alloy with T3 status. The three-dimensional anisotropy of tensile mechanical properties of alloy plates was studied by tensile test. The results show that the strength of the rolling middle layer of 2050 Al-Li alloy plate with T3 status is the highest, the yield strength is 370 MPa, The tensile strength is 465 MPa, the elongation is the lowest at 9.6%. The transverse surface strength of alloy plate is the lowest, the yield strength is 325 MPa, the tensile strength is 431 MPa, and the elongation is the highest at 19.2%. The fracture morphology and grain size in different thickness of alloy plate are different. The grains in the surface region are thin and compact with small size, while the grains in the middle region are wide and flat with large size. The anisotropy of different thickness of 2050 Al-Li alloy plate is different: the anisotropy of yield strength and tensile strength in surface and middle region is strong, and the anisotropy of elongation is low, while the anisotropy of yield strength and tensile strength in central region is low, the anisotropy of elongation is strong. The anisotropy of different thickness of 2050 Al-Li alloy rolled plate is mainly formed by the grain orientation and texture. The strongest texture type of surface area and central area is {011}〈211〉 brass texture.

The origin of unique parallel alignment of (0001) poles to transverse direction (TD) was investigated using Mg-3Al-0.4Mn (mass%) alloy sheets rolled with different process conditions. When rolling was performed with intermediate reheating, the alloy showed a sluggish static recrystallization (SRX) behavior during post-annealing, facilitating the nucleation and growth of statically recrystallized grains from extension twins. This resulted in the apparent texture component with the parallel alignment of the (0001) poles to the TD, and the sheet exhibited good ductility for both the rolling direction (RD) and TD. In contrast, continuous rolling without intermediate reheating led to the formation of severely deformed regions near double twins. SRX was promoted at such regions, forming a typical basal textural feature with weak RD-split of the (0001) poles. Although extension twins were formed after the continuous rolling, SRX was facilitated at the severely deformed regions with double twins, and the formation of the unique alignment of the (0001) poles to the TD was suppressed. The RD-split texture led to the large elongation to failure along the RD, while it along the TD decreased owing to the narrow distribution of the (0001) poles toward the TD, resulting in the in-plane anisotropy in ductility.

Tungsten is a very important refractory metal in the fields of nuclear fusion demonstration reactor, spallation neutron source, and semiconductor. The expected properties of tungsten plates can be obtained by rolling and deforming. The DEFORM software was used to simulate the rolling of tungsten plates in large size in this paper, and the influence of rolling mode on damage factor (damage value) and strain was analyzed. The results show that, the serious damage area for one-way rolling is mainly distributed at the side edge of the billets, which is easy to produce cracks; the serious damage area for cross rolling is uniformly distributed around the billets. The strain curves of cross rolling in the rolling direction may reach a “maximum value” and then descend to a “minimum value”, and the difference of strain between the two maximum value is smaller in cross rolling than that in one-way rolling.

As the transportation industry evolves, so do its needs, creating opportunities for the use of non-standard materials. While electrically powered vehicles (EVs) generally operate at lower temperatures than those with internal combustion engines, operation at elevated temperature is still important for battery cases and motor housings. There, Mg alloy sheets could be used, as they have great potential for lightweighting. Mg–Al–Ca-alloys are particularly suitable, as they form temperature-stable phases, providing advantages compared to classical Mg–Al–Zn alloys.In this work, sheets made of an Mg–Al–Zn–Ca–Y alloy (AZXW3120) were manufactured via hot-rolling. The microstructure and texture in various conditions were analyzed and the mechanical properties were investigated at RT and 150 °C. The Ca additions led to a reduced texture after rolling and allowed for an increase in tensile strength of 15–20 MPa by age hardening. The age-hardenable AZXW3120 sheets showed better formability during cup-drawing (31.4 vs. 27.5 mm) and higher elevated temperature yield strength, of up to 25 MPa, compared to industrially produced AZ31 Mg sheet.

Introduction: The availability of high-quality gilthead seabream (Sparus aurata) larvae in larviculture represents a major bottleneck to the aquaculture. This challenge can be compounded by losses resulting from the emergence of a clinical disorder's symptomatology. In this study, the observed syndrome included a rotated positioning of the larval sagittal plane and in most cases leading eventually to death. Methods: Herein, we examined using amplicon sequencing of the 16S rDNA the bacterial communities associated with S. aurata larvae at different conditions (including both fish with no evidence of the syndrome and fish with syndrome) during the early developmental stages along with the contribution of rearing water, organic matter and provided feed in the microbiota during an experiment of 18 days. Results: Over the development of larvae, differences were observed in the bacterial composition between healthy and symptomatic larvae as well as between components of the system. A remarkable presence of members of the Psychrobacter genus was observed in symptomatic larvaewith a significant increase at 18dph. The healthy larvae harbor different bacterial profile with a dominance of Vibrio and Bacillus genera during 3-8dph, various members of Alphaproteobacteria during 11-14dph and Marinifilum at 18dph. The rearing water showed a different bacterial profile compared to the other components, with a slight effect of healthy larvae at 3-8dph. The bacteriome of feeds provided during the rearing of larvae was found to be diverse. Chlorella was mainly dominated by members of Firmicutes, while Rotifer and Artemia were mainly dominated bymembers of Proteobacteria including different species of Psychrobacter. At 18dph, Artemia feed seems to affect the symptomatic larvae bacteriome, where it enhanced the presence of Psychrobacter spp. Discussion: Interestingly, the comparative network analysis at 18dph indicated that the bacterial associations in symptomatic larvae were primarily driven by members of the Psychrobacter genus. While various phyla contributed to bacterial associations in healthy larvae with different frequencies including mainly members of Proteobacteria, Bacteroidota and Firmicutes phyla. Finally, the Gammaproteobacteria/Alphaproteobacteria ratio was found to be related to the health condition of larvae. This study provides valuable informationwhich can be used as indicators for monitoring the health status of S. aurata larvae. [ABSTRACT FROM AUTHOR]

This paper studies the behavior of a transverse through defect in an ingot during complex vortex flow of metal deformed by the radial shift rolling (RSR) method. The aim of the work was to investigate the applicability of the RSR method for the deformation treatment of oxide-dispersed strengthened steel (ODS-steel) ingots into a final semi- finished product. Vortex flow of metal promotes dispersion of alloying solid oxides and refinement of steel structure. However, the question of development or closure of possible casting defects of ODS-steel ingot remains open. For this purpose, an ODS-steel ingot with a through-hole modelling the defect was rolled according to the assumed process scheme. Also, to visualize the evolution of the defect in more detail during the rolling process, a simulation of the same defect development in an aluminum bar has been performed in 2 mm steps. The results of both rolls showed good correlation. Based on many cross-sections of the experimental bars, detailed 3D models of the defect evolution were built. An average reduction of 50 % in defect volume was found. Welding of the outer areas occurs immediately, but the central areas remain unclosed, stretching proportionally with the drawing of the rod during rolling. For this reason, RSR cannot be used with large cavity defects in the axial zone, but this method is guaranteed to weld surface defects even at low reductions. [ABSTRACT FROM AUTHOR]

The process design of flat die rolling operations can be a tedious and costly process due to the challenges posed by small process windows. Within this work, an effort is made to closely investigate and understand the process limits caused by excessive slippage of the workpiece. Optical measurements are carried out to capture the characteristics of excessive slippage and the influence of the stroke rate and the tribological system on this process limit. Large differences in slippage were observed, depending on the tribological system. While systems with polymer based lubricants showed excessive slippage at low stroke rates, systems using oil or no lubricant endured higher stroke rates before process limits were reached. The optical measurements revealed three major forms of slippage: successful rolling without slippage, failure due to excessive slippage at process start, and failure due to excessive slippage at around one workpiece rotation. [ABSTRACT FROM AUTHOR]

The solution of the elastic-plastic contact is of major importance in contact mechanics because contact damage and wear are responsible for the failure of many machine elements subjected to contact load. In many situations including gears and bearings, the load is transmitted through a small contact region, i.e. a concentrated contact, and the resulting high gradients of stress often exceed the plastic yield limit of the softer material. Plastic flow is initiated at a certain depth, resulting in modification of contact geometry and of the stress state that can lead to crack inception and propagation. Understanding the contact behaviour in the presence of plastic strains is fundamental for predicting the contact resistance. Considering the mathematical model complexity for the contact between bodies of arbitrary boundary, as well as the dissipative nature of plasticity, an analytical solution for the elastic plastic contact problem is hard to accomplish. Alongside finite element analysis, semi-analytical methods are the only existing simulation tools for the elastic-plastic contact problems. This paper extends a previously reported elastic-plastic contact solver developed by the same author, by considering friction. In the previous solver iteration, residual displacements were calculated only in the normal contact direction, thus assuming that the shear displacements are small enough to be neglected, in other words, the contact was assumed frictionless. By considering friction, a slip-stick contact process is introduced, adding a new iterative loop in which the contact pressure and shear stresses are iterated until convergence is reached. The new computer simulation tool is expected to give more realistic predictions for the elastic-plastic contact between materials with dissimilar elastic properties, in which case the shear tractions disturb the stress and displacements fields calculated for the frictionless contact case. The results are expected to contribute to a better understanding of the contact processes in the presence of both plastic strains and friction. [ABSTRACT FROM AUTHOR]

This study investigates the cold formability of twin-roll cast and rolled magnesium strips, specifically focusing on AZ31 and ZAX210 alloys. The aim is to assess the suitability of these alloys for various forming processes. The mechanical properties and formability characteristics of the strips were thoroughly examined to provide insights into their potential applications in transportation industries such as automotive and aerospace. The AZ31 and ZAX210 alloys were subjected to twin-roll casting and rolling processes to produce thin strips. The resulting strips were then evaluated for their cold formability. The results indicate that both alloys exhibit favourable cold formability. The ZAX210 alloy, in particular, demonstrates medium strengths with an average tensile strength of approximately 240 MPa at room temperature. The 0.2% proof stress values range between 136 MPa and 159 MPa, depending on the sampling direction. The total elongation values vary from 28% in the transverse direction to 32% at a 45° angle, indicating excellent ductility. Comparing the two alloys, the AZ31 alloy shows higher strengths due to its higher aluminium content. However, it also exhibits a more pronounced directional dependence of mechanical properties due to the formation of a strong basal texture during hot rolling. The transverse direction experiences reduced total elongation compared to the rolling direction, achieving only about 50% of the total elongation. The average Erichsen Index recorded for AZ31 and ZAX210 strips were 4.9 mm and 7.1 mm, respectively. The ZAX210 strip displays superior formability, which can be attributed to the fine-grained microstructure and the texture softening resulting from the weakening of the basal texture intensity and the splitting of the basal pole towards the rolling direction. In conclusion, the investigated twin-roll cast, rolled and annealed AZ31 and ZAX210 magnesium strips exhibit promising cold formability characteristics. The findings of this study contribute to the understanding of their mechanical behaviour and can guide the selection and optimisation of these alloys for various forming applications. [ABSTRACT FROM AUTHOR]

The typical and most widespread stress concentrators in the lower wing panels of aircraft are the drain holes located on the stringer vertical ribs. These are prime sources for the initiation and development of fatigue cracks, which lead to early failure of the wing structure. Therefore, improving fatigue life in these critical areas is one of the significant issues for research. Two combined methods of surface plastic treatment in the location around drain holes are discussed in this paper. Using the finite element method and ANSYS software, we created a finite element model and obtained nonlinear solution results in the case of tension in a plate with three holes. In addition, the development of residual stress due to the surface plastic treatment of the hole-adjacent areas was taken into account. In this paper, it is shown that after surface treatment of the corresponding areas of the holes, residual stress, which exceeds the yield stress for the plate material, is induced. When combined with alternative tensile stress, these reduce the amplitude of the local stresses, thus increasing the number of stress cycles before failure. The benefits of this technology were confirmed by fatigue test results, which include the fatigue failure types of the plates. Graphs showing the impact of applicable surface treatment combined methods on the number of cycles to failure were also plotted. [ABSTRACT FROM AUTHOR]

For advanced integrated circuits semiconductor chip, the uniformity of microstructure and texture is increasingly required for copper target material of ultra-high purity (≥99.9999%). To this end, well-customized rolling and annealing routes for the raw material of Cu are highly needed. In the study, unidirectional rolling (UR) and cross rolling (CR) were utilized in processing the supplied Cu, both with 50, 70, and 90% thickness reduction, respectively. The rolled samples then underwent identical annealing at 300°C for 60 min. The rolled and recrystallized microstructure and texture were characterized by electron backscatter diffraction (EBSD) and X-ray diffraction (XRD). Results showed that the CR samples exhibited severer grain fragmentation, more homogeneous microstructure and weaker texture than the UR samples, especially for the samples of 90% thickness reduction. Moreover, dynamically recrystallized grains were observed in both UR and CR samples with 90% thickness reduction due to the raised temperature during severe plastic deformation. Thanks to the more uniform deformation, the annealed CR samples enjoyed finer grains of more random textures than the annealed UR ones. Therefore, cross rolling is preferable for imparting Cu sputtering targets with the required uniformity. [ABSTRACT FROM AUTHOR]

The sheet-metal-forming process is crucial in manufacturing various products, including pipes, cans, and containers. Despite its significance, controlling this complex process is challenging and may lead to defects and inefficiencies. This study introduces a novel approach to monitor the sheet-metal-forming process, specifically focusing on the rolling of cans in the oil-and-gas sector. The methodology employed in this work involves the application of temporal-signal-processing and artificial-intelligence (AI) techniques for monitoring and optimizing the manufacturing process. Temporal-signal-processing techniques, such as Markov transition fields (MTFs), are utilized to transform time series data into images, enabling the identification of patterns and anomalies. synamic time warping (DTW) aligns time series data, accommodating variations in speed or timing across different rolling processes. K-medoids clustering identifies representative points, characterizing distinct phases of the rolling process. The results not only demonstrate the effectiveness of this framework in monitoring the rolling process but also lay the foundation for the practical application of these methodologies. This allows operators to work with a simpler characterization source, facilitating a more straightforward interpretation of the manufacturing process. [ABSTRACT FROM AUTHOR]

Multiwalled Boron Nitride Nanotubes (BNNTs) reinforced Metal Matrix Nanocomposites (MMNCs) are discussed in this work. It is noticed that the reaction of BNNTs with Aluminum (Al) to form a compound at the interface depends on the processing condition. The processing methods include sintering, solidification, rolling, High-Pressure Torsion (HPT) and heat treatment have influenced the microstructure and mechanical properties of BNNTs filled MMNCs. The review suggests that BNNTs filled MMNCs have the potential to be used in various applications. [ABSTRACT FROM AUTHOR]

In this article, effects of annealing treatment on the evolution of microstructure, tensile properties and electrical resistivity of copper-graphene nanocomposites are investigated. In order to fabricate the nanocomposite, graphene nanopowder was ball-milled after being mixed with copper powder to form a mixture of copper-graphene powder (CuG). Hot rolled copper sheets were used as the matrix of the composite which were annealed prior to accumulative roll bonding (ARB). The nanocomposite was fabricated using 2, 4 and 6 cycles of ARB leading to 20, 40 and 160 multi-layered nanocomposites. Despite increased mechanical strength, the elongation to failure and the electrical conductivity were significantly reduced which were attributed to the high defect density after severe cold deformation and strength-ductility trade-off. The effect of cold deformation on increasing electrical resistivity was so significant that no positive effects of addition of 1% CuG on reducing resistivity was observed but a slight improvement was found in the sample with 2% CuG. However, after annealing at 500 C for 2 h, ductility was fully recovered to the initial value and the electrical resistivity was significantly reduced in the nanocomposite. This was attributed to the fact that a fully recrystallized grain structure was achieved after annealing. Percentage of reinforcing agent and the thickness of the stacking layers were found to determine the final grain size. Electrical conductivity of the nanocomposite was found to significantly improve with annealing. Indeed, the electrical conductivity of the annealed 6ARB-2%CuG composite was higher than the initially annealed copper sheet while the strength and ductility were increased, as well. This determines that the combination of ARB and annealing can be used as an effective method for fabrication of copper-graphene nanocomposites. [ABSTRACT FROM AUTHOR]

In No. 3 hot strip mill at JFE Steel East JapanWorks (Chiba), mild steels are produced by the endless rolling process, in which rough rolled bars are joined and rolled continuously in the finishing mill. However, this process is not applied to high tensile strength steels because the alloy elements contained in those steels, such as silicon and manganese, form an oxide layer at the joining interface, disrupting the joining process. In laboratory joining tests, heating the joining surface until it melted resulted in discharge of the oxide layer from the interface, and steels that form oxide with a low melting temperature were successfully joined. A FEM flow analysis revealed that the viscosity of the oxide is the most important parameter for discharge. The low melting temperature of the oxide leads to low viscosity, resulting in the discharge of the oxide layer. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

During past decades, water-based and oil-in-water (O/W) based nanolubricants with nanoparticles (NPs) as additives have been developed to replace conventional oil-based lubricants for solving contamination problems during rolling processes. The formulations of nanolubricants for rolling need to be continuously improved to provide better lubrication performance. This article reviews the formulation, physicochemical properties, and lubrication mechanisms during rolling with water-based and O/W based nanolubricants, and the effects of nanolubricants on rolling force, surface roughness and oxide skin formation during rolling are discussed. This review aims to facilitate the fundamental understanding of nanolubrication and the development of rolling lubrication technology. [ABSTRACT FROM AUTHOR]

This study aims to analyze the influence of the rolling process on the microstructure and corrosion properties of the Mg/Al bimetallic bars obtained by the explosive welding method. The bars investigated were rolled using two different types of rolling: classical rolling (Variant I) and modified rolling (Variant II). Two different temperatures (300 °C and 400 °C) for each of the variables were applied as well. In this study, rods with an aluminum plating layer constituting 16.8% of the cross-sectional area and an average thickness of about 0.93 mm were investigated. Based on the revealed results, it was found that after the rolling process, the material shows clearly lower values of both icor and current in the passive range. In the joint zone of Mg/Al rods rolled at 400 °C, Al3Mg2 and Mg17Al12 intermetallic phases are distinguished, localized next to the Mg core, and characterized by columnar, coarser grains. In the transition zone closer to the Al layer, only the Al3Mg2 phase is revealed, characterized by a refined, small grain size. [ABSTRACT FROM AUTHOR]

In this study, Al-B4C/Al laminated composites with high interlayer bonding strength were fabricated by integrated hot-pressed sintering accompanied with hot rolling. The mechanical properties and interface behavior of the Al-B4C/Al laminated composites were investigated under quasi-static and impact loading. The results show that the Al-B4C/Al laminated composites obtain a high interface bonding strength, because no interlayer delamination occurs even after fractures under quasi-static and impact loads. The Al-B4C/Al laminated composites exhibit a better comprehensive mechanical performance, and the fracture can be delayed due to the high bonding strength interface. Moreover, laminated composites can absorb more impact energy than the monolithic material under impact loading due to the stress transition and relaxation. [ABSTRACT FROM AUTHOR]

The temperature gradient rolling (GTR) method effectively addresses the issue of uneven deformation of surface and core in the rolling of extra-thick plate. Different from the traditional near uniform temperature rolling (UTR) process, GTR involves a significant temperature gradient along the thickness direction of the rolled piece. As a result, the rolling force prediction model used in uniform temperature rolling cannot be directly applied in GTR. Rolling force prediction model is crucial for process control models of plate mill and serves as the foundation for plate thickness control. However, there has been limited research on rolling force prediction methods specifically for GTR. In order to predict the change of rolling force in GTR process and enhance the control of the rolling process, the current paper proposed a simplified method based on the deformation resistance model, temperature distribution fitting, differential method, and loop iteration. The precision of the method was examined by using a finite element model and plane strain experiment, demonstrating a mean error between the method and FEM was less than 5%. [ABSTRACT FROM AUTHOR]

• Effects of SRX and DRX on textural evolution in rolled Mg were reviewed. • The method for weakening basal texture in rolled Mg was provided. • Stretch formability in rolled Mg was correlated with microstructure and texture. • The design strategy for high formability in rolled Mg was provided. • The research direction for strong and formable rolled Mg was provided. Room-temperature (RT) formability is a key factor to broaden the applications of rolled Mg alloy sheets in the industry. However, rolled Mg alloy sheets generally form strong basal texture, where the (0001) poles align parallel to the normal direction (ND). This hinders the activation of (0001) [11 2 ¯ 0] basal slip, limiting the RT formability. Therefore, texture weakening, i.e. , the inclination of the (0001) poles from the ND, plays an important role to improve the RT formability. Recrystallization is crucial to control the textural development in Mg, and currently, the texture weakening is commonly achieved using static recrystallization (SRX). However, the type of slipping and twinning, which are activated during rolling, affect the textural features after SRX. It is also demonstrated that shear bands and preferential grain growth are important factors to tailor the texture during SRX. Indeed, dynamic recrystallization (DRX) easily occurs during rolling in Mg, which also affects the final rolling texture, while the effect of DRX on the textural formation is not extensively studied for the development of RT-formable Mg alloy sheets. Therefore, the effect of these factors on the textural development in rolled Mg is reviewed in this manuscript. Additionally, the ideal microstructure and texture for RT-formable Mg alloy sheets are still controversial. The RT-formability includes stretch forming (biaxial tension), bending (plane strain tension), and deep-drawing. In particular, the stretch forming is commonly used to evaluate the RT-formability of rolled Mg. Although the stretch formability has been improved by recent studies, the further improvement is necessary owing to the relatively low formability of rolled Mg compared with that of rolled Fe and Al. Based on the relationship between the microstructure/texture and stretch formability provided in the literature, the design guidance for high stretch formability is proposed in this review. [ABSTRACT FROM AUTHOR]

Effects of annealing treatment on microstructure, mechanical and damping properties of as-rolled ZK60 magnesium alloy sheets were examined and analyzed. The as-rolled alloy annealed at 340 °C for 1 h undergoes static recrystallization and exhibits the best combination of mechanical properties, with UTS of 333 MPa, YS of 268 MPa and El of 19%. With the strain amplitude below 4 × 10–4, the damping mechanism of the as-studied alloys can be explained by the Granato–Lüker (G–L) theory. With the strain amplitude higher than 4 × 10–4, the occurrence of micro-yield phenomenon and dislocation multiplication make the damping behavior of the alloy no longer explainable by G–L theory. The growth in damping becomes faster for all the alloys when the strain amplitude exceeds 4 × 10–4, and the alloy annealed at 340 °C for 1 h exhibits the highest damping capacity with the strain amplitude higher than 5 × 10–4 as a result of the activation of more non-basal slip systems, which will consume more elastic vibration energy and thus improve the damping capacity of the alloy. This provides a theoretical basis for the development of high-strength and high-damping magnesium alloys. [ABSTRACT FROM AUTHOR]

The joint influence of degree and strain rate for copper and low-carbon steel is considered. A formula for calculating the average strain resistance during rolling with the joint effect of strain rate and cold-hardening is proposed. It is shown that calculating the average deformation resistance in the compression zone with joint consideration of work hardening and strain rate is more accurate. [ABSTRACT FROM AUTHOR]

Copyright of Precious Metals / Guijinshu is the property of Precious Metals Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The mechanical properties of wrought magnesium alloys depend on their microstructure, particularly the grain size and its distribution. Conventional modeling methods struggle to accurately predict the complex physical relationship between them. In the present study, a microstructure-property mapping model based on artificial neural network was proposed to accurately predict the micro-Vickers hardness, 0.2% proof stress and tensile strength of rolled as-casting AZ31 alloy. This method considered the average grain size and its dispersion as the main influencing factors. Firstly, the diversified data of microstructure and mechanical properties of cast-rolling AZ31 alloy was obtained through multi-process and different cross rolling experiments at different initial rolling temperatures. Considering the promoting effect of nonlinear inertia weight and genetic operators on the convergence and search ability, the particle swarm optimization (PSO) algorithm was improved and subsequently introduced into the back propagation (BP) neural network to pre-training the initial weights and biases. Finally, a microstructure-mechanical property mapping model based on the improved PSO-BP neural network was constructed and verified in detail. Results show that the combination of nonlinear inertia weight and selection and crossover process of genetic algorithm can significantly improve the population diversity and convergence performance of PSO algorithm. This can optimize the initial weights and biases required for the operation of BP neural network model. The optimization ability of the model is remarkably improved in the process of establishing the microstructure-property mapping relationship.

A super-high strength Mg–9Li–1Al (LA91) alloy with ultimate tensile strength (UTS) of 312 MPa and specific strength of ∼215 kNmkg−1 was successfully achieved via a combined processing of multi-pass equal-channel angular pressing (ECAP) with repeated annealing and room temperature (RT) rolling. Significant grain refinement after ECAP led to the formation of ultrafine-grain (UFG) α-Mg phase with grain size of ∼350 nm. Further refinement of the α-Mg grains reaching ∼200 nm was achieved by further repeated annealing and RT-rolling with high dislocation density. The formation of strong basal texture of the α-Mg phase of the combined-processed alloy also contributed to the achieved excellent strength-ductility synergy. The 1 wt% Al (aluminum) in the Mg–Li dual-phase matrix acted as a high-efficient strengthening element, and was the major contributory factor to the 48% improved specific strength of the alloy compared to the UFG Mg–9Li binary alloy in our former study. The Al element distributing throughout the alloy phases without segregation contributed to the enhanced refinement of the α-Mg grains during the combined processing and improved strain-hardening rate during the tension plastic deformation, allowing for the achievement of a high strength of the LA91 alloy.

Integrating and dispersing one-dimensional (1D) nano reinforcements in metal matrix composites (MMC) is challenging due to their higher specific surface area, strong van der Waals forces within the nano reinforcement, and poor wettability with the matrix. In the present study, ultrasonic cavitation-assisted casting was employed to fabricate boron nitride nanotubes (BNNT)-reinforced aluminum matrix composites. The ultrasonic treatment (UST) demonstrated excellent deagglomeration, and dispersion of BNNTs in molten aluminum along with enhanced grain refinement potency. A remarkable ∼62% grain refinement efficiency in Al-BNNT composite compared to pure Al was achieved owing to the combined effect of UST, BNNT reinforcement and cold rolling. The increase in low-angle grain boundaries (LAGBs) by ∼58% in Al-BNNT composite, as revealed by electron backscatter diffraction (EBSD) maps, demonstrates the pileup of dislocations resulting in strength improvement. The yield strength exhibited a 97% improvement in the BNNT-reinforced composite compared to pure Al. The strengthening is attributed to UST, enhanced dislocation density and efficient bridging effect between BNNTs and the matrix. Thus, the present study constitutes the first successful report on the role of UST in the mechanism of BNNT dispersion, grain morphology and enhanced mechanical properties, including cold rolling of BNNT-reinforced MMC. Successful dispersion of BNNTs by ultrasonic cavitation confirms that UST technology is a promising method for manufacturing high-strength nanoparticle-reinforced lightweight metal matrix composites.

In order to further improve the comprehensive mechanical properties of commercial AZ31 Mg alloy, AZ31/graphene nano particulates (GNP) composites were prepared by AZ31 Mg alloy and graphene through friction stir processing (FSP) and following rolling. The microstructure and mechanical properties of as-FSPed and as-rolled alloys were investigated in this study. Compared with base metal, the ductility of FSPed alloys is greatly increased, while the strength is somewhat decreased. After further rolling on the FSPed plate, the strength of the alloy is improved. AZ31/GNP composites processed by FSP and rolling (50% reduction ratio) exhibits excellent mechanical properties with ultimate tensile strength of 296 MPa and elongation of 15.7%. The improved performance is attributed to the refinement of the grain and the homogenization of the second phase, which are the result of the severe plastic deformation characteristics of FSP. The multiplication of dislocations originated from rolling deformation and the reinforcement of GNP also contribute to the strength. The results verify that FSP as an intermediate step before rolling can be used as an effective mean to add reinforcement particles. On the other hand, the improved microstructure induced by severe plastic deformation of FSP is beneficial for further rolling.

In this study, the role of microstructure in tailoring the mechanical properties and corrosion behaviors of as-rolled dilute Mg–Bi binary alloys (MB-x, where x = 0.2 and 0.8 wt%) without/with Mg3Bi2 nanoprecipitates along the grain boundaries was systemically explored. The MB-0.8 alloy with Mg3Bi2 phases exhibited superior strength, ductility, and anticorrosion synergy (with a tensile yield stress of 235 MPa, ultimate tensile strength of 285 MPa, elongation of 10.3%, and Pi-168h of 0.105 mm/y). Strength–ductility synergy was achieved owing to the grain boundary strengthening and activation of prismatic and/or pyramidal slip systems. The transformation of the corrosion mode inhibited the corrosion of the MB-0.8 alloy. Therefore, our approach provides an effective strategy for developing Mg alloys that exhibit superior characteristics.