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The century-long problem of conversion of plastic work to heat is controversial and challenging. In this work, 2D and 3D molecular simulations of crystal Cu are carried out to study the micro-mechanism of plastic work converting to heat. The results show that heat generation comes along with lattice restoration, transferring part of potential energy of defects, i.e., stored energy of cold work (SECW), to kinetic energy. As a result, specific crystallographic defects generate amounts of heat corresponding to variations of their SECW. If the change of microstructure and temperature are only detected at the surface of the system, the time lag of heat generation will be observed. The simulation results are indispensable accompaniments of experimental research, unveiling how plastic heat is affected by the type, propagation path, and density of defects, providing nano-scale explanations for the time lag of temperature rising in experiments. [ABSTRACT FROM AUTHOR]

The Taylor–Quinney coefficient (TQC) stands as a critical parameter intricately linked to the thermomechanical coupling plastic deformation behavior, defined as the ratio of heat generation to plastic work. Combining experimental studies and atomistic simulations, the TQC is discussed in the context of three CoCrNi-based chemically complex medium/high-entropy alloys (CoCrNi, CoCrNiFe, and CoCrNiFeMn). Notably, the obtained TQC of these alloys hovers around 0.7, well below the generally assumed value of 0.9–1 in traditional metals associated with adiabatic shearing. The lower TQC implies that these alloys possess the much better capability of storing energy of cold-work. It is further found that immobile dislocations are the most effective carriers for storing the energy of cold-work. Among these three alloys, CoCrNiFeMn exhibits the highest TQC due to its relatively lower density of immobile dislocations and Lomer–Cottrell locks. [ABSTRACT FROM AUTHOR]

The initial microstructure of cold-worked Ti-added 14Cr–15Ni stainless steel was modified through short-term aging and its influence on creep properties has been investigated at a test temperature of 973 K and two stress levels of 150 and 175 MPa. The improvement in rupture life of the condition comprising of post-aging was nominal at 175 MPa, but enhanced more than two times at 150 MPa when compared to the condition which comprised of prior cold work alone. Microstructural examination after creep testing showed that though M23C6 type of precipitates was prominent in both conditions, their size distribution varied with respect to processing condition (viz., one with prior cold work and another comprising of prior cold work followed by aging) as well as applied stress. Retention of cold work-induced dislocation structures aided by secondary TiC precipitates in the aged condition enhanced the rupture life at 150 MPa. Extensive recovery of the dislocation substructure was observed in the unaged condition tested at the same stress level. The size distribution of the dimples observed from the fractographs could be correlated with the extent of creep-induced cavitation. This work describes how the two preprocessing conditions influence the nucleation of M23C6 and secondary TiC precipitates during creep deformation. [ABSTRACT FROM AUTHOR]

The AA2219 is an Al-Cu alloy with widespread engineering applications. The sheet parts of this alloy are produced by metal forming and are subjected to age hardening (e.g., T6 temper) for strengthening. The cold work in metal forming affects the ageing behavior of alloy and hence the resulting mechanical properties. In this research, a novel forming technique namely Incremental Forming with three different forming-ageing routes is employed to produce age-hardened AA2219 parts. The resulting microstructure evolution, mechanical properties, and residual stresses are examined. The results reveal that forming imposed cold work (35% plastic strain) enhances the sheet strength and hardness to a certain extent, which can be further enhanced by opting an optimum forming-ageing route. Similarly, the residual stresses also show sensitivity to the forming-ageing route opted. Based upon extensive analysis of the experimental results, it is concluded that the [O-IF-ST-T6] route is the most appropriate route for producing age-hardened parts with high strength, hardness and ductility, and low residual stresses (where O, IF, ST, and T6 represent parent, incremental forming, solution treatment and T6 ageing, respectively). This route is found to offer a gain of 238% in the tensile yield strength, 151% in the ultimate tensile strength, and 200% in the hardness with respect to the parent metal. Further, from several correlations drawn between mechanical properties and microstructural quantities, namely grain size, and precipitate's size and density, strengthening mechanism is revealed for the reported gains. [ABSTRACT FROM AUTHOR]

The present research focuses on enhancing the mechanical properties and the electrical conductivity of alloys corresponding to the Al-Mg-Zn (two different compositions) and Al-Mg-Si systems, compared with the commercial 6201-T8 and 1350-H16 alloys, by using a novel approach based on T8 tempering (solution heat treated, cold worked, then artificially aged). After T8 tempering, the Al-Mg-Zn and Al-Mg-Si alloy systems show a better combination of electrical and mechanical properties, with an enhancement of the electrical conductivity by about 2.8% compared to that of 1350 alloy and 13% higher than for the 6201 alloy series. All studied alloys exhibit better mechanical properties than 1350-H16 and are similar to those of 6201-T8. [ABSTRACT FROM AUTHOR]

Traditionally, precious metals are processed by either lost-wax casting or the casting of semi-finished products followed by cold or hot working, machining, and surface finishing. Long process chains usually conclude in a high material input factor and a significant amount of new scrap to be refined. The maturing of Additive Manufacturing (AM) technologies is advantageous with regard to resources among other criteria by opening up new processing techniques like laser-based powder bed fusion (LPBF) for the production of near net shape metal products. This paper gives an insight into major advantages of the powder-based manufacturing of precious metal components over conventional methods focusing on product carbon footprints (PCF). Material Flow Cost Accounting (MFCA) for selected applications show energy and mass flows and inefficient recoverable losses in detail. An extended MFCA approach also shows the greenhouse gas (GHG) savings from avoiding recoverable material losses and provides PCF for the products. The PCF of the precious metals used is based on a detailed Life Cycle Assessment (LCA) of the refining process of end-of-use precious metals. In the best case, the refining of platinum from end-of-life recycling, for example, causes 60 kg CO2e per kg of platinum. This study reveals recommended actions for improvements in efficiency and gives guidance for a more sustainable production of luxury or technical goods made from precious metals. This exemplary study on the basis of an industrial application shows that the use of AM leads to a carbon footprint of 2.23 kg CO2e per piece in comparison with 3.17 kg CO2e by conventional manufacturing, which means about a 30 percent reduction in GHG emissions and also in energy, respectively. [ABSTRACT FROM AUTHOR]

This paper reviews the development of ultrasonic surface treatment techniques, including ultrasonic shot peening, ultrasonic peening treatment, and ultrasonic surface rolling techniques. Ultrasonic surface treatment techniques are effective technologies to induce severe plastic deformation and improve the mechanical properties and surface integrity of components. In recent years, numerous researchers have explored various ultrasonic surface treatment techniques to improve surface integrity using available facilities and equipment. Besides, due to the limitations in industrial applications, these techniques are expanding to improve various surfaces with specific geometric shapes. Despite the wide range of techniques in this field, this review focuses solely on industrial applications based on cold working. This article briefly explains each technique and its advantages and disadvantages compared to other techniques. Applications of these techniques are presented with descriptive illustrations, and their effects on the surface characteristics of ferrous and non-ferrous materials are summarized. Based on this, the existing shortcomings and limitations are discussed in this paper, and prospects for ultrasonic surface treatment approaches in future studies are considered. The present review enhances the knowledge of ultrasonic surface treatment techniques and provides a quick reference for the appropriate usage of each technique in relevant applications. [ABSTRACT FROM AUTHOR]

Effective execution of military missions in cold environments requires highly trained, well-equipped, and operationally ready service members. Understanding the metabolic energetic demands of performing physical work in extreme cold conditions is critical for individual medical readiness of service members. In this narrative review, we describe 1) the extreme energy costs of performing militarily relevant physical work in cold environments, 2) key factors specific to cold environments that explain these additional energy costs, 3) additional environmental factors that modulate the metabolic burden, 4) medical readiness consequences associated with these circumstances, and 5) potential countermeasures to be developed to aid future military personnel. Key characteristics of the cold operational environment that cause excessive energy expenditure in military personnel include thermoregulatory mechanisms, winter apparel, inspiration of cold air, inclement weather, and activities specific to cold weather. The combination of cold temperatures with other environmental stressors, including altitude, wind, and wet environments, exacerbates the overall metabolic strain on military service members. The high energy cost of working in these environments increases the risk of undesirable consequences, including negative energy balance, dehydration, and subsequent decrements in physical and cognitive performance. Such consequences may be mitigated by the application of enhanced clothing and equipment design, wearable technologies for biomechanical assistance and localized heating, thermogenic pharmaceuticals, and cold habituation and training guidance. Altogether, the reduction in energy expenditure of modern military personnel during physical work in cold environments would promote desirable operational outcomes and optimize the health and performance of service members. [ABSTRACT FROM AUTHOR]

The examination of mechanical and wettability properties of commercial pure titanium (CP-Ti) introduced a novel challenge. The microstructure of samples was analyzed by using OM and SEM micro-images. In this study, the hardness of the surface and cross section of samples was evaluated, and the effect of several surface mechanical attrition treatments (SMATed) on samples was examined. Also, the tensile test was done to compare the effect of SMAT duration on mechanical properties of samples. The contact angle method was then employed to investigate the impact of SAMT duration on the wettability trend. According to results, as the treatment time increases, twins become evident in the deeper layers of the samples. In contrast, the near-surface twins are shorter than those found in the deeper material, signifying the presence of finer grains. Moreover, the elevated hardness in SMATed samples can be attributed to several key factors, including cold work, a rise in defects and twins, and grain refinement. The surface hardness increases across the sample series (up to Ti6) due to the substantial energy input. Nevertheless, it is anticipated that further continuation of the process will result in a constant surface hardness. The increased strength observed in SMATed samples can be attributed to factors such as reduction in grain size and the formation of twins. The wettability results show that the treated surfaces exhibited a significant change in wettability compared to the untreated samples, with a 25% reduction in the contact angle. This is attributed to the surface modifications induced by the treatment process, which introduced more hydrophilic functional groups. The results also show that after 4 h of treatment, the contact angle increases, suggesting that the trend may plateau with additional treatment time. [ABSTRACT FROM AUTHOR]

Copyright of Revista Foco (Interdisciplinary Studies Journal) is the property of Revista Foco 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.)

In the current investigation, cold work influence on mechanical strength, microstructure, hardness and ductile to brittle transition (DBT) in pure (P) 304 L-stainless steel (SS) (with ultra-low content of sulphur (0.001%) and phosphorus (nil) at several levels of cold work (5%, 10%, 20% and 30%) are reported, which provide valuable information regarding beneficial effects of reduced level of sulphur for the material selection in structural design. The cold work results in dual-phase (γ + ${\rm{\alpha {^{\prime}}}}$ α ′ ) with distinct values of dislocation densities and grain size that are used in the modified Hall-Petch equation to obtain the corresponding change in yield strength. Cold working up to 30% increased yield strength (${{\rm{\sigma }}_y}$ σ y ) from 280 to 900 MPa, whereas ultimate tensile strength (${{\rm{\sigma }}_u}$ σ u ), increased from 620 to 950 MPa, i.e. an increase of 34.73%. The hardness values increased from 172 to 360 Hv, i.e. an enhancement of 110.5% for a cold work of 30%. The material showed a remarkable enhancement in the impact energy absorption from 200 to 390 J for a temperature change from 77 to 473 K. It is observed that cold working at 5% level reduces the impact energy absorption from 390 to 250 J, i.e. reduction of 35.89% at 298 K. The value of impact energy absorbed by P-304 L-SS was 37% higher than the commercial grade 304 L-SS (sulphur (0.03%), phosphorous (0.04%). The study succinctly brings out the importance of reduced content of sulphur and phosphorus in obtaining superior mechanical properties through cold work. [ABSTRACT FROM AUTHOR]

Normally closed (NC) pyrovalves made of annealed SS304L are used in the propulsion system of liquid engines in satellite launch vehicles. NC pyrovalves prevent the fluid flow when closed and upon activation (i.e. opening) allow fluids to flow. During functional testing of valve, flow did not occur upon activation. Detailed observation revealed the activation by firing of the cartridge, but the flow path did not open due to non-separation of fluid line closed ends (i.e. diaphragm closed ends). Further analysis indicated that the diaphragm material was harder than intended, surpassing both its specified hardness and the hardness of the piston material. The diaphragm material was found to be in cold worked condition in place of annealed condition. This indicates that the material to be cut (i.e. diaphragm material with an average hardness of 304 ± 5 VHN) is harder than the cutter (i.e. piston material with an average hardness of 154 ± 12 VHN). Due to the higher strength of diaphragm material as indicated by the higher hardness than expected, the mechanical force exerted by the piston on firing of explosive cartridge could not cut/separate the diaphragm and flow path did not establish leading to the failure of pyrovalve operation. [ABSTRACT FROM AUTHOR]

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology 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.)

Springback error is a major obstacle in L-bending sheets via cold working. Although thermal processing can effectively reduce the springback phenomenon, it is challenging to heat the sheet globally due to the influence of working conditions. Therefore, this study applied local induction heating to reduce the springback of 45 steel sheets and investigated the effects of bending parameters on springback behavior. Initially, a thermodynamic coupling model and a static model were created utilizing the VOCE hardening model and the von Mises yield criterion in the ANSYS workbench 2022 R2 software. The springback behavior and stress distribution of the sheets were then investigated under different temperatures (room temperature and 800 °C) and bending angles (15°, 30°, 45°, 60°, 75°, and 90°). Simultaneously, the experiments were performed to investigate springback behavior and guarantee the accuracy of the model. The results indicate that the springback reached a minimum value at the 45° bending angle at room temperature while increasing with the increasing bending angle under 800 °C local heating. The springback under local heating can be decreased by 75.2% and the error of the bending angle can improve by 2–7° compared with samples processed in room temperature. [ABSTRACT FROM AUTHOR]

The softening and strengthening mechanism induced by cold work of Cu-Al2O3 composite with 0.1wt.% Al content was investigated in this paper. These results show the microstructure while cold work exhibits a strong <001>//X0 and <111>//X0 double fiber texture along the deformation direction (X0). However, except for grain refinement, the intensity of the <111>//X0 fiber texture gets better as the plastic deformation increased levels, accompanying the formation of high-density dislocations. As a result, the improving strengthening effects from the grain boundary, texture, and dislocation are responsible for hardening induced by the cold work. However, the dislocation strengthening effect induced by the cold work with large plastic deformation is lower than that with moderate plastic deformation, resulting from the decreasing dislocation density. Therefore, it is suggested that the work softening phenomenon by the large plastic deformation is attributed to the weakening dislocation strengthening compared to the moderate plastic deformation. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Babylon Center for Humanities Studies is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) 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.)

Most bulk metallic materials reveal an increased strength but a loss of ductility after cold deformation, a phenomenon known as the strength–ductility trade-off. In this study, we propose a strategy to overcome this problem by introducing a high density of crystalline defects into a Fe-based metastable alloy by refining grains to a nanometer scale. This procedure effectively enhances the kinetics and reduces the driving force for transformation-induced plasticity (TRIP). Consequently, the TRIP effect originally occurring at cryogenic temperature in the studied alloy becomes active at ambient conditions, contributing to a strength–ductility synergy and overcoming cold working induced sacrifice of ductility. High-density crystalline defects were introduced into a metastable alloy, leading to an increase in TRIP temperature. This helps to overcome the strength–ductility trade-off in the severely plastic-deformed alloys at ambient conditions. [ABSTRACT FROM AUTHOR]

The aluminum alloy shell fabricated by ‘bending + high-frequency welding’ is the core component of the Chinese new energy vehicle battery pack. Still, this process cannot produce the next generation of shell products with unequal wall-thickness. In this study, we take the unequal-wall-thickness square 3003 aluminum alloy battery shell with a wall thickness of less than 0.5 mm and a tolerance range of «30 µm as the research object. According to the cold work, hardening characteristics of 3xxx series aluminum alloys, hot extruded hollow blanks were prepared, and a new cold drawing process was attempted to be developed on this basis. Based on the analysis of the stress-strain field during cold drawing of defective workpieces, the size of the die inlet’s R angle and the blank’s size were optimized to solve the problems of local fracture and tearing of the blank. The results show that the maximum stress during cold drawing occurs at the fillet where the sizing zone intersects with the wall-thinning zone. This location is subjected to tensile stress, normal pressure from the inner and outer dies, and tangential friction force, causing a material accumulation phenomenon; the material flow velocity along the cold drawing direction is inconsistent, which will cause U-shaped patterns on the surface of finished products; the strain value along the cold drawing direction first increases and then decreases with the rise of R angle, reaching the maximum when the R angle size is 1.5 mm. After optimization, the maximum equivalent stress decreased from 205 MPa to 190 MPa, and the average strain along the cold drawing direction increased from 0.15-0.22 to over 0.3. This study successfully prepared precisely ultra-thin lithium iron phosphate battery shells by optimizing cold drawing process parameters and die structure. [ABSTRACT FROM AUTHOR]

One challenge in developing new materials is solid metal-induced embrittlement, where the fracture stress or ductility of the metal decreases upon contact with another metal surface. Materials such as aluminium demand precise temperature control for optimal results, often requiring specialized equipment. Strengthening aluminium alloys often involves cold working techniques like wire drawing or cold rolling. By combining methods such as cold working, heat treatment, and most especially alloying, the mechanical properties of aluminium alloys can be optimized. To address these concerns, an experimental study investigated the nanomechanical response of an alloy developed for anti-corrosion and structural applications. Corrosion behaviour was evaluated in a 3.65 wt% NaCl solution using a potentiostat/galvanostat, while tribological performance was assessed using a reciprocating sliding tribometer. Microhardness properties were studied using a Vickers microindenter, and thermal stability was examined using a thermo-gravimetric analyzer. Structural modifications were analysed using SEM/EDX and X-ray diffractometer (XRD). Results showed that the HEA (high entropy alloy) 17 sample exhibited outstanding corrosion resistance, with a corrosion rate (CR) of 0.0639 mm/year and corrosion current density (jcorr) of 5.500E−06 A/cm2. All HEA samples displayed high wear rates and worn track sections compared to CONTROL 2. The HEA 16 and HEA 18 samples demonstrated notably high Vickers hardness of 534.50 µN/mm2 and 533.48 µN/mm2, respectively. Despite its high copper content, the CONTROL 1 sample did not exhibit comparable hardness. SEM images revealed refined microstructures and distinct outer morphologies in the examined samples. [ABSTRACT FROM AUTHOR]

Lug joints are preferred joineries for transferring heavy loads to parent components in aerospace vehicles. They experience corrosion due to environmental conditions, improper surface finishes and rubbing displacement between the pin and lug-hole. This causes damage of different sizes and shapes near the lug-hole. Stiffness degradation due to corrosion-induced damage is modelled as a through-pit at one of the identified critical locations through stress analysis. The effect of this pit on fatigue crack initiation life is estimated. Lug-hole is pre-stressed by cold-working and the benefits of inducing plastic wake on the intended performance of the lug joint during the damages due to corrosion are brought out and compared with non-cold-worked lug-hole. Numerical analysis is performed on this lug joint with press-fit. The results obtained highlight the benefits of cold-working and the methodology can be extended to damage growth and analyse the effect of surface treatments for better structural integrity of components of aerospace vehicles. [ABSTRACT FROM AUTHOR]

When placed under cryogenic temperatures (below −180 °C), metallic materials undergo structural changes that can improve their service life. This process, known as cryogenic treatment (CrT), has received extensive research attention over the past five decades. CrT can be applied as either an autonomous process (for steels and non-ferrous alloys, tool materials, and finished products) or as an assisting process for conventional metalworking. Cryogenic impacts and conventional machining or static surface cold working (SCW) can also be performed simultaneously in hybrid processes. The static SCW, known as burnishing, is a widely used environmentally friendly finishing process that achieves high-quality surfaces of metal components. The present review is dedicated to the portion of the hybrid processes in which burnishing under cryogenic conditions is carried out from the viewpoint of surface engineering, namely, finishing–surface integrity (SI)–operational behavior. Analyzes and summaries of the effects of cryogenic-assisted (CrA) burnishing on SI and the operational behavior of the investigated materials are made, and perspectives for future research are proposed. [ABSTRACT FROM AUTHOR]

The article is aimed at identifying the influence of laser texturing and subsequent coating with a hard, wear-resistant coating AlCrSiN (nACRo®) on selected tribological properties of the analyzed tool steels for cold work, produced by conventional and powder metallurgy. The substrate from each steel was heat treated to achieve optimal properties regarding the chemical composition and the method of production of the material. Böhler K100 and K390 Microclean® steels were used. These are highly alloyed tool steels used for various types of tools intended for cold work. The obtained results show that the coefficient of friction is increased by coating, but the wear rate is lower compared to the samples which were only textured. [ABSTRACT FROM AUTHOR]

The aim of the article was to determine the impact of crushed condition (work hardening) on the effectiveness of the vibratory machining. The vibratory machining processing was carried out in two steps. The first step consisted of mechanical abrasion and remove oxides from the surface of the workpieces with abrasive media. While in the second step, smoothing - polishing with metal media was performed. Vibratory polishing also strengthened the treated surfaces. The test results were compared for samples in the crushed state (work hardening, plastic processing) and samples subjected to recrystallization annealing heat treatment. Mass losses, changes in the geometric structure of the surface and changes in the hardness of the machining surfaces were analyzed. Samples subjected to recrystallization, as compared to the samples in the state after work hardening-plastic working, are characterized by a slightly higher arithmetic mean surface roughness and lower surface hardness than for analogous processes for samples not subjected to heat treatment. Heat treatment of annealing allows to remove the effects of crushing and thus it is possible to obtain larger mass losses. Smaller burrs dimensions were obtained for samples after the heat treatment -- annealing than after work hardening. [ABSTRACT FROM AUTHOR]

Austenitic stainless steel has high toughness and plasticity; however, it tends to exhibit low yield strength, which severely limits the widespread application of this steel. It can be strengthened by cold working; however, this will cause many defects in the structure. Therefore, annealing treatment must be carried out before use. In this paper, the effects of annealing treatment at different temperatures and times on the microstructure and mechanical properties of cold-rolled 305 stainless steel sheet were studied and the theoretical mechanism was further analyzed to provide better theoretical guidance for production and application. It was found that the microstructure grains obtained by annealing at 850 °C for 30 s were finer and more uniform, and the mechanical properties were also the best, which met the requirements of strong plasticity. Therefore, the rolling and annealing experiments could be carried out again under this annealing condition, and the requirements of the finished product could be finally obtained. At this time, the thickness of the plate was about 0.15 mm, the yield strength was 1238 MPa, and the permeability was below 1.02, which met the production requirements of the metal mask plate. [ABSTRACT FROM AUTHOR]

This article explores the other side of hegemony – a concept central to John Krige's work on co-production and transnational history. Focusing on the case of Gerald Bull, university professor-turned-weapons dealer, it examines how individuals working on the edges of Cold War empires cobbled together practices, objects, and geographies that evaded and exploited the power of nation-states. Tracing those concerns from North America to Barbados and Iraq, the article suggests how we might avoid reproducing (or producing anew) the hegemonies we study. [ABSTRACT FROM AUTHOR]

In this paper, a new high-temperature methodology for determining the 'effective' corrosion rates of internal pressure-tested cladding tubes, based on the reduced creep failure times under exposure, is presented. The methodology has been developed to estimate the combined damage accumulation of corrosion and creep and to establish temperature limits for the use of 1515Ti claddings in high-temperature Lead-Bismuth-Eutectic (LBE). The results are compared to static corrosion rates determined from earlier test campaigns in stagnant LBE. All tests are conducted on 24% cold worked 1515Ti cladding tubes that are the SCK CEN reference material for the MYRRHA design efforts. The virgin material creep model that is the basis for the corrosion rate estimation, has been fitted on an extended creep failure database and a life-fraction rule is applied to accommodate for the life reduction caused by the sought 'constant' effective corrosion rate. [ABSTRACT FROM AUTHOR]

This study presents the results of research, the aim of which was to analyze the uniformity of the distribution of selected mechanical properties along the length of a 5.5 mm diameter wire rod of 20MnB4 steel for specific thermoplastic processing parameters. The scope of the study included, inter alia, metallographic analyses, microhardness tests, thermovision investigations, and tests of the wire rod mechanical properties (yield strength, ultimate tensile strength, elongation, relative reduction in area at fracture), along with their statistical analysis, for three technological variants of the rolling process differing by rolling temperature in the final stage of the rolling process (Reducing Sizing Mill rolling block [RSM]) and by cooling rate using STELMOR® cooling process. The obtained results led to the conclusion that the analyzed rolling process is characterized by a certain disparity of the analyzed mechanical properties along the length of the wire rod, which, however, retains a certain stability. This disparateness is caused by a number of factors. One of them, which ultimately determines the properties of the finished wire rod, is the process of controlled cooling in the STELMOR® line. Despite technological advances concerning technical solutions (among them, increasing the roller track speed in particular sections), it is currently not possible to completely eliminate the temperature difference along the length of the wire rod caused by the contact of individual coils with each other. From this point of view, for the analyzed thermoplastic processing parameters, there is no significant impact by the production process parameters on the quality of the finished steel product. Whereas, while comparing the mechanical properties and microstructure of the wire rod produced in the different technological combinations, it was found that the wire rod rolled in an RSM block at 850 °C and cooled after the rolling process on a roller conveyor at 10 °C/s had the best set of mechanical properties and the smallest microstructure variations. The wire rod produced in this way had the required level of plasticity reserve, which enables further deformation of the given type of steel in compression tests with a relative plastic strain of 75%. The uniformity of mechanical properties along the length of wire rods designed for further cold plastic working processes is an important problem. This is an important issue, given that wire rods made from 20MnB4 steel are an input material for further cold plastic working processes, e.g., for the drawing processes or the production of nails. [ABSTRACT FROM AUTHOR]

The effect of cold working on hydrogen embrittlement of Monel-400 alloy has been investigated in this report. Monel-400 alloy having 50 and 60% cold working has been selected for this study. A part of these cold-worked materials is annealed. A series of slow strain rate tensile tests of the cold-worked as well as annealed materials are carried out in two different environmental conditions—air and with hydrogen charging in 3.5% NaCl solution. Alloy with 60% cold working exhibits the highest reduction in ductility with hydrogen charging. The reduction in ductility is lower for the annealed materials compared to that of cold-worked materials when tested with hydrogen charging. The results lead to infer that (i) the alloy becomes more detrimental to hydrogen embrittlement with the increase in percentage cold working, which reduces ductility significantly with increasing strength under hydrogen charging, (ii) annealing of cold-worked materials decreases their susceptibility to hydrogen embrittlement, and (iii) hydrogen damage promotes brittle fracture for the cold-worked materials. [ABSTRACT FROM AUTHOR]

Chromium–nickel austenitic stainless steels are widely used due to their high corrosion resistance, good weldability and deformability. To some extent, their application is limited by their mechanical characteristics. As a result of their austenitic structure, increasing the static and dynamic strength of the components can be achieved by surface cold work. Due to the tendency of these steels to undergo intercrystalline corrosion, another approach to improving their mechanical characteristics is the use of low-temperature thermo-chemical diffusion processes. This article proposes a new combined process based on sequentially applied diamond burnishing (DB) and low-temperature gas nitriding (LTGN) to optimally improve the fatigue strength of 304 steel. The essence of the proposed approach is to combine the advantages of the two processes (DB and LTGN) to create a zone of residual compressive stresses in the surface and subsurface layers—the enormous surface residual stresses (axial and hoop) introduced by LTGN, with the significant depth of the compressive zone characteristic of static surface cold working processes. DB (both smoothing and single-pass hardening), in combination with LTGN, achieves a fatigue limit of 600 MPa, an improvement of 36.4% compared to untreated specimens. Individually, smoothing DB, single-pass DB and LTGN achieve 540 MPa, 580 MPa and 580 MPa, respectively. It was found that as the degree of plastic deformation of the surface layer introduced by DB increases, the content of the S-phase in the nitrogen-rich layer formed by LTGN decreases, with a resultant increased content of the ε-phase and a new (also hard) phase: stabilized nitrogen-bearing martensite. [ABSTRACT FROM AUTHOR]

Current methods for modeling hybrid additive manufacturing are computationally inefficient for use in optimization algorithms. An analytical tool is needed to understand how cycling thermal and mechanical loads via 3D printing and cold working reshapes cumulative residual stress within a build volume. A novel analytical model was developed that couples beam theory and superposition to rapidly predict cumulative residual stress. Modeling results were experimentally validated on AlSi10Mg after laser shock peening prescribed layers during powder bed fusion. Results demonstrated a vertically translating heat-affected zone, and the use of beam-based superposition accurately accounted for residual stress redistribution from cyclic printing and peening. [ABSTRACT FROM AUTHOR]

The article presents a new method called slide roller burnishing (SRB) for the cold working of cylindrical surfaces on machine tools implemented with a novel multi-functional device. The machined material is chromium–nickel austenitic stainless steel. The deforming element is a toroidal roller whose axis crosses that of the workpiece. As a result, a relative sliding velocity occurs in the contact zone between the roller and the machined surface. The sliding velocity vector is set using the burnishing device. The theoretical background of SRB is presented. When the two axes are parallel, the well-known roller burnishing (RB) method is implemented. Thus, RB is a special case of SRB. Both processes are realized using the multi-functional burnishing device. The RB process was studied experimentally and optimized according to three criteria, based on the relationship between the surface integrity and operating behavior of the respective component, to achieve three processes: smoothing, hardening, and mixed burnishing. Using the optimal RB parameters obtained, the dependence of the results of SRB on the crossing angle was investigated and optimized. A comparative analysis was performed between the optimized RB and SRB processes (respectively for their three variants: smoothing, hardening, and mixed) based on geometrical and physical–mechanical characteristics of the surface integrity. The main advantage of the SRB is that it provides smaller height roughness parameters (improvement by 42%) and a higher surface microhardness (improvement by 7%) than RB. [ABSTRACT FROM AUTHOR]

The influence of texture on strength was investigated by altering the amount of cobalt in Ni-Co alloys. The purpose of incorporating Co was to reduce the stacking fault energy (SFE) of the alloy. A decrease in the SFE reduces the ease of cross-slip and enhances planar slip, leading to changes in texture during cold working. Three Ni-Co alloys (33, 50, and 60 wt pctCo) were wire drawn at room temperature in a specially designed setup to wire diameters of 500, 200, and 100 μm, corresponding to a drawing strain of 2.67, 4.05, and 5.88. EBSD analysis revealed a refinement in grain size with drawing strain as well as a transition from elongated to equiaxed grains in Ni-50 and Ni-60 Co alloys. Line profile analysis and bulk texture analysis showed that increasing drawing strain leads to a higher defect density, an increased <100> fiber fraction and a decreased <111> fiber fraction, with the trends increasing with an increase in Co content. Tensile tests on the drawn wires show that Ni-60 Co alloy has higher strength with superior ductility for all wire diameters. The HP coefficients for the annealed conditions, calculated by annealing Ni-Co wires of 100 μm diameter, was found to be independent of SFE. The HP coefficients in drawn conditions were found to be higher than in the annealed conditions. The activation volume measured from the multiple stress relaxations in the drawn wires ranged from 20 to 5.5 b3, suggesting that dislocation interactions remained the underlying operating deformation mechanism. [ABSTRACT FROM AUTHOR]

This work studies how the sliding-gate valve (SGV) modifies the features and the dynamic behavior of the outlet jets for flat-bottom and well-bottom bifurcated submerged entry nozzles (SENs) used in continuous casting machines. Three conditions for the SGV were studied: no obstruction, moderate obstruction, and severe obstruction. The experimental study used a scaled model, employing cold water as the working fluid. A high-frequency analysis of the flow inside the SEN's bore arriving at the outlet ports was performed by employing the particle image velocimetry (PIV) technique. Low-frequency measurements of the volumetric flow at the exit port were obtained by splitting the exit jet into four quadrants and employing digital flowmeters. It was observed that reducing the SGV clearance increases the turbulence of the flow inside the SEN bore, but the flow displays ordered rather than erratic fluctuations. Flowmeter measurements showed that, regardless of the level of obstruction in the SGV, the outlet jets on flat-bottom and the well-bottom SENs have dynamic behaviors and features with significant differences. This finding is relevant because the flow distribution inside the outlet ports is directly related to the jet's wideness, affecting the recirculation pattern inside the mold and, therefore, the quality of the finished steel slab. [ABSTRACT FROM AUTHOR]

Silver reversible electrodeposition devices (SREDs) find wide applications in intelligent windows, automobiles, intelligent displays, and other fields. They can achieve a mirror state close to 100% reflectance and generate plasmon phenomena of different colors by controlling the driving voltage. However, the switchability of these devices is compromised below 0 °C due to the molecular properties of the solvent dimethyl sulfoxide (DMSO), making it impossible to work in severe cold areas. This work has discovered a solvent called N-methylpyrrolidone (NMP), which possesses weak intermolecular forces, low dipolarity, and high solubility. By developing a SRED using NMP as the solvent, we have achieved a lower opening voltage at room temperature compared to the DMSO system. This is advantageous for the preparation of large-area devices. Additionally, the NMP system device retains its switching ability even under extreme conditions of −40 °C, freezing only when temperatures reach −43 °C, which is currently the lowest reported SRED operating temperature. This breakthrough brings us closer to the practicality of SRED. [ABSTRACT FROM AUTHOR]

Cr12MoV die steel is frequently used for cold stamping, cold extrusion, and other cold work applications. However, surface defects such as micro-pits and micro-cracks are easily produced during the cutting process, which impacts the fatigue resistance of die. The formation mechanisms and influencing factors of various surface defects of hardened die steel are investigated by a combination of high-speed ball-end milling experiment and simulation. Results show that there are mainly five kinds of defects on the machined surface: micro-pits, micro-cracks, grooves, surface texture, and surface material residues. Micro-pit defects are formed when carbide particles are integrally pulled out, or broken and then spalled. When the carbide particles are large in size or have sharp edges, local microscopic stress concentrations will be generated between the sharp edges and the material matrix, causing micro-cracks within and around the spalled pits. The form of carbide particles spalling is changed from brittle spalling to plastic plowing under the effect of thermal softening, which causes the formation of groove defects. However, with the aggravation of thermal softening effect, machined surface is highly susceptible to extrusion and scraping from tool flank, which results in an increase in the number of defects and increasingly pronounced textural features. The research has important implications for improving the fatigue life of die and optimizing the cutting process parameters. [ABSTRACT FROM AUTHOR]

T8 treatment includes solution treatment, cold working and artificial aging treatment. T8 treatment can greatly improve the hardness and strength of 2024 aluminum alloy without reducing the corrosion resistance. The effect of 0, 1, 2, 3, and 4% cold-drawing deformation on the microstructures of the alloy was observed by transmission electron microscopy, and properties of the alloy was investigated by hardness tests, tensile tests and electrochemical corrosion tests. The results show that the mechanical properties and corrosion resistance of cold-drawing deformed 2024 aluminum alloy are better than those of non-deformed alloy. Compared with AA2024-T6, AA2024-T8 with 2% cold-drawing deformation has a higher hardness by 11.3%, and a higher tensile strength by 10.8%. The improvement of the properties of AA2024-T8 is mainly due to the interaction between dislocations and precipitates. With the increase in cold-drawing deformation, the nucleation points of precipitates in AA2024-T8 gradually increase, and precipitates are gradually coarsened under the same artificial aging treatment. [ABSTRACT FROM AUTHOR]

The Mogou site in Lintan, Gansu, has yielded the largest collection of Qijia culture bronze artifacts discovered to date. More than 300 bronze artifacts were unearthed, including new forms such as bracelets, neck ornaments, and earrings with trumpet-shaped ends, reflecting the advanced bronze production technology during the late Qijia culture period. This paper presents an analysis of 146 bronze artifacts from the Mogou site, conducted through metallographic microscopy and SEM-EDS analysis. Our results indicate that a relatively high percentage of small ornaments, primarily made of tin bronze, underwent hot forging and cold working, while tools, primarily made of copper and tin-bronze, were typically cast. Furthermore, this study reveals the concurrent existence of leaded tin bronze and arsenical bronze during the late Qijia culture period, suggesting influences from multiple metallurgical systems. [ABSTRACT FROM AUTHOR]

Burnishing is a well-known cold working technique for improving the surface integrity. It is cost-efficient and effective technique for enhancing surface finish as well as hardness. The use of burnishing to replace current heat treatment including grinding process on the reamer shank is offered as a unique strategy for reamer shank processing. This change in processing reduces cycle time and resources while also conserves energy required for processing during heat treatment and grinding. In this work, principal component analysis (PCA) is coupled with Taguchi optimisation technique to deal with multi-response problem to determine optimum parameter values of burnishing process to attain required surface finish and hardness in order to fulfill all functional requirements of shank. Test outcomes are convincing and show that suggested technique has ability to substitute current heat treatment along with grinding operation for reamer processing. [ABSTRACT FROM AUTHOR]

The "electron wind effect" has long been cited as a potential catalyst of solid-state transformations in metals, particularly when high current densities are involved. However, the literature exploring similar effects at lower current densities, such as those occurring during Gleeble thermomechanical simulation, remains scarce. The present work compares recrystallization activity in cold-rolled low-carbon steel during heat treatment by conventional furnace versus direct resistance heating (Gleeble). Multiple levels of cold work, annealing durations, and soak temperatures were examined, allowing for an in-depth comparison of recrystallization rates and activation energies between samples subjected to identical time–temperature profiles in the furnace and Gleeble. In addition to the expected increase in recrystallization behavior with the increases in temperature and cold-reduction levels, the use of the Gleeble system as the heating method resulted in faster initial microstructural transformation than a conventional furnace. The variability in recrystallized fractions persisted until the microstructures had saturated to their nearly fully recrystallized levels, at which point the microhardness and electron backscatter diffraction (EBSD) revealed convergence to equivalent behavior irrespective of the heating method. Analysis of the recrystallization kinetics by fitting to a JMAK relationship reflected the increased transformation activity during Gleeble treatment, with the value of the kinetic exponent also indicating greater grain growth activity at higher temperature. [ABSTRACT FROM AUTHOR]

In this study, the optimum values of pickling and annealing parameters in cold rolling were obtained by using the Taguchi method. The materials taken from the hot rolling mill were subjected to pickling with different pickling times (3 min, 4 min, 5 min) parameters and then cold rolled. After this process, annealing was carried out with different annealing temperatures (700 °C, 750 °C, 800 °C), annealing times (5 min, 7.5 min, 10 min) in order to eliminate the cold working hardness. After these processes, sheet materials were subjected to skin‐pass rolling, which is the last step of the rolling process. Optimum conditions are minimum rolling force measured from the load cell positioned on the work rolls. In this direction, S/N ratios with objective function "smaller is better" and were calculated and the optimum levels of the parameters were determined as 3 min pickling time, 750 °C annealing temperature and 10 min annealing time. In line with the findings obtained from the analysis of variance, it was determined that the most important parameter was the annealing time with a rate of 48.99 %. Confirmation experiments were carried out and it was concluded that the optimization was valid. [ABSTRACT FROM AUTHOR]

Due to the rising need for energy saving, high-performing automotive heat exchangers, demand has significantly grown in recent years. As a result, effective fin-tube heat exchangers are becoming more popular. These tubes are typically made by rolling flat strips of AA3003 aluminum alloys that have either one or both sides coated with AA4xxx alloys. The AA3003 type of alloy is typically used as the core, which is then covered in either AA4045 or AA4343, which melts during the brazing process to adhere the fins to the tubes. To maintain the optimal size and distribution of manganese (Mn)-containing precipitates, preheating parameters are carefully controlled. Then, longer soaking times or higher soaking temperatures result in larger precipitates, which cause the final product to exhibit poor mechanical properties. Therefore, it is crucial to optimize the different manufacturing steps, such as homogenization, soaking time, and brazing in order to achieve a high quality product. Studies on the impact of homogenization temperature and time on the microstructure of AA3xxx aluminum alloys have been conducted. However, there has been little research on the impact of soaking (reheating) time on AA3003 cladded alloys. Hence, the effects of isothermal soaking time on the microstructure and mechanical properties of AA3003 cladded with AA4045 alloy were investigated in this work. Optical microscopy (OM) and scanning electron microscopy (SEM) were used to characterize the microstructure and identify intermetallic phases. The final microstructure in terms of grain structure at various homogenization times was characterized by electron backscattered diffraction (EBSD). After the hot-rolling and cold-rolling of the as-received material, large particles of intermetallic (mainly in the form of Chinese script morphology consisting of Fe-Mn-Si) were broken into smaller particles with an increased Fe, Mn, and Si content, indicating the formation of an α-Al(Fe,Mn)Si phase. The α-Al(Mn,Fe)Si was found to be a dominant dispersoid precipitate in the modified AA3003 core. Coarsening of the Al(Mn,Fe)Si dispersoids at 505 °C was only observed at a 45 h homogenization time. The hardness trend with homogenization time was found to be similar to that after homogenization, cold working, and annealing, with exception of an increase in hardness in the latter possibly due to strain hardening (from cold-rolling). [ABSTRACT FROM AUTHOR]