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Ultra-fine grained bulk steel produced by accumulative roll-bonding (ARB) process
Abstract
Much attention has been directed recently to ultra-grain refining of metallic materials, where the grain size is reduced to less than 1 {micro}m. It is expected that submicrometer grained structure would result in high strength and toughness at ambient temperature as well as high strain rate or low temperature superplasticity at elevated temperatures. The authors have recently developed a novel intense straining process for bulk materials, named Accumulative Roll-Bonding (ARB). They firstly tried to apply ARB to the aluminum alloys, and the bulk sheets with ultra-fine grains whose grain sizes are several hundred nano-meters were successfully produced. The purpose of the present study is to clarify whether or not it is possible to produce the bulk steel sheets with ultra-fine grains by ARB process. Because steel is the most useful structural material, the ultra-grain refining of steel is greatly desired. The ultra-grain refining and resulted strengthening of steels could largely reduce the weight of any constructions, and the strengthening without alloying elements would be preferable for recycling. However, no investigation concerning the intense straining of bulk steels has been carried out by now possibly due to the difficulty in processing, although limited results about small materials, such as grain refining by powder metallurgical process (MM) or TS of thin discs, have been reported.
... Several SPD techniques have been developed, including torsion extrusion (TE), simple shear extrusion (SSE), equal channel angular pressing (ECAP), severe torsion straining (STS), and accumulative roll bonding (ARB). ARB developed by Saito et al. [7,8], has several benefits in comparison to other SPD processes. The ARB processing does not generate a significant amount of force, it is simple, it does not require dies, and it is very productive. ...
... It is clear that during ARB (Fig. 2a), the grains have a pronounced rolling elongation and also a relatively high aspect ratio. This results in the formation of a lamellar ultrafine-grained microstructure with a high density of dislocation substructures, which is typically called a pancake-shaped structure [7,8]. The SAD pattern is a ring like pattern consisting of separate spots, which indicated that the area has a large misorientation and a large number of grains with high angle boundaries. ...
... There are two types of dislocation boundaries: (i) incidental dislocation boundaries (IDBs), which form by statistical trapping of dislocations, and (ii) geometrically necessary boundaries (GNBs), which delineate regions that deform either with different slip systems or with a different strain partitioning on the same systems [33,34]. Misorientation angles increase for both types of boundaries at low strain, while GNBs can develop into high angle grain boundaries (HAGBs) [7,8]. As strain increases, the misorientations between the GNBs and IDBs increase, while the space between them decreases. ...
This study examined mechanical properties of AA2024 alloy and its correlation between strain path and crystallographic texture. Accumulative roll bonding (ARB) and cross accumulative roll bonding (CARB) were used to severely deform AA2024 alloys. Electron backscatter diffraction (EBSD) studies demonstrated that nano/ultrafine grains were formed by the strain routes after eight cycles. It was also found that the lamellar boundary spacing and the mean boundary spacing were ~ 360 ± 10 nm and 845 ± 10 nm after eight ARB cycles. In contrast to the ARB, the CARB specimen had equiaxed microstructures characterized by grains with a size of 150 and 100 nm. The CARB processed specimen exhibited a mean misorientation angle of 41.83° and a fraction of high angle grain boundaries of 78%, these values were 34.57° and 67% for ARB treated specimen, respectively. It was observed that the evolved texture is greatly affected by the strain paths. The ARB processed specimen revealed strong Copper {112} <111>, Dillamor {4 4 11} <11 11 8>, S {123} <634>, and Brass {011} <211> components. In contrast, the CARB processed specimen showed major texture with prominent Copper {112} <111>, Brass {011} <211>, Rotated Cube {001} <110>, S {123} <634>, and Goss {011} <100> components. In the CARB specimen, the Goss/Brass texture ratio was intensified and the mechanical properties were superior (tensile strength: 535 MPa, microhardness: 182 HV, elongation: 11.9%) compared with the ARB processed specimen (tensile strength: 455 MPa, microhardness: 145 HV, elongation: 9.2%). Further, the change in strain path did not significantly affect the intensity of Goss and Cube components, ruling out any further recrystallization tendency.Graphical Abstract
... In this method, an X-ray diffraction pattern is accurately matched with a series of structural parameters such as cell homogeneity, thermal motions, microstructural parameters such as sub-grain size, microstrain, peak shape, and background parameters. The variables are optimized and corrected by repeating the least-squares method and minimizing the residual parameters (Tsuji et al., 1999;Sahu et al., 2002;Dini et al., 2010). In Figure 9, the experimental XRD analysis image and the curve obtained from the MAUD software for the nine-cycle ARB sample are presented. ...
... These extremely small grains are polycrystals with relatively large mismatches relative to each other. It has been reported (Tsuji et al., 1999) that ultrafine grain boundaries produced by severe plastic deformation have non-equilibrium structures. An interesting result is that microstructural changes during ARB and ultrafine grains produced are almost similar for all materials and independent of the material type. ...
In this study, the accumulative roll bonding (ARB) method, a severe plastic deformation (SPD) process, was used to fabricate copper-2 wt% silicon carbide composite strips. The ARB process was successfully conducted for up to nine cycles on pure copper strips with silicon carbide particles distributed between them, as well as on monolithic copper. Equiaxed tensile and Vickers hardness tests were conducted to evaluate the mechanical properties of the samples. SEM was utilized to study the fracture surfaces and to determine the fracture mechanism of ARB processed monolithic copper and composite samples after the tensile test. Texture parameters were calculated through X-ray analysis. The Rietveld method using MAUD software were employed to assess the crystallite size of the samples. Results indicated that average amount of porosity decreased and interface bonding between copper strip layers improved with increasing the number of ARB cycles. Moreover, an increased number of cycles led to homogeneous distribution of SiC particles within the copper matrix. The tensile strength of the fabricated composites improved with an increase in the number of cycles, ultimately reaching 483 MPa after nine cycles, compared to 388 MPa for the composite processed with a single cycle of ARB and 194 MPa for annealed copper strips. Initially, the elongation of the composite samples decreased dramatically to about 6% after applying five cycle of ARB process from the 46% observed for annealed pure copper strip. However, it improved as the process continued, reaching 8.9% after the ninth cycle. Investigation of fracture surfaces after the tensile test using SEM revealed that the dominant failure mode was shear ductile fracture. Analysis of sample textures demonstrated that the dominant texture was (100). Crystallite sizes for pure copper and nine cycles-rolled composites, as determined by Reitveld method, reached 111 nm and 89 nm, respectively.
... The basic requirements are: first, to ensure that ultrafine grain (0.1-10 μm) structures with large angle grain boundaries can be obtained; second, it is necessary to produce great plastic deformation at normal atmospheric temperature; finally, the entire material must have a uniform ultrafine grain structure to ensure stable material performance (Valiev et al. 2000). Based on these principles, the main methods of SPD include high pressure torsion (Horita and Langdon 2008), equal channel angular pressing (Valiev and Langdon 2006), cyclic extrusion compression (Richert et al. 1999), repetitive corrugation and straightening (Huang et al. 2004), constrained groove pressing (CGP) (Shin et al. 2002;Krishnaiah et al. 2005), accumulative roll bonding (ARB) (Tsuji et al. 1999;Kwan et al. 2008), and so on. ...
The deformation rate in magnetic pulse forming is 100–1000 times higher than in quasi-static forming. This high deformation rate allows magnetic pulse forming to significantly expand the forming limits of metallic materials, resulting in notable improvements in both mechanical properties and microstructure. The impact deformation and grain refinement of panels subjected to magnetic pulses have been studied through experimental analysis and microstructure observations, with comparisons to constrained groove pressing. The following key findings were observed: The high-speed impact of magnetic pulses delays crack formation in the formed plates, increases the number of successful pressing cycles, leads to more uniform deformation, and enhances grain refinement. As a result, the application scope of magnetic pulse forming has been further expanded.
... Processing by SPD refers to the imposition of exceptionally high strains but without incurring any significant changes in the overall dimensions of the workpieces. Several different SPD processing routes are now available but the major techniques are equal-channel angular pressing (ECAP) [6,7] where a rod or bar is pressed repetitively through a die contained within a channel bent through a sharp angle, accumulative roll-bonding (ARB) [8][9][10][11] where a plate is rolled repetitively to one half thickness and then cut in half, degreased and wire brushed, stacked, and then rolled again and high-pressure torsion (HPT) [12][13][14][15] where a small sample, usually in the form of a disk, is subjected to a high pressure and concurrent torsional straining. In practice, HPT is especially attractive because it is a continuous process not requiring any additional labour within the straining operation. ...
High-pressure torsion (HPT) processing disrupts the thermodynamic equilibrium in immiscible systems and often produces nonequilibrium microstructures with unique properties. This study investigates the microstructural evolution and mechanical behaviour of a Cu-Nb immiscible alloy subjected to HPT under 6 GPa compressive stress. The HPT processing was performed on stacked Cu-Nb-Cu layers by up to 200 turns and this produced mechanically alloyed, homogenized disks free of porosity or cavities. Microstructural characterization using X-ray diffraction and scanning electron microscopy, coupled with energy-dispersive X-ray spectroscopy, revealed a stepwise evolution, including the reduction of segregation layers, the formation of nonequilibrium Cu-17 at%Nb solid solution in the disc processed at 200 HPT turns and an increased Nb insertion into the Cu lattice. Additionally, grain refinement and residual strain increments were observed with increasing torsional turns. Thereafter, the mechanical properties were evaluated using hardness mapping and tensile testing. The material exhibited strain hardening behaviour and achieved an ultimate tensile strength (UTS) exceeding 1.25 GPa. Following post-deformation annealing, the UTS decreased to ∼700 MPa due to recrystallization and recovery. These results provide a preliminary understanding of microstructural transformations and their impact on the mechanical properties of immiscible systems subjected to extreme deformation.
... By keeping the relative independence of Mg and Al alloys one can gain combined physical and chemical qualities in a single-layer material, as a layered composite laminate [4,5]. Laminate composites are prepared via various methods: hot-pressing, diffusion bonding, extrusion bonding, roll bonding, and powder metallurgy bonding [6][7][8]. However, Accumulative Roll Bonding (ARB) is widely preferred method for laminated composites because it is simple and requires minimal equipment, bonds dissimilar materials, produces ultrafine-grained structures, and also can be scaled up for industrial production [9][10][11][12][13]. ...
Light alloys play a crucial role in realizing the national strategy for energy conservation and emission reduction, as well as promoting the upgrading of manufacturing industries. Mg/Al composite laminates combine the corrosion resistance and ductility of aluminium alloy with the lightweight characteristics of magnesium alloy. The addition of Ce (rare earth elements) can improve the mechanical properties of magnesium via grain refinement and improve the ductility of the hybrid composites. In the present work, an investigation on addition of Ce into the Mg/Al matrix through Accumulative Roll Bonding (ARB) has been presented. The Mg/Ce/Al hybrid composite consists of Mg-4%Zn alloy and Al 1100 alloy with 0.2% Ce particles added between the dissimilar layers. The changes occurred in the evaluation of microstructure, corrosion and mechanical properties of the Mg/Ce/Al hybrid composite as a result of deformation process and also the addition of Ce have been explicated. The ARB parameters: temperature, rolling speed, percentage reduction, and aging time, have been studied. An increase of about 2.36 times in strength and hardness of the hybrid composite, has been reported. Further, the structure–property relations in the Mg/Ce/Al hybrid composites were aslo predict and compare using machine learning models: Decision Tree and Multi-Layer Perceptron (MLP) models.
... properties. [36]. The ARB technique involves a multi-stage, solid-state process. ...
Advancements in technology for the creation, characterization, modeling, design, and application of nanostructured materials are essential for maintaining competitiveness in the global industrial design and manufacturing market. Recently, processing extremely fine-grained metals through severe plastic deformation (SPD) techniques has reached a critical phase in development. Sufficient laboratory findings are available to demonstrate the overall viability of this approach, and it is widely acknowledged that these materials hold significant innovation potential.
The present work aims to conduct numerical investigations into the severe plastic deformation behaviors of metallic materials using both classical continuum and microscale approaches based on finite element method (FEM) simulations. Microscale analysis bridges the gap between continuum plasticity theory and the textural characteristics of metallic materials. By controlling the microstructural features and texture of metallic materials, it becomes possible to improve properties such as strength, fatigue resistance, resilience, and machinability.
Finite Element simulations typically utilize two types of algorithms for simulating metal forming processes: implicit and explicit. These processes involve geometric nonlinearities, material nonlinearities, and variable contact problems. The explicit solution technique offers particular advantages when analyzing large three-dimensional contact problems, making it applicable to metal forming simulations and providing simplicity in solving dynamic contact frictions.
An explicit crystal plasticity finite element method (CPFEM) model is developed to systematically understand the deformation behavior and texture evolution of single crystals and polycrystalline materials during full-scale SPD processes.
... Several techniques have been used to change the microstructure of low-carbon steels to enhance their hardness and strength. Tsuji et al. [5] used the accumulative roll bonding technique for low-carbon steel. The processed low-carbon steel by seven cycles revealed a high ultimate tensile strength (UTS) of 870 MPa, which was 3 times larger than that of the initial low-carbon steel sheet. ...
In the present work, the mechanical anisotropic behavior of low-carbon (Fe–0.07C) steel processed by asymmetric cold rolling was investigated. Three different types of dynamic recrystallization (DRX) mechanisms (continuous, discontinuous, and geometric) were observed in the microstructure of the 75 % cold-rolled sheet. The average intensity of γ-fiber was remarkably enhanced to 2.8 × R as rolling deformation increased to 50 % due to the formation of many deformation bands. After 75 % cold rolling, the average intensity of γ-fiber was significantly decreased to 1.4 × R due to the creation of new recrystallized grains. The results exhibited that the hardness of the low-carbon steel sheet was 260.1 HV by 75 % cold rolling, which was 1.75 times larger than the initial low-carbon steel sheet. With increasing deformation degree, the average yield and tensile strengths gradually improved and reached a peak value of 844.8 MPa and 881.7 MPa after 75 % cold rolling, respectively, which were 2.8 and 2.1 times that of the initial low-carbon steel sheet. By increasing the rolling reduction up to 50 %, the mechanical anisotropy gradually enhanced and by further increasing the cold deformation to 75 %, the anisotropy rapidly decreased due to the weakening of the γ-fiber texture. The strength was the highest along the transverse direction (90°) in all low-carbon steel sheets, and decreased at 0° and 45°. The dσ/dε–ε curves of the 50 % cold-rolled low-carbon steel sheet for the 45° and 90° tensile directions exhibited two distinct stages during the loading, however, that for the 0° revealed only one stage. A large number of parallel striations were present on the fracture surface of the 50 % deformed low-carbon steel sheet at 90° due to the presence of parallel deformation bands.
... ARB has demonstrated significant potential for enhancing mechanical properties such as strength, ductility, hardness and fatigue resistance. Recent times, experimental and simulation works have been conducted to understand the underlying mechanisms governing the mechanical behavior of ARB-processed materials, leading to the development of structure-property relationships [27,28]. ...
Accumulative roll bonding (ARB) is a severe plastic deformation technique commonly applied to produce ultrafine grain materials. ARB has evolved as a promising method in the last decade to produce aluminum matrix composites (AMCs) effectively, overcoming the common issues faced in various casting methods. This review summarizes the research works accomplished in producing AMCs using ARB and critically discusses the literature on each aspect. Homogenous distribution of reinforcement particles in the composite is exceptionally achieved in this process. The factors affecting the distribution, the breakage of particles and the grain size are critically reviewed and elucidated. The interfacial details and porosity issues are addressed. The difficulty in processing nano- and multiple particles to produce AMCs is explained. ARB provides high-strength composites. The underlying strengthening mechanisms for significant improvement in tensile, wear and corrosion properties are explained. ARB is recently applied as a secondary processing tool to improve the distribution and properties of cast AMCs. This aspect of ARB is further covered. The review concludes with applications, future development of this process and extensions to produce other metallic composites.
Graphical Abstract
... By employing low-cost thermo-mechanical approaches such as warm rolling (WR) [9-11] and accumulative roll bonding (ARB) [12-13], high-strength ultra-fine grained (UFG, with grain sizes ≤ 1 μm) bcc steels have been designed. Regrettably, UFG steels, despite their desirable DBTT, show compromised ductility, toughness, and low work-hardening capabilities at ambient temperatures [9][10][11][12][13]. To achieve high strength with reduced DBTT, Kimura et al. combined grain refinement with CRediT authorship contribution state ment ...
... To obtain nanocrystalline and ultrafine-crystalline structures, methods such as heat treatment [4][5][6], powder metallurgy [7], and sintering [8,9] have been adopted, which modulate cytological functions and extend the operational lifespan of medical devices [8][9][10][11][12][13][14][15]. While laboratory-scale severe plastic deformation methods such as equal channel angular pressing (ECAP) [15][16][17][18], accumulative roll bonding (ARB) [19][20][21], high-pressure torsion (HPT) [22][23][24][25], multiple compression [26], and upsetting extrusion [27] have shown success, they often compromise ductility, a crucial factor for biomedical device fabrication. A high strength-high ductility combination is necessary for a prolonged lifespan in any metallic device [28][29][30][31]. ...
The cytological behaviour and functional dynamics (adhesion, spreading, synthesis of proteins) of fibroblasts when interacting with biomedical surfaces are intricately influenced by the inherent nature of surface (nanocrystalline or microcrystalline), where the nanocrystalline (NC) surface is preferred in relation to the microcrystalline (MC) surface. This preference is a direct consequence of the distinct differences in physical and chemical characteristics between NC and MC surfaces, which include crystal boundary bio-physical attributes, electron work function, surface energy, and charge carrier density. The observed variances in cytological behaviour at the interfaces of NC and MC bio-surfaces can be attributed to these fundamental differences, particularly accounting for the percentage and nature of crystal boundaries. Recognising and understanding these physical and chemical characteristics establish the groundwork for formulating precise guidelines crucial in the development of the forthcoming generation of biomedical devices.
... Then, the plate is cut into two halves, which are stacked and then rolled again. This method results in good strength and elongation which can be used in the manufacturing of automobile equipment [5][6][7]. Due to the non-industrial nature and laboratory conditions of the production process, the production of large UFG plates is not possible in numerous industries, especially automotive, and aviation industries. Therefore, these nanostructured plates must be joined by welding or riveting methods. ...
... While there are several severe plastic deformation methods, multiaxial or multidirectional forging is viewed as a plastic deformation process that is generally believed to involve dynamic recrystallization and dynamic precipitation. UFG alloys are envisaged to exhibit outstanding cyclic stability together with a good combination of strength and ductility [1][2][3][4][5]. High strength and high ductility combination governs the formability of structural metals and alloys [6][7][8][9][10][11][12][13][14][15][16]. ...
Texture is an important aspect that impacts the formability of magnesium (Mg) and its alloys. Recently, the unique characteristics of multiaxial forging of Mg-2Zn-2Gd alloy were discussed, where it was demonstrated that multiaxial forged processed alloy is characterized by high strength and high ductility combination and the texture is significantly weakened or almost texture-free. The objective of the study described here is to obtain some fundamental insights that explain the underlying reasons for the weakening of texture in the multiaxial forged Mg-2Zn-2Gd alloy.
... The top-down approach is a method that decreases the grain size of coarse-grained alloy through severe plastic deformation (SPD) [119]. SPD methods include equal channel angular extrusion (ECAE) [120], accumulative roll bonding (ARB) [121,122], high-pressure torsion (HPT) [123], etc. Faleschini et al. analyzed the fracture behavior of tungsten alloys prepared by different preparation methods. The results indicated that the grain size of tungsten alloys prepared by the high-pressure torsion method was about 300 nm, and they exhibited excellent fracture toughness at room temperature [124]. ...
W-Re alloys are one of the most important refractory materials with excellent high-temperature performance that were developed to improve the brittleness of tungsten. In the present work, we firstly summarized the research progress on the preparation and strengthening methods of a W-Re alloy. Then, the strengthening mechanisms of the W-Re alloy were discussed, including the influence of Re, solid solution strengthening, second-phase reinforcement and fine-grain strengthening. The results showed that the softening effect of Re was mainly related to the transformation of the preferred slip plane and the introduction of additional d-valence electrons. Some transition elements and refractory metal elements effectively strengthened the W-Re alloy. Carbides can significantly enhance the high-temperature mechanical properties of W-Re alloys, and the reasons are twofold: one is the interaction between carbides and dislocations, and the other is the synergistic strengthening effect between carbides and Re. The objective of this work was to enhance the comprehension on W-Re alloys and provide future research directions for W-Re alloys.
... Proses SPD adalah proses pembentukan logam dengan regangan yang sangat besar dengan sedikit perubahan dimensi dimana regangan yang diberikan lebih besar dari 2.0 [2][3] . Beberapa proses severe plastic deformation (SPD) seperti accumulative roll bounding (ARB) [2][3][4][5] untuk lembaran logam, pengerolan pada suhu krio (cryorolling) 6) , high pressure torsion (HPT) 2) dan Equal Channel Angular Pressing (ECAP) [7][8][9][10][11][12][13][14] telah dapat menghasilkan butir dengan ukuran di bawah 1 m. ...
Telah dilakukan percobaan severe plastic deformation (SPD) dengan metodeequal channel angular pressing (ECAP) pada batang kuningan CuZn 70/30 diameter 10 mm sampai 5 pas. Gaya penekanan meningkat secara signifikan pada awal langkah penekanan dan mencapai nilai maksimum lalu melandai. Pada pas pertama gaya penekanan mencapai 115 kN, pas kedua 130 kN, pas ketiga mecapai 150 kN dan pada pas keempat 165 kN. Dari pengukuran luas area di bawah kurva gaya penekanan diperoleh energi total pembentukan pada proses ECAP batang kuningan persatuan panjang adalah 95 Joule/mm pada pas pertama, sampai 130 Joule/mm pada pas ketiga, dan turun 125 Juole/mm pada pas keempat. Secara kumulatif total energi persatuan panjang meningkat secara linier sesuai dengan peningkatan jumpah pas, dimana pada pas keempat mencapai 597 MPa. Peningkatan gaya penekanan dan energi penekanan sebanding dengan terjadinya peningkatan kekerasan pada batang kuningan dan terjadinya penghalusan butir. Kata kunci: ECAP, gaya penekanan, energi pembentukan, kekerasan, penghalusan butir, kuningan. Abstract Experiments of severe plastic deformation (SPD) have been carried out by the method of equal channel angular pressing (ECAP) on brass rods CuZn 70/30 diameter 10 mm to 5 pas. Pressing force significantly is increased emphasis on early steps and reaches a maximum value and then ramp. At the first pas the pressing force reached 115 kN, the second pass 130 kN, the third pass 150 kN and fouth pass is 165. From measurements of the area under the curve of pressing force, the total forming energy per unit length generated to form the brass rod in ECAP is 95 Joule / mm at the first pass, 130 Joules / mm at third pass and down to 125 Joule/mm at fouth pass. Cumulatively, the total forming energy per unit length increases linearly according to the increase in number of ECAP pass, where the fourth pass reach 597 Joule/mm. Increased emphasis pressing load and forming energy is proportional to the increase in hardness of the brass rod and the grain refinement. Keywords: ECAP, pressing load, forming energy, hardness, grain refinement, Brass
... A d v a n c e V i e w in SPD and HSMs fields, which have broadened their multidisciplinary applications and brought new underlying metallurgical knowledge. Regarding SPD, the development of new techniques, such as HPT, 37) ECAP, 38) ARB, 39) and RCS, 40) allowed the development of bulk nanograined (NG) and ultrafine-grained (UFG) arrangements. It's worth mentioning that while HPT research introduced the possibility of large shear stresses in confined systems, i.e., SPD as a new field, 41) the development of ECAP triggered its technological application as the first SPD technique with potential commercial use. ...
Heterostructured materials (HSMs) constitute heterogeneously distributed soft and hard zones with a mismatch in mechanical or physical properties of at least 100% between them. A synergistic effect resulting from the interactive coupling between the heterogeneous zones surpasses the properties predicted by the rule of mixtures. Therefore, the mechanical or physical properties of HSMs are not achievable by their homogeneous counterparts. HSM production commonly requires plastic deformation to refine the microstructure and subsequent partial recrystallization heat-treatments to obtain heterogeneous distributions of grain size, texture, or defect density. Other routes are by applying surface plastic deformation or by stacking layers with a high property mismatch between them. All of those routes can be achieved by severe plastic deformation (SPD) techniques. This overview focuses on describing the fundamentals of HSMs produced by SPD. A critical description of the physics of SPD and HSMs, as well as the factors influencing their microstructural evolution, perspectives, and outstanding issues, are included. A critical comparison of the strength–ductility relationship in HSMs produced by different SPD techniques is also included to guide upcoming research. This overview is intended to serve as a basis for understanding and designing future HSMs produced by SPD.
... There are several ways of producing ultra-fine-grained microstructures via severe plastic deformation strategies, such as accumulative roll bonding (ARB) ( Ref 12,13), equal channel angular pressing (ECAP) ( Ref 14,15), and highpressure torsion (HPT) (Ref [16][17][18]. But these techniques are not viable for developing the desired products on an industrial scale. ...
The low-carbon steel revealed the presence of ferrite-pearlite and ferrite-martensite microstructures after being subjected to different thermomechanical routes. These routes involved two distinct stages: 1) reheating hot-rolled steel at 1473 K, followed by cooling via step quenching, intermediate quenching, and furnace cooling, and 2) cold rolling and subsequently annealing at 873 K for 2 and 8 h. The quenching schedules finally developed a ferrite-martensite structure with different martensitic morphology, whereas furnace cooling promotes a ferrite-pearlite structure. The prolonged annealing assists in carbide precipitation from deformed ferrite-martensite microstructure while pre-existing carbides coarsen after 8 h of annealing in furnace-cooled specimens. The sudden phase disintegration contributes to the changes in the recrystallized kinetics and evolution of precipitates, tailoring the final grain size. Additionally, the development of textures after cold rolling and annealing is studied through the emergence of α and γ fiber in BCC phase. Finally, detailed microscopic technique has been employed to correlate the overall tensile response of the investigated samples with their interrelated microstructures.
... The outcome of this technique is often a product that contains the proper level of strength and ductility compared with the conventional rolling process. The technique can therefore be used to produce lightweight automotive products and advanced materials for high-technology industries [6]. Due to the inherent limitations of the production of nanostructured sheets for automotive and aerospace industries through conventional rolling processes, where large-size sheets are required, the joining techniques of the UFGs ARB-produced sheets are of significant prominence. ...
In this investigation, the dissimilar ultrafine-grained (UFG) composite of AA2024 and AA5083 was made using four cycles of accumulative roll bonding (ARB). The composite was then welded by the friction stir welding (FSW) method. Using the Taguchi technique , welding parameters of tool rotational speed, welding speed, pin geometry, and tool tilt angle were optimized. Optical microscopy, Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) were used to study microstructural evolution in the ARB processed specimen, as well as in the stir zone (SZ), thermo-mechanically affected zone (TMAZ) and heat affected zone (HAZ). Taguchi optimization showed that a Square pin, with a rotational speed of 655 rpm, welding speed of 110 mm/min, and tool tilt angle of 3 were the optimum welding process parameters. The microstructural assessment showed that the SZ consisted of a recrystallized microstruc-ture with an average grain size of about 900 nm. Tensile strength was reduced from 667 MPa in the ARB-processed sample to 403 MPa in the optimized FSW condition. However, yield strength was slightly reduced due to the ultrafine-grains of the weldment. The relatively high strength of the composite was due to solid solution, grain boundaries strengthening, and nano-sized Al 20 Cu 2 Mn 3 precipitates (T-phase) formation. The presence of precipitates led to a proper level of ductility of up to two times in the FSW structure compared to the UFG structure. The highest mean hardness of the weldment, ~132 HV, was obtained which was due to the grain refinement, dislocation generated by the pin movement, and small-size precipitates.
In this study, microstructure, corrosion behavior, and tribological properties of Cu–GO nanocomposites produced by accumulative roll bonding (ARB) process up to 4 cycles have been studied through microstructure observation, microhardness testing, pin-on-disk wear-testing, and electrochemical measurements in 3.5-wt pct NaCl solution. Microstructural studies show ARB can remarkably decrease the grain size and improve the dispersion of GO in the Cu matrix as well as the connection improvement between Cu layers. It is observed that the highest hardness value of about 140 HV is obtained with the increasing number of cycles up to 4 due to the strain-induced grain refinement and presence of secondary phase GO. Moreover, wear rate and weight loss of the samples were continuously decreased up to cycle 2 and after that they were grown and delamination wear became the dominant mechanism with increasing the ARB cycles. In addition, corrosion behavior shows that the corrosion current density (0.7 × 10−3 A cm−2) of the nanocomposite was decreased after 4 cycles and the best anti-corrosion property for forming the passive films was provided. The coarse microstructure in Cu-annealed sheet leads to accelerating galvanic corrosion.
This article investigates the forgeability of a microalloyed steel 0.18C-1.38Mn-0.36Si-0.47Cr-0.03Mo-0.05Al-0.04Nb-0.01Ti, with emphasis on its application in the hot forging process followed by continuous cooling, aiming to eliminate traditional quenching and tempering heat treatments. The research seeks to understand how thermomechanical parameters influence the microstructure and material behavior during processing. The approach included experiments and numerical simulations, as well as detailed analysis of the prior austenitic structure. The wedge test was employed to correlate microstructural changes with deformation under different temperatures. The results show that controlled deformation, combined with high forging temperatures, promotes recrystallization and grain refinement, resulting in a uniform bainitic microstructure and high hardness levels. The steel showed potential for application in small-volume parts, offering a cost-effective and energy-efficient solution by eliminating the need for heat treatments.
At present, the emerging solid-phase friction-based additive manufacturing technology, including friction rolling additive manufacturing (FRAM), can only manufacture simple single-pass components. In this study, multi-layer multi-pass FRAM-deposited aluminum alloy samples were successfully prepared using a non-shoulder tool head. The material flow behavior and microstructure of the overlapped zone between adjacent layers and passes during multi-layer multi-pass FRAM deposition were studied using the hybrid 6061 and 5052 aluminum alloys. The results showed that a mechanical interlocking structure was formed between the adjacent layers and the adjacent passes in the overlapped center area. Repeated friction and rolling of the tool head led to different degrees of lateral flow and plastic deformation of the materials in the overlapped zone, which made the recrystallization degree in the left and right edge zones of the overlapped zone the highest, followed by the overlapped center zone and the non-overlapped zone. The tensile strength of the overlapped zone exceeded 90% of that of the single-pass deposition sample. It is proved that although there are uneven grooves on the surface of the overlapping area during multi-layer and multi-pass deposition, they can be filled by the flow of materials during the deposition of the next layer, thus ensuring the dense microstructure and excellent mechanical properties of the overlapping area. The multi-layer multi-pass FRAM deposition overcomes the limitation of deposition width and lays the foundation for the future deposition of large-scale high-performance components.
Defect-free sound joints of high-phosphorus (0.094 wt.%) weathering steel (SPA-H) were successfully fabricated using friction stir welding (FSW). This study examines the microstructural evolution and mechanical properties of joints produced at different FSW parameters. Tensile tests of the joints revealed that fractures occurred in the base metal (BM) region, indicating almost 100% welding efficiency. Furthermore, the stir zones (SZ) demonstrated a marked improvement in tensile properties. Particularly, at the rotation rate of 80 rpm and axial load of 45 kN condition (below A1), the microstructure featured ultra-fine ferrite and cementite, resulting in high hardness (270 HV) and tensile strength (704 MPa) in steel with just 0.08 wt.% C, while maintaining nearly 80% of the total elongation of BM. However, the SZ at 80 rpm exhibited an unusual decrease in local elongation despite the fine ferrite grain size and cementite presence. Electron probe microanalysis (EPMA) and nano-hardness revealed pronounced phosphorus segregation in the ferrite region and significant localized hardness disparities induced by the segregation behavior. The strain concentration at the interfaces between these regions during the tensile process leads to crack initiation and rapid propagation. The negative factor caused by the phosphorus segregation accelerates the failure of the specimen during the necking stage and ultimately shows decreased local elongation.
In this study, the Accumulative Roll Bonding (ARB) technique was used to develop an aluminum alloy with an exceptionally refined grain structure. By examining the materials after various ARB cycles, we observed notable improvements in their mechanical properties. X-ray diffraction revealed a significant reduction in crystallite size from 29 nm to 19 nm after five passes through the ARB process. This refinement corresponded with remarkable increases in both yield and ultimate tensile strength, with the yield strength improving by 113% and tensile strength by 60% compared to the original alloy after the fifth pass. Microhardness testing showed a substantial 40% increase, reaching a hardness value of 73.3 HV. Optical microscopy of the roll-bonded Al5052 alloy sheet displayed ductile shear rupture characterized by elongated shear dimples. These findings clearly demonstrate that the ARB process is highly effective in producing an ultra-fine-grained aluminum alloy with significantly enhanced mechanical properties.
Grain refinement and mechanical property enhancement of cast ingot aluminum 6061 alloy were achieved using equal-channel angular pressing (ECAP) at room temperature, employing route A and route R types. Analytical, finite element and experimental methods were utilized to investigate the alloy’s deformation behavior under the ECAP process. The tensile tests conducted at room temperature demonstrated a significant increase in strength with an increasing number of pressings, reaching 44.23, 53.19, and 56.7% for 1-pass, route A, and route R types 2-passes of the ECAP process, respectively. However, ductility, as indicated by elongation, gradually decreased after the first pressing. Electron backscatter diffraction was employed to reveal submicrometer grain sizes resulting from the ECAP process. The grain structure showed substantial improvement under route A and route R types at a 2-passes ECAP process. Wear tests conducted under loads of 10 and 25 N showed an increase in the coefficient of friction within the minimum wear loss intervals. Rockwell hardness also exhibited a significant increase of 119.3, 176.3, and 164.8% at 1-pass and 2-passes using routes R and A, respectively. As part of the evaluation, analytical models were computed using Python, and finite element simulations were performed using ABAQUS software. The results from analytical and finite element simulations demonstrated good agreement with the experimental data.
The texture and hardness of high purity aluminum single crystals that have been deformed by recurrent biaxial compression were investigated. Three types of specimens, WW, BW, and RR, were prepared using a modified Bridgeman method. The two compression axes were［100］and［0-10］in WW,［ 101］and［0-10］in BW, and［596］ and［15 -11 4］in RR. The specimens were deformed along one compression axis under plane strain conditions at a strain of 0.25, and then they were deformed along the other axis at the same strain conditions. Biaxial compressions up to eight times were repeatedly performed, for which the cumulative strain was 2. The textures of all the specimens after eight biaxial compressions showed that the average crystal orientations were within approximately 15° relative to the initial orientations. Textures were formed because of the forward/inverse slips of identical active slip systems during biaxial compression. The hardness tests of the three specimens indicated an obvious dependency on initial orientation. The WW specimen exhibited the lowest hardness value, which was ascribed to the occurrence of cross slips that continued for the eight biaxial compressions.
Due to the supply problems and welding problems experienced in high-strength steels and the fact that the use of thicker sheets increases the weight of the ship, using low-strength steels by increasing their strength with severe plastic deformation methods (SPD) without changing their chemical content is seen as a good alternative. Among the SPD methods, friction stir process (FSP) stands out in terms of its applicability to plate type materials. On the other hand, it seems that there is no study in the literature on applying this process to shipbuilding steels and calculating the ultimate strength of the ship section by transferring the material properties to a finite element-based model after the FSP. In this context, the aim of the study is to reveal the effect of FSP on mechanical properties and the effect of the change in mechanical properties on the ultimate strength of a produced ship section. So, in the study, FSP was applied to ship steel and the changes in the microstructure and mechanical properties of the steel were determined. As a result of the examinations, it was determined that grain refining occurred in the steel after FSP and as a result, the hardness, strength and formability forces of the steel increased. In addition, the changes in the mechanical properties of the steel were transferred to the ship bottom section created with a finite element-based program, and the ultimate strength values in this section were examined comparatively for the base material and the FSPed material. With examinations, it was determined that the ship section’s ultimate strength values were higher in the model created with FSPed steel.
This study investigates the enhancement of mechanical properties and changes in microstructure in a 6061
aluminum alloy processed through accumulated roll bonding (ARB), a severe plastic deformation process
that generates ultra-fine grains. The ARB process was performed without lubrication at an elevated
temperature (500 °C) for a maximum of five cycles. After the third cycle, distinct boundaries and ultra-fine
grains (UFG) with a crystallite size of 30 nm were observed, which were further reduced to 17 nm after the
fifth cycle. After undergoing five ARB cycles, the 6061 alloys exhibited a significant increase in tensile
strength, reaching approximately 2.6 times their original value. However, elongation experienced a sig-
nificant decrease following the first cycle and gradually decreased with subsequent cycles. Regarding
hardness, the specimens subjected to one, three, and five cycles exhibited uneven variations along the
normal direction, with non-uniform fluctuations. Notably, peak values were observed near the surface and
at the center of the specimens. Wire brushing and shear strain were identified as the causes of this uneven
hardness distribution. These findings suggest that the ARB method effectively refines and strengthens the
grain structure of the Al6061 alloy.
Ultrafine-grained and heterostructured materials are currently of high interest due to their superior mechanical and functional properties. Severe plastic deformation (SPD) is one of the most effective methods to produce such materials with unique microstructure-property relationships. In this review paper, after summarizing the recent progress in developing various SPD methods for processing bulk, surface and powder of materials, the main structural and microstructural features of SPD-processed materials are explained including lattice defects, grain boundaries and phase transformations. The properties and potential applications of SPD-processed materials are then reviewed in detail including tensile properties, creep, superplasticity, hydrogen embrittlement resistance, electrical conductivity, magnetic properties, optical properties, solar energy harvesting, photocatalysis, electrocatalysis, hydrolysis, hydrogen storage, hydrogen production, CO2 conversion, corrosion resistance and biocompatibility. It is shown that achieving such properties is not limited to pure metals and conventional metallic alloys, and a wide range of materials are currently processed by SPD, including high-entropy alloys, glasses, semiconductors, ceramics and polymers. It is particularly emphasized that SPD has moved from a simple metal processing tool to a powerful means for the discovery and synthesis of new superfunctional metallic and nonmetallic materials. The article ends by declaring that the borders of SPD have been extended from materials science and it has become an interdisciplinary tool to address scientific questions such as the mechanisms of geological and astronomical phenomena and the origin of life.
The mechanical characteristics of polycrystalline metallic materials are influenced significantly by various microstructural parameters, one of which is the grain size. Specifically, the strength and the toughness of polycrystalline metals exhibit enhancement as the grain size is reduced. Applying severe plastic deformations (SPDs) has a noticeable result in obtaining metallic materials with ultrafine-grained (UFG) microstructure. SPD, executed through conventional shaping methods like extrusion, plays a pivotal role in the evolution of the texture, which is closely related to the plastic behavior and ductility. A number of SPD processes have been developed to generate ultrafine-grained materials, each having a different shear deformation mechanism. Among these methods, linear twist extrusion (LTE) presents a non-uniform and non-monotonic form of severe plastic deformation, leading to significant shifts in the microstructure. Prior research demonstrates the capability of the LTE process to yield consistent, weak textures in pre-textured copper. However, limitations in production efficiency and the uneven distribution of grain refinement have curbed the widespread use of LTE in industrial settings. This has facilitated the development of an improved novel method, that surpasses the traditional approach, known as the nonlinear twist extrusion procedure (NLTE). The NLTE method innovatively adjusts the channel design of the mold within the twist section to mitigate strain reversal and the rotational movement of the workpiece, both of which have been identified as shortcomings of twist extrusion. Accurate anticipation of texture changes in SPD processes is essential for mold design and process parameter optimization. The performance of the proposed extrusion technique should still be studied. In this context, here, a single crystal (SC) of copper in billet form, passing through both LTE and NLTE, is analyzed, employing a rate-dependent crystal plasticity finite element (CPFE) framework. CPFE simulations were performed for both LTE and NLTE of SC copper specimens having <100> or <111> directions parallel to the extrusion direction initially. The texture evolution as well as the cross-sectional distribution of the stress and strain is studied in detail, and the performance of both processes is compared.
The phenomena in solid-state welding (SSW) of metals during accumulative roll bonding (ARB) are analysed. The basic mechanism in SSW is described by the ‘film theory’, where superficial oxide layers/cover layers of metals fracture when submitted to elongations, the material on both sides of the sheets to be joined are extruded through these fractures and opposing virgin surfaces touch and weld. Present results reveal new aspects of these phenomena: the presence of ‘mountain ridges’ on delaminated surfaces after ARB, bonding regions along the rolling direction and the flattening of the geometric characteristics of delaminated surfaces as the number of ARB passes rises. A model is proposed for the development of the bonds along the rolling direction.
A rapid heavy warm rolling (HWR) process was adopted to fabricate medium-carbon low-alloy (<2.0 wt.%) martensitic steels with ultra-fine lamellar structure (ULS) suitable for industrial applications. The microstructure of the ULS martensite was mainly characterized by ultra-fine lamellae comprised of only aligned laths with reduced martensitic variants. Numerous nanoprecipitates were introduced and dispersed uniformly within the matrix after the HWR process without any tempering treatment. The density of dislocations increased dramatically to 6.694 × 1015 m−2 in ULS martensite due to the HWR process and martensitic phase transformation. Moreover, dispersed ultra-fine retained austenitic phases were embedded within the ultra-fine martensitic matrix and along martensitic boundaries, which led to an excellent combination of ultra-high ultimate yield strength of ~ 1.9 GPa, tensile strength of ~ 2.8 GPa and great elongation of ~ 6.4%. The present rapid HWR process provides a feasible method for improving the ultra-high strength and excellent ductility of martensitic steels.
Superplasticity requires a very fine grain size, typically in the range of ≈1-10 μm. Experiments have established that even finer grain sizes, in the submicrometer and nanometer range, may be achieved in metals by using an intense plastic straining technique such as equal-channel angular (ECA) pressing. This paper examines the microstructural characteristics and the stability of two different aluminum-based alloys subjected to ECA pressing: an Al-3% Mg solid solution alloy and a commercial Al-5.5% Mg-2.2% Li-0.12% Zr alloy containing a fine dispersion of δ' Al3Li and β' Al3Zr precipitates.
Some ultrafine-grained materials produced by severe plastic deformation were studied and compared to literature results for those obtained by other processes. In particular, comparisons between various as-prepared microstructures and between their evolutions during heat treatments were conducted. It was found that the high internal elastic strains probably arises from a metastable state of grain boundaries. Recovery of such microstructures occurs first by grain boundary recovery and by grain growth. The high level of internal elastic strains as well as the very fine scale of the microstructure should play an important role in the unusual mechanical behaviour of ultrafine-grained materials.
The introduction of an ultrafine-grained (UFG) structure into metals and ceramics provides the possibility of achieving high superplastic-like tensile ductility at lower temperatures and/or faster strain rates. However, there are problems associated with the nature of the grain boundaries in UFG materials. Recent work on UFG metals and ceramics is examined with special emphasis on the characteristics of the grain boundaries and the influence of these boundaries on the mechanical properties of the materials. Difficulties arise in UFG metals because of the presence of non-equilibrium grain boundaries, whereas in UFG ceramics, such as yttria-stabilized tetragonal zirconia, there are complications because of the possible presence of an amorphous boundary phase.
The high strain powder metallurgy (HS-PM) process, which is a novel and the most efficient non-equilibrium powder metallurgy process, is applied to an SUS 316L austenitic stainless steel. The HS-PM process is a powder metallurgy process combining mechanical milling, heat treatment and sintering processes, and enables one to produce an ultra-fine grain structure. In the case of the SUS 316L stainless steel, room temperature recrystallization and recovery of an austenite phase take place because of the increased high angle grain boundary area and the existence of excess vacancies, which are stored during the milling process. Very fine ferrite grains are formed in the early stage of the milling and an ultra fine (α+γ) microduplex structure is formed at the end. In the case of higher energy milling, almost fully ferritic nanograin structure with an average grain size of approximately 20 nm is formed. The ultra fine (α+γ) microduplex structure in the HS-PM processed powder accelerates precipitation of σ phase in the sintering process. The sintered compacts with a very fine (γ+σ) microduplex structure show an extremely high strength, i.e., more than three times higher 0.2% proof stress than the annealed parent material, without any severe depression in the elongation.
The behavior of work-hardening which occurs during mechanical milling (MM) treatment in metallic powders, and the process of recovery and recrystallization which occurs during annealing in the MM powders were over-viewed showing the results obtained by the authors using an industrial pure iron powder. Through the MM treatment, metallic powders stores extremely large strain energy, and this results in the marked work-hardening and the formation of a fine structure with nanocrystalline grains. In the case of iron, the hardness of powder can be increased to DPH1024 in practice, and the crystalline grain size is to be reduced to the limiting value of 3.4 nm in principle. The polycrystallization of dislocation cells and subgrains also proceeds on the grain refining process. When the MM powders are annealed, the powders undergo different microstructural changes depending on the degree of work-hardening subjected by the prior MM treatment. In the case that powders are not work-hardened so much, usual recovery and recrystallization occur with raising annealing temperature. However, when powders are extremely work-hardened to the level where crystalline grain size nearly reaches the limiting value, only the process of normal grain growth occurs during annealing and this results in the softening of MM powders. Under the usual milling conditions, the degree of work-hardening of powders is in the middle stage, so that both of the above two processes are possible with overlapping each other. It was confirmed in both of MM iron powders and annealed iron powders that the relation between hardness and polycrystalline grain size gives a good fit to the Hall-Petch relationship in a wide grain size range up to 6 nm. In addition, some examples are introduced at the end, in order to excellent properties of materials produced from MM powders.
Mechanical behavior and structural changes, such as the evolution of grain and dislocation structures and the formation of slip lines and grain-boundary-sliding traces, of a submicron-grained (SMG) copper during room-temperature compression have been studies. It is suggested that the absorption of dislocations into grain boundaries (GBs) is due to the migration and sliding of some highly non-equilibrium GBs during the deformation process and is influenced by high level internal stresses. From this point of view, the unusual behavior of SMG copper, in particular, the high yielding and flow stresses, the absence of strain hardening, high plasticity and low strain rate sensitivity, are explained. Analogies of the mechanical behavior of SMG copper with mechanical properties of metallic materials at large plastic strains in stage 4 are discussed.
An Al-3% Mg solid solution alloy was subjected to intense plastic deformation, using either equal-channel angular (ECA) pressing or torsion straining, to produce grain sizes in the submicrometer range. Static annealing at elevated temperatures led to grain growth and average grain sizes of up to > 100 μm. As-fabricated and statically annealed specimens were used to determine the variation in microhardness with grain size, and results confirm that the Hall-Petch relationship persists down to at least the finest grain size examined experimentally (∼90 nm). The results provide no evidence to support the claims of a negative Hall-Petch slope when the average grain size is very small, but there is evidence of a decrease in the slope of the Hall-Petch plot at the very finest grain sizes (
Structural evolutions in an Armco iron subjected to severe plastic deformation by torsion under high pressure are analyzed with conventional and high resolution electron microscopes. The substructure observed at low strains appears to shrink with increasing deformation and transforms at very high strains into grain boundaries. The resulting grain size decreases down to a constant submicrometric value. Meanwhile, the material strength, as revealed by micro hardness measurements, levels out. Dislocation densities and internal stress levels are used to discuss the structural transformations. Hydrostatic pressure and deformation temperature are believed to modify the steady-state stress level and structural size by impeding the recovery processes involving diffusion.
The recent situation of IF steel is reviewed and discussed with regard to following items: 1) The production of IF steel in Japan, 2) Featuring conditions to decarburize the molten steel effectively in steelmaking process, 3) The effect of Ti and Nb on metallurgical behaviors of IF steel, 4) The effect of processing conditions on metallurgical properties of IF steel, 5) The effect of soluted carbon on the powdering and the cold working embrittlement of IF steel, and 6) Metallurgical properties of IF ferritic stainless steel.
High-resolution electron microscopy was used to examine the structural features of grain boundaries in Al–1.5% Mg and Al–3% Mg solid solution alloys produced with submicrometer grain sizes using an intense plastic straining technique. The grain boundaries were mostly curved or wavy along their length, and some portions were corrugated with regular or irregular arrangements of facets and steps. During exposure to high-energy electrons, grain boundary migration occurred to reduce the number of facets and thus to reduce the total boundary energy. The observed features demonstrate conclusively that the grain boundaries in these submicrometer-grained materials are in a high-energy nonequilibrium configuration.
This letter is concerned with the investigation of some peculiarities of highly-strained magnesium alloy structure and regularities of subsequent recrystallization process leading to the formation of an SMG structure
Strain-heat methods of obtaining ultrafine-grained (UFG) metallic materials with grain sizes as small as 20 nm and peculiarities of their structure are considered. It is shown that intercrystalline boundaries are the main element of the structure of UFG materials and that they are typically in a non-equilibrium state. The formation of a special grain boundary phase, i.e. a thin near-boundary layer with high dynamic activity of atoms, has been found. This unusual structure leads to the manifestation of promising new elastic, strength, superplastic, damping and magnetic properties of UFG materials.
The peculiarities of a submicron-grained structure formation in a series of aluminium- and magnesium-based alloys by means of a special strain-heat treatment are examined in this paper. The unusual mechanical properties of alloys displayed in this state at room temperature as well as at enhanced temperatures are found. The nature of the plastic deformation of these materials is discussed.
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