Accumulative Roll Research Articles

Nanostructuring of Ferritic Steel: A Review on Enhanced Surface Properties Using Ultrasonic Shot Peening

Nanostructuring of ferritic stainless steel refers to the process of intentionally reducing the grain size of the material at the nanoscale level. By manipulating the microstructure of the steel, it is possible to enhance its mechanical, physical, and chemical properties. Nanostructuring can significantly improve the strength, hardness, and wear resistance of ferritic stainless steel, while still maintaining its corrosion resistance. The increased density of grain boundaries and the complex dislocation network within the nanostructured material contribute to these improved properties. Moreover, the nanostructured ferritic stainless steel exhibits enhanced thermal stability, leading to better high-temperature performance and resistance to creep deformation. The small grain size also allows for increased precipitation of secondary phases, such as carbides, nitrides, or intermetallic compounds, which can further improve the material's properties. There are several methods to achieve nanostructuring in ferritic stainless steel, such as severe plastic deformation (SPD) techniques like high-pressure torsion, equal channel angular pressing, and accumulative roll bonding. These techniques impose extreme plastic deformation on the material. Leading to grain refinement below the micrometre range. Also, a novel method of surface nanostructuring ultrasonic shot peening (USP) is discussed in detail. Shot peening is a process in which small, spherical media, typically made of steel or ceramic, called "shots," are propelled onto the surface of a material at high velocities. Ultrasonic shot peening enhances the traditional shot peening process by introducing high-frequency vibrations to the shots. These vibrations are generated by an ultrasonic transducer, which is immersed in a bath of shots and liquid. The vibrations are transmitted through the liquid to the shots, causing them to collide with the surface of the ferritic steel at even higher velocities and energy levels than in traditional shot peening. In summary, nanostructuring of ferritic stainless steel offers great potential for tailoring the material's properties to meet specific application requirements, including improved strength, hardness, wear resistance, corrosion resistance, and high-temperature performance. USP is an effective surface treatment method for ferritic steel, offering advantages in terms of fatigue life, stress corrosion cracking resistance, surface hardness, and wear resistance.

Effect of accumulative hot rolling on the microstructure and mechanical properties of dual-phase titanium alloy consolidated via SPS sintering

The improvement of microstructure and mechanical properties of Ti alloys is of great significance for their industrial application. In this study, a developed multi-step hot deformation process was employed to regulate the grain boundaries (GBs), hetero-phase boundaries (PBs) and dislocation structure for dual-phase titanium alloy. The effects of accumulative thermal deformation ratios from 33% to 75% (2–8 cycles) on the microstructure and mechanical properties have been investigated. It is found that the sintered sample shows a typical Widmanstätten structure without obvious pores and micro-cracks. However, with the increase of the deformation ratio, for the hexagonal close packed (HCP) Ti, the crystal orientations of {011‾0} and {1‾21‾0} were gradually transformed into {0001}, with the change of high-angle grain boundaries (HAGBs) to low-angle grain boundaries (LAGBs). The density of stored geometrically necessary dislocations (GNDs) density raised dramatically from 1.95 × 1014 m−2 to 6.5 × 1014 m−2, and various types of dislocations have been characterized. For the β phase, in the thermal deformation process, high density α-precipitates with an average thickness below 20 nm had formed with Burgers relationship of {110}BCC//{0001}HCP and <1‾11 >BCC//<21‾1‾0 >HCP. Finally, the yield strength of the dual-phase titanium alloy increased dramatically from 881 MPa to 1178 MPa, and the ductility can still maintain at above 8.5%. The enhanced strength was mainly contributed by the increase of geometrically necessary boundaries (GNBs) and nano-lamellae boundaries (NLBs). Therefore, this strategy of combining hetero-phase boundaries (PBs) and dislocation engineering could open up new avenues to designing strong and ductile titanium matrix materials.

Role of interfaces on the mechanical response of accumulative roll bonded nanometallic laminates investigated via dislocation dynamics simulations

Unraveling the effects of continuous dislocation interactions with interfaces, particularly at the nanometer length scales, is key to a broader understanding of plasticity, to material design and to material certification. To this end, this work proposes a novel discrete dislocation dynamics-based model for dislocation interface interactions tracking the fate of residual dislocation on interfaces. This new approach is used to predict the impact of dislocation/interface reactions on the overall mechanical behavior of accumulative roll bonded nanometallic laminates. The framework considers the dynamic evolution of the interface concurrent with a large network of dislocations, thus, accounting for the local short and long range effects of the dislocations under the external boundary conditions. Specifically, this study focuses on two-phase Fe/Cu nanometallic laminates, and investigates the role of the underlying elastic and plastic contrast of the Fe and the Cu layers on the composite response of the material. Moreover, the role of initial microstructures, resulting from processing is also investigated. Subsequently, the model is used to examine the effect of layer thickness and interface orientation relationship on the residual stresses of the relaxed microstructure. The associated mechanical response of these laminates are compared when loaded under normal direction compression, as well as shear compression. Finally, this work predicts a dominant effect of the layer thickness, as compared to the interface orientation relationship, on the macroscopic response and on the residual stresses of these nanolaminates, while the local dislocation transmission propensity through the interface is significantly influenced by the corresponding orientation relationship.

CORROSION, WEAR AND MECHANICAL PROPERTIES OF LAMINATED Al/TiC COMPOSITES

In the recent study, accumulative roll bonding (ARB) and powder metallurgy processes are used as a combined technique to fabricate AA1050/TiC composite strips. Then, corrosion, mechanical, wear properties and microstructural evolution of them have been investigated via TiC Wt.%. All composite samples were fabricated after four cycles to get a uniform scattering of particles inside the metallic matrix. Moreover, density as a physical property and electrical resistivity and conductivity have been investigated vs particles value. The results showed that by increasing the particles value (Wt.%), hardness, density, corrosion and wear resistance of samples improved while their electrical conductivity, bonding strength and elongation decreased. For samples with 10[Formula: see text]Wt.% of TiC and in comparison with the monolithic sample, the hardness and tensile strength of composite samples improved 127% and 63%, respectively. Finally, SEM morphology of worn and corrosive surfaces has been investigated.

Dual heterogeneous Cu–Al2O3/Cu laminated composite with high strength and ductility prepared by accumulative roll bonding

Cu–Al2O3/Cu laminated dual heterogeneous microstructure composites with alternating coarse/fine grain distributions were prepared using a combination of accumulative roll bonding and annealing processes. The average layer thickness of the Al2O3/Cu layers is 2.1 μm and that of the Cu layer is 4.2 μm, and meanwhile, the average grain size of the Al2O3/Cu layers and Cu layers are 0.25 μm, 2.3 μm respectively. The strength of Al2O3/Cu layer is higher than that of the Cu layer because of the additional dispersion strengthening and the stronger grain boundary strengthening. Owing to significant differences in the structural and mechanical properties of the layers in this material, geometrically necessary dislocations accumulated at the interface during the tensile process; this resulted in significant heterogeneous deformation-induced strengthening, which yielded a laminated composite with a tensile strength of 413 MPa, tensile ductility of 27%, and excellent overall performance. This work provides a new design strategy for the preparation of high-strength high-ductility materials.

Microstructure and Mechanical Properties of AA1050/AA6061 Laminated Composites Fabricated through Three-Cycle Accumulative Roll Bonding and Subsequent Cryorolling.

In this study, AA1050/AA6061 laminated composites were prepared by three-cycle accumulative roll bonding (ARB) and subsequent rolling. The effects of the rolling process on the microstructure evolution and mechanical properties of AA1050/AA6061 laminated composites were systematically investigated. The results indicate that the mechanical properties of the laminated composites can be effectively improved by cryorolling compared with room-temperature rolling. The microstructure analysis reveals that cryorolling can suppress the necking of the hard layer to obtain a flat lamellar structure. Moreover, the microstructure characterized by transmission electron microscopy shows that cryorolling can inhibit the dynamic recovery and significantly refine the grain size of the constituent layers. Meanwhile, the tensile fracture surface illustrates that AA1050/AA6061 laminated composites have the optimal interfacial bonding quality after cryorolling. Therefore, the laminated composites obtain excellent mechanical properties with the contribution of these factors.

Carbon Fiber Breakage Mechanism in Aluminum (Al)/Carbon Fibers (CFs) Composite Sheet during Accumulative Roll Bonding (ARB) Process

Carbon Fiber Breakage Mechanism in Aluminum (Al)/Carbon Fibers (CFs) Composite Sheet during Accumulative Roll Bonding (ARB) Process

Bonding characteristics of aluminium laminates and aluminium–graphite composites processed by roll bonding

Roll bonding is a solid-state welding process, employed to join similar and dissimilar metals. Roll bonding with secondary particles in-between and accumulating the roll bonded material multiple times is an alternative method for manufacturing high-strength composites. In the current work, commercially pure aluminium strips are roll bonded at room temperature to 400 °C. The percent reduction varied from 10% to 70%, with an increment of 10%. Moreover, the aluminium strips are roll bonded with graphite particles dispersed in between (Al–Gr–Al). The aim is to study the effect of graphite particles on bonding behaviour. The critical process parameters such as the effect of temperature and percentage reduction on the bond strength are determined. The lap shear test is used to evaluate the bond strength. It is observed that the dispersion of graphite particles in between aluminium significantly increased the threshold reduction required for bond establishment. The threshold reduction decreases for roll-bonding aluminium with increasing temperature. Furthermore, it is observed that the bond strength significantly increases with increasing processing temperature. However, roll bonding with the graphite particles dispersed in between reduced the bond strength, and the effect was significant with increasing temperature. The bond strength of both Al and the Al–Gr–Al composites increases by increasing the reduction percentage. The de-bonded sample surfaces are analyzed using a scanning electron microscope. It is worth mentioning that the experimental outcomes of the current study predict the roll bonding parameters for the successful fabrication of an Al/Gr composite by accumulative roll bonding.

Evolution of Through-Thickness Texture and Microstructure of an ARB-Processed Nb1-Zr Alloy

AbstractThis study investigates the effects of accumulative roll bonding processing on a commercial Nb1Zr alloy. The sheets were subjected to preheating, followed by five reduction cycles. Microstructural evolution was examined through metallography, revealing increasing homogenization of the morphology across the laminate thickness. Microhardness increased from 109 HV to 187 HV in the final laminate due to grain refinement. Electron back-scattered diffraction analysis showed removal of shear strain effects with each deformation step, highlighting microstructural heterogeneity and texture variation. The Goss texture was intensified at the surface during the third cycle, attributed to surface recrystallization. Low-angle grain boundaries were prevalent initially, shifting to a bimodal distribution favoring high-angle grain boundaries with increased deformation, linked to dynamic recovery and recrystallization.

New aspects of solid-state welding in the aluminium accumulative roll bonding

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.

Synergistic mechanism of strengthening and toughening of tissue regulation response to Mg/Al composite laminates by hard plate accumulative roll bonding

The significance of light alloy in realizing the national strategy of energy saving and emission reduction and promoting the upgrading of the manufacturing industry is self-evident. Mg/Al composite laminates combine the lightweight of magnesium alloy and the plasticity and corrosion resistance of aluminum alloy. Traditional accumulative roll bonding technology relies on the advantage of introducing large deformation. Although high strength is obtained, it is often accompanied by a large loss of ductility, and there is a problem that it is difficult to balance strength and ductility. To solve this problem and optimize the process conditions, a new hard-plate accumulative roll bonding process is proposed in this paper, which is used to prepare high-performance Mg/Al composite plates, and the influence of forming temperature on the microstructure and mechanical properties of Mg matrix is studied. The results show that when the forming temperature is 350 °C, the properties of composite laminates are the best, the tensile strength can reach 243 MPa, the elongation is 14.7 %, and there are a lot of tearing edges and dimples on the fracture surface. At the same time, complete recrystallization can be realized at this temperature, and the opening of non-base slip can coordinate deformation stress, promote the dislocation slip, and reduce the dislocation density, SEM images show that there are no defects such as delamination at the interface, and a firm metallurgical bonding is achieved. It provides a new approach to the forming and manufacturing of high-quality lightweight heterogeneous composite laminates.

Mechanical, microstructural, and textural evaluation of aluminum-MWCNT composites manufactured via accumulative roll bonding at ambient condition

In the present study, aluminum-matrix composites reinforced by multi-walled carbon nanotubes (MWCNTs) were manufactured using the accumulative roll bonding (ARB) process. In the first step, MWCNTs were dispersed between two pieces of Al sheets that were then stacked together and rolled. In the second step, the above procedure was repeated for up to 12 cycles without adding MWCNTs. The microstructure and fracture surface of the composites were studied during various ARB cycles using optical microscopy (OM) and scanning electron microscopy (SEM). Also, the mechanical properties of the composites were measured employing tensile and Vickers hardness tests. More uniform dispersion of MWCNTs was found in the microstructure of the aluminum matrix after 12 ARB cycles. With an increase in the number of ARB cycles, the hardness of the composites was enhanced. The results indicated that after 11 cycles, both the elongation and tensile strength improved and strong interfacial bonding formed between MWCNTs and the Al matrix. However, the development of micro-cracks in the composite resulted in a decrease in elongation and tensile strength at the final cycle. SEM investigations of fracture surfaces revealed that the fracture mode of the composites changed from ductile to brittle in the final ARB cycle, while that of monolithic aluminum remained ductile for all ARB cycles. Texture analysis, also confirmed a transition from the initial recrystallized (Cube and Goss) texture to the ideal rolling texture, mainly with Copper and Dillamore components.

Study of changes in the aging process, microstructure, and mechanical properties of AA2024–AA1050 nanocomposites created by the accumulative roll bonding process, with the addition of 0.005 vol.% of alumina nanoparticles

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.

Investigation of corrosion behavior of Al–TiO2 nanocomposite produced using air plasma spray and accumulative roll bonding method

This work is an attempt to study the Al–TiO2 nanocomposite properties applying accumulative roll bonding process. For this purpose, nano Titania powder was first coated on aluminum foil by air plasma spraying process. The nanocomposite was then fabricated in one, two, three, five, and seven cycles by ARB. To investigate the effect of ARB process cycles on an Al-5% wt. TiO2 nanocomposite, characterization tests including XRD, quantitative XRD analysis by MAUD software, FESEM, EDS, electrochemical impedance, and TAFEL polarization tests were performed on the samples. The results indicate that the crystallite size reduced from 156 to 31 nm and the dislocation density quadrupled in the composite. The results of XRD analysis showed an increase in the dislocation density in the composite when the number of cycles increases. The reduction of crystallite size and increase of the grain boundaries have caused a sudden increase in the dislocation density. As the ARB cycle increases, the local porosity decreases and the local cracks due to the separation of the titanium sprayed droplets disappear in the matrix phase, and the reinforcing phase has more diffusion in the matrix. With the increase of ARB cycles, the percentage of titanium and oxygen elements on the surface was decreasing, but they remained until the last cycle. Among the non-rolled and rolled samples in different cycles, ARBed samples after 1 cycle and 5 cycles had not only the lowest and highest corrosion current densities but also the highest and lowest total resistance (Rt), respectively. This indicates max corrosion resistance due to the decrease in defect and porosity resulting from plasma spray and min corrosion resistance as a result of formation of galvanic cell between Al-matrix and Ti-reinforcing particles, respectively.

Comparison of Mechanical Properties in Ultrafine Grained Commercial-Purity Aluminum (A1050) Processed by Accumulative Roll Bonding (ARB) and High-Pressure Sliding (HPS)

Comparison of Mechanical Properties in Ultrafine Grained Commercial-Purity Aluminum (A1050) Processed by Accumulative Roll Bonding (ARB) and High-Pressure Sliding (HPS)

Enhancing grain refinement and mechanical properties of AA1100/MgAZ31/AA1100 composites by using different roll bonding techniques

This paper examines the microstructure and mechanical properties of AA1100/Mg AZ31/AA1100 composites processed by conventional accumulative roll bonding (ARB) and cross accumulative roll bonding (CARB) methods. Based on the results, with an increase in deformation strain, Mg layers gradually lose their continuity in the form of localized necking and fragmentation. However, changing the strain path and pre-annealing the initial sheets could retard and homogenize the plastic instabilities. According to the results of electron back-scattering diffraction (EBSD), applying severe plastic deformation led to refined-grain structures with equiaxed grains. The finer grains were obtained in composites processed by the CARB method following the pre-annealing treatment. Employing this procedure also intensified the basal-type texture and circled its shape. The strong basal texture and grain refinement led to the highest Mg alloy and Al hardness values of 99 and 64 HV, respectively. Furthermore, changing the strain path and pre-annealing treatment increased the elongation by 46% in the seventh pass compared to ARBed samples. Also, this procedure increased the ultimate strength from 375 to 391 MPa and gave rise to yield strength from 164 to 176 MPa.

Effects of the Number of Layers and Thickness Ratio on the Impact Fracture Behavior of AA6061/AA7075 Laminated Metal Composites

The initial thickness ratio and number of layers of dissimilar metal components greatly influence the impact performance of laminated metal composites. In this paper, positive and lateral impact tests of 5-layer composite sheets with thickness ratios of 3:1, 1.35:1, and 1:2 and 80-layer composite sheets prepared by ARB (accumulative roll bonding) were conducted to study the influences of the thickness ratio and layer number on the impact fracture behavior of composite sheets. The results showed that the higher the proportion of AA7075, the higher the bending strength of the AA6061/AA7075 laminated composite sheet; compared with the 5-layer composite sheet, the side impact performance of the 80-layer composite sheet is obviously improved, and its side impact strength, energy absorbed in the crack initiation stage, and crack propagation stage are better than those of the 5-layer composite sheet. In addition, the toughening mechanism of the 80-layer composite sheet is mainly that the increase in the number of layers makes the cracks deflect more frequently. Under the rapid impact load, the impact energy absorbed by the sample increases with the increase in the number of layers.

Enhancing the electrochemical performance of Sn-Zn alloy anode foil for lithium-ion batteries through microstructure design via accumulative roll bonding technique

In this study, we introduce a novel method for designing microstructures of Sn-45Zn alloy foils utilizing the accumulative roll bonding (ARB) technique, which is one of severe plastic deformation techniques that have been used for refining the microstructures of bulk metals. The electrochemical properties of Sn-Zn foil anodes with various microstructures achieved through the ARB method followed by annealing are investigated in lithium-ion batteries. The degree and characteristics of microstructural damage during electrochemical cyclic tests are also examined in detail to provide insights into the microstructural parameters that critically influence the capacity and cyclic behavior of the Sn-Zn alloy foil anode. Our findings suggest that the ARB-processed Sn-Zn alloy foil, characterized by nearly ultrafine grains composed of Sn and Zn phases with the Zn phase forming a continuous network, exhibits superior battery capacity and cycle life compared to the sample processed using the conventional rolling method. This superiority can be attributed to its unique microstructure obtained through ARB, which reduces pore density, suppresses pore interlinkage, decreases charge transport resistance and nucleation overpotential, and enhances Li-ion diffusivity in the electrode.

Effect of cube texture on local softening of friction stir welded joints for nanostructured AA2024 processed by accumulative roll bonding

The current research provides an insight into the correlation between the crystallographic textures, microstructure, and hardness of friction stir welded joints in nanostructured AA2024 alloys processed through accumulative roll bonding (ARB). Utilizing varying rotational speeds (250, 500, 750, and 1000 rpm) at a constant traverse tool (150 mm/min) during friction stir welding (FSW), microstructural analyses reveal distinct grain structures and texture components in the nugget zone. The fully recrystallized Cube {001}⟨100⟩ texture-oriented grains appear at the rotational speed of 750 rpm. The hardness profiles of ARB-processed strips after FSW at different rotational speeds show local softening in the nugget zones. There might be a hypothesis concerning the dissolution of stable and metastable precipitates based on generated heat input, providing insights into the mechanisms influencing hardness variations. Notably, the examination of Cube {001}⟨100⟩ texture and its correlation with local softening adds a valuable dimension to the understanding of microstructural changes in FSW of nanostructured AA2024 alloys processed by accumulative roll bonding process.

Microstructure and Mechanical Properties of Copper/Graphene Composites Fabricated via Accumulative Roll Bonding and Heat Treatment without a Controlled Atmosphere

Copper and its alloys are structural materials used in industries and engineering applications due to their excellent thermal and electrical conductivity and chemical stability. Integrating graphene, known for its exceptional electrical conductivity, into the copper matrix is a promising strategy to enhance mechanical properties without sacrificing electrical conductivity. The Accumulative Roll Bonding (ARB) process can effectively and homogeneously introduce graphene into the metal matrix and is adaptable to an industrial scale. This study investigates the impact of varying graphene concentrations and two heat treatment protocols (without a controlled atmosphere) on the mechanical and electrical properties of ARBed copper/graphene composites. Optical microscopy revealed minimal voids and graphene clumps, and the energy dispersive spectroscopy analysis revealed the absence of copper oxide in some samples. The conductivity test showed little influence of the graphene content and stress relief heat treatment temperature on electrical conductivity (~86% of the International Annealed Copper Standard) within a limited number of ARB cycles. The tensile tests did not reveal a significant influence of the graphene content and stress relief heat treatment temperature on the ultimate tensile strength (220–420 MPa) and elongation (~2%).