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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.

Abstract We created AA2024–AA1050 and AA2024–AA1050/0.005 vol.% Al2O3 nanocomposites by six accumulative roll bonding (ARB) process cycles. We used AA2024 and AA1050 sheets with a thickness of 0.7 mm and plate-shaped alumina nanoparticles to create a composite. The two AA1050 and one AA2024 sheets (among the two AA1050 sheets) were ARB-ed up to six cycles with and without adding alumina nanoparticles. Also, a sample of the AA1050 without composite making was ARB-ed up to six cycles. We aged some composites after the ARB process in the furnace at 110, 150, and 190 °C. This project performed SEM, TEM, and EDS-MAP analyses, tensile strength, microhardness, and Pin-on-Disc tests to study the ARB-ed sheets. The results of the tensile tests showed that the tensile strength of AA2024–AA1050 created by the six cycles ARB process was two times more than primary AA1050. Also, the wear resistance of this composite was 74% more than six cycles ARB-ed the AA1050. Using 0.005 vol.% alumina nanoparticles in AA2024–AA1050 composite improved its wear resistance by 30%. In the following, the aging process caused an improvement in tensile strength and total elongation of AA2024–AA1050/Al2O3 nanocomposites.

In this study, graphene reinforced Inconel 718 composites were produced using a novel hybrid accumulative roll bonding (ARB)–gas tungsten arc welding (GTAW) and the mechanical and wear resistance of the composite were assessed. The microstructure characterization was studied by XRD, SEM, TEM and Raman spectroscopy. The results display that GTAW approach was a sustainable way to produce Inconel 718 based composite while addition of graphene nanoplatelets (GNPs) leads to a substantial improvement in strength of superalloy matrix, as well as the wear performance enhancement. Both yield strength and tensile strength of composite specimen with 1.0 wt% GNPs was 35% and 45% higher than those of base Inconel material, and the friction coefficient and wear rate were 204% and 52% lower than those of non-reinforced Inconel 718. Such enhancement of tribological properties can be ascribed to the hardness increase of GNPs–containing specimens and the formation of GNPs protecting film on the worn exteriors.

This study investigated the microstructure, texture, and mechanical properties of 1050 aluminum alloy sheets that underwent the accumulative roll bonding (ARB) method. The ARB proceeded up to eight passes in three ways: conventional process, preheat between rolling passes (preheating) or anneal between rolling passes (annealing). Heat treatment was done between the ARB passes for 5 min at 150 °C. The mean grain width of the 1050 Al sheet that was 11 μm before ARB, decreased to 295.73 nm, 317.33 nm, or 339.23 nm after six ARB passes in the conventional process, annealed or preheated conditions, respectively. Concurrent heat treatments cause a decrease in the strength of the texture components of Al sheets that were elaborated by the ARB method. Even though conventional and annealed processes successfully enhanced the microhardness by ∼80% and tripled the tensile strength, these improvements were weaker in the preheated condition than the other conditions due to dynamic recovery.

In this study, we successfully obtained a 2Mg-Fe mixture through mechanical alloying (MA) and processed it via accumulative roll bonding (ARB) (MA+ARB). Our primary focus was to analyze the impact of ambient air exposure while also evaluating the processing route. Some powder samples were exposed to air for 12 months (stored in a glass desiccator with an average yearly temperature and relative humidity of ~27 °C and 50.5%) before undergoing ARB processing. The Mg samples obtained after ARB processing exhibited a (002)-type texture. Our results demonstrate that all samples, including those processed via ARB, could rapidly absorb hydrogen within a matter of minutes despite considerable differences in surface area between powders and rolled samples. Grain size reduction by MA and ARB processing and texturing may have influenced this behavior. ARB-processed samples reached approximately 60% (~1.8 wt.%) of their maximum acquired capacity within just 24 min compared to powders (~2.2 wt.%) stored for a year, which took 36 min. In addition, the desorption temperatures (~300 °C) were lower than those of MgH2 (~434 °C). The absorption and desorption kinetics remained fast, even after prolonged exposure to air. Although there were minor variations in capacities, our overall findings are promising since scalable techniques such as ARB have the potential to produce hydrogen storage materials that are both safe and cost-effective in a highly competitive market.

A multiple processing technique that combines cold spraying (CS) and accumulative roll bonding (ARB) was designed to prepare multilayered 1060Al/Al–Al2O3 composites with improved ductility. Microstructural evolution during processing was characterized using scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD). The deposited Al–Al2O3 complex layer was well bonded to the 1060Al matrix, and during ARB processing, the deposited layers were highly squeezed to eliminate voids, Al2O3 particles were split to reduced size and dispersed to a homogeneous distribution within the deposited layers. The tensile test results revealed that the best combination of strength and ductility was achieved in the sample with optimized 3-pass ARB processing, with an increase of ∼41.66% in ultimate tensile strength (153 MPa) and an increase of ∼95.73% in tensile elongation (7.34%) compared to the initial As-Annealed sample. Fracture behavior of the prepared composite was also analyzed. The analysis of microstructural features provided insight into the underlying mechanisms explaining the high strength and great ductility.

Ultrafine-grained Cu/Al/Ag composites were processed by an accumulative roll bonding (ARB) technique from pure copper and aluminum sheets and a silver powder. The Al content was fixed to 11 wt.% while the silver concentration was 1, 2, or 3 in wt.%. The ARB-processed samples were heat treated at different temperatures between 750 and 1050 °C for 60 min and then quenched to room temperature (RT) for producing Cu–Al–Ag alloys. The effect of the addition of different Ag contents and various heat treatment temperatures on the structural evolution was investigated. The ARB-processed samples were composed of Cu and Al layers with high dislocation density and fine grain size (a few microns). During heat treatment of the ARB-processed samples, new intermetallic phases formed. For the lowest Ag content (1 wt.%), the main phase was a brittle simple cubic Al4Cu9, while for higher Ag concentrations (2 and 3 wt.%), the quenched samples contain mainly an orthorhombic β1-AlCu3 martensite phase. The martensite phase consisted of very fine lamellas with a thickness of one micron or less. The heat treatment increased the microhardness and the strength of the samples at RT due to the formation of a fine-grained hard martensite phase. For 2 and 3% Ag, the highest martensite phase content was achieved at 850 and 950 °C, respectively. The annealed and quenched samples exhibited good shape memory behavior at RT.

In the present work, nano/ultrafine structured Al/Brass composite was produced by accumulative roll bonding (ARB) up to eight cycles. The evolution of grain refinement and deformation texture and their effect on the mechanical properties were investigated. It was observed that by increasing the ARB cycles, due to the difference in flow properties of the metal constituents, brass layers necked, fractured and distributed in aluminum matrix. After eight cycles, a composite was produced with almost homogeneous distribution of brass fragments in aluminum matrix. Microstructural characterization by electron backscatter diffraction (EBSD) revealed the formation of bimodal structure consisting of equiaxied grains with an average size of ~120 nm and elongated grains after eight cycles, which was attributed to the occurrence of redundant shear and recrystallization. The crystallographic texture results indicated that the major texture components in the aluminum matrix were Brass {011}, S {123}, Goss {011} and Rotated Goss {011}. Moreover, it was concluded that Goss {011} and Rotated Goss {011} components appeared for high number of ARB cycles due to the adiabatic heat during ARB processing. The tensile strength of Al/Brass composite reached 330 MPa, which was 4.23 times and 1.83 times higher than those of annealed aluminum and monolithic aluminum, respectively. Finally, fracture surfaces of samples were studied, using field emission scanning electron microscope (FESEM), to reveal the failure mechanism.

Product miniaturisation and functional integration are currently global trends to save weight, space, materials and costs. This leads to an increasing demand for metallic micro components. Thus, the development of appropriate production technologies is in the focus of current research activities. Due to its efficiency, accuracy and short cycle times, microforming at room temperature offers the potential to meet the steadily increasing demand. During microforming, size effects occur which negatively affect the part quality, process stability, tool life and handling. Within this contribution, a multi-stage bulk microforming process from sheet metal is investigated for the materials Cu-OFE and AA6014 with regard to the basic feasibility and the occurrence of size effects. The results reveal that the process chain is basically suitable to produce metallic micro parts with a high repeatability. Size effects are identified during the process. Since several studies postulate that size effects can be minimised by scaling down the metallic grain structure, the grain size of the aluminium material AA6014-W is scaled down to less than one micrometre by using an accumulative roll bonding process (ARB). Subsequently, the effects of the ultrafine grain (UFG) structure on the forming process are analysed. It could be shown that a strengthened material state increases the material utilization. Furthermore, too soft materials can cause damage on the part during ejection. The occurring size effects cannot be eliminated by reducing the grain size.

The current study adopted a quantitative approach to investigating the mechanical properties, and their relationship to the microstructural features, of precipitation-strengthened 6061 aluminum alloy processed through accumulative roll bonding (ARB) and aging heat treatment. To serve this purpose, the contributions of different strengthening mechanisms including grain refinement, precipitation, dislocation and solid-solution strengthening to the yield strength of five-cycle ARB samples processed under pre-aged (ARBed) and aged (ARBed+Aged) conditions were examined and compared. Microstructural characterizations were performed on the samples through the transmission electron microscope (TEM) and X-ray diffraction (XRD). Also, the mechanical properties of the samples were investigated through the tensile test. The obtained results showed that an equiaxed ultrafine grain structure with nano-sized precipitates was created in the both ARBed and ARBed+Aged samples. The grain refinement was the predominant strengthening mechanism which was estimated to contribute 151 and 226 MPa to the ARBed and ARBed+Aged samples, respectively, while the dislocation and Orowan strengthening mechanisms were ranked second with regard to their contributions to the ARBed and ARBed+Aged samples, respectively. The overall yield strength, calculated through the root mean square summation method, was found to be in good agreement with the experimentally determined yield strength. It was also found that the presence of non-shearable precipitates, which interfered with the movement of the dislocations, would be effective for the simultaneous improvement of the strength and ductility of the ARBed+Agedsample .

Accumulative roll bonding (ARB) imposes severe plastic strain on materials without changing the specimen dimensions. ARB process is mostly appropriate for practical applications because it can be performed readily by the conventional rolling process. An Al-2wt%Cu alloy was subjected to ARB process up to a strain of 4.8. Stacking of materials and conventional roll-bonding are repeated in the process. In this study, corrosion behavior of an Al-2wt%Cu alloy fabricated by ARB process was studied in 3.5%wtNaCl solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The morphology of structures was analyzed by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). Also, the electrochemical experiments showed that corrosion resistance of samples decreases with increasing the number of ARB cycles due to the formation of oxide layer on defects and energetic regions such as grain boundaries with low/high angle and high density dislocations accumulated in sub-grains. According to the nyquist curves, by continuing the process, the diameters of semicircles decreased and the corrosion resistance and the polarization resistance subsequently decreased. After 6-cycle ARB, link up of small pits and micro crack were seen. Also, with increasing the number of the ARB cycles, the mean grain size of specimens decreased and it reached to 650 nm after 6 cycles of ARB process.

In this study, the Al/Al2O3-SiC hybrid composite was produced by accumulative roll bonding (ARB). In the first and the second cycles, the particles were uniformly poured between the Al strips during each ARB cycle. In the subsequent cycles, ARB was repeated up to six cycles without adding the particles between the layers. After the total eight cycles, the particles were distributed uniformly without agglomeration in the Al matrix. The corrosion behavior of the hybrid composite was investigated and compared with that of the annealed and ARB processed Al. The corrosion tests were conducted by the potentiodynamic and electrochemical impedance spectroscopy tests in 3.5 wt-% NaCl solution. The anodic potential of the pure Al processed by ARB was more positive than that of the annealed Al while its corrosion current density was higher. The corrosion potential of the hybrid composite was somewhere between the annealed Al and ARB processed Al. The hybrid composite exhibited the lowest current density and the highest charge transfer resistance. The increased corrosion resistance of the hybrid composite was attributed to the inert character of the Al2O3 and SiC particles because these particles could decrease the active sites of the material surface and impeding the corrosive attacks.

In this article, for the first time, the forming limit diagram (FLD) and mechanical properties of aluminum foil samples processed by the accumulative roll bonding (ARB) process have been studied experimentally. For this purpose, thin aluminum foils with a thickness of 200 microns have been produced using ARB in five passes at ambient temperature. By rising the number of ARB passes, the ultimate tensile strength (UTS) enhanced drastically, and at the end pass of ARB, it reached 393 MPa, about 5.9 times larger than the initial sample. Also, during the ARB process, the applied strain increased, and the thickness of the layers decreased, and the bonding quality between layers improved. SEM images of tensile fracture surface after five cycles showed the mechanism of fracture retained ductile. However, due to the unevenly applied strain, the dimples were drawn in different directions, and their depth and number were reduced relative to the raw material. The area under the FLDs, a criterion of formability, declined sharply after the first pass and then increased at a low rate until the final pass. The trend of similar changes of formability in the tensile (elongation) and Nakazima tests (FLDs) was reported. Responsibility for all mechanical properties and ductility changes is related to the ARB process’s nature and the two dominant mechanisms of strain hardening and grain refinement.

Austenitic stainless steels X4CrNi18-12 and X8CrMnNi19-6-3 were processed by accumulative roll bonding (ARB). Both materials show an extremely high yield strength of 1.25 GPa accompanied by a satisfactory elongation to failure of up to 14% and a positive strain rate sensitivity after two ARB cycles. The strain-hardening rate of the austenitic steels reveals a stabilization of the stress-strain behavior during tensile testing. Especially for X8CrMnNi19-6-3, which has an elevated manganese content of 6.7 wt.%, necking is prevented up to comparatively high plastic strains. Microstructural investigations showed that the microstructure is separated into ultrafine-grained channel like areas and relatively larger grains where pronounced nano-twinning and martensite formation is observed.

In this study, Al/Steel multilayer composite was produced by accumulative roll bonding (ARB) process using Al-1100 and St-12 strips. Microstructure, mechanical properties and corrosion behavior of the composite were studied by scanning electron microscopy (SEM), tensile test, Vickers microhardness tests, cyclic polarization and electrochemical impedance spectroscopy (EIS) measurement in 3.5 wt% NaCl solution. After one ARB cycle (2 roll-bonding cycles), the multilayer composite of 4 layers of Al and 2 layers of steel was produced. The tensile strength of the Al/steel multilayer composite reached 390.57 MPa after the first ARB cycle, which was 1.29 times larger than that of the starting steel while composite density was almost half the density of the steel. Corrosion behavior of the composite revealed a considerable improvement in the main electrochemical parameters, as a result of enhancing influence of cold rolling. The results indicated that strength and corrosion resistance of Al/steel composite generally decreases and elongation increases after annealing.

The ultrafine grain structure is very difficult to fabricate by severe plastic deformation (SPD) for metals with poor formability. In this paper, a fabrication technology of ultrafine structured dissimilar laminated metal composite sheets (LMCS) was developed for poor plastic metals which have low elongation by hot accumulative roll bonding (ARB) in conjunction with cold rolling. The hot ARBed 1100/7075 LMCS was cold rolled at room temperature after recrystallization annealing treatment. An ultrafine structured dissimilar LMCS was obtained without undergoing severe cold rolled deformation. The mechanical properties were enhanced and optimized by using heat treatment technology. The accelerated refining mechanism of grain was revealed by microstructure characterization of the composite sheet. The enhanced strength was mainly derived from the fine layers, refined grains, increased dislocation accumulation, and abundant dispersoids. The results of the research are helpful in improving the mechanical properties of dissimilar LMCS and optimizing the preparation technology.

The effect of pre-existing nano sized precipitates on the mechanisms and rate of grain refinement has been investigated during the severe plastic deformation. A binary Al–0.2Sc alloy, containing coherent Al3Sc particles, of 3.62 nm in diameter has been deformed by accumulative roll bonding up to 10 cycles. The resulting deformed structures were quantitatively analyzed using electron backscattered diffraction and transmission electron microscope techniques, and the results have been compared to those obtained from a solution treated Al–0.2Sc alloy, deformed up to same accumulative roll bonding cycles. The fraction of high-angle grain boundaries and grain size in all materials was increased and decreased gradually with increasing equivalent strain, respectively. However, the Aged-ARB alloy had relatively higher fraction of high-angle grain boundaries and smaller grain size than those of ST-ARB specimens at the same accumulative roll bonding cycles. It was found in an Al-0.2%Sc alloy that starting microstructures significantly affect the formation of ultrafine grains during severe plastic deformation. It was shown that the small Al3Sc precipitates are more effective on microstructural evolution during accumulative roll bonding process. Existence of fine precipitates in the starting material greatly accelerated the microstructure refinement. In this regards some unique phenomena, including softening during severe plastic deformation and dissolution of pre-existing Al3Sc, were observed.

The formation of alloys by particle reinforcement during accumulative roll bonding (ARB), and subsequent annealing, is introduced on the basis of the binary alloy system Al-Cu, where strength and electrical conductivity are examined in different microstructural states. An ultimate tensile strength (UTS) of 430 MPa for Al with 1.4 vol.% Cu was reached after three ARB cycles, which almost equals UTS of the commercially available Al-Cu alloy AA2017A with a similar copper content. Regarding electrical conductivity, the UFG structure had no significant influence. Alloying of aluminum with copper leads to a linear decrease in conductivity of 0.78 µΩ∙cm/at.% following the Nordheim rule. On the copper-rich side, alloying with aluminum leads to a slight strengthening, but drastically reduces conductivity. A linear decrease of electrical conductivity of 1.19 µΩ∙cm/at.% was obtained.

In this study, a kind of Al-TiB2/TiC in situ composite was successfully prepared using the melt reaction method and the accumulative roll-bonding (ARB) technique. The microstructure evolution of the composites with different deformation treatments was characterized using field emission scanning electron microscopy (FESEM) and a transmission electron microscope (TEM). The mechanical properties of the Al-TiB2/TiC in situ composite were also studied with tensile and microhardness tests. It was found that the distribution of reinforcement particles becomes more homogenous with an increasing ARB cycle. Meanwhile, the mechanical properties showed great improvement during the ARB process. The ultimate tensile strength (UTS) and microhardness of the composites were increased to 173.1 MPa and 63.3 Hv after two ARB cycles, respectively. Furthermore, the strengthening mechanism of the composite was analyzed based on its fracture morphologies.