Accumulative Roll Bonding Process Research Articles

Grain refinement and mechanical properties of CP-Ti processed by warm accumulative roll bonding

Accumulative roll bonding (ARB), a severe plastic deformation technique, was used in this study to process commercially pure titanium (CP-Ti) at 450°C. Sheet samples were processed by seven consecutive ARB cycles, with an overall equivalent strain of 5.6. Mechanical characterization and microstructural examination were carried out on the processed material to track their changes and relationships with regard to one another. Electron microscopy, TEM in particular, revealed significant grain refinement in the material, with submicron microstructure achieved even after one cycle of warm processing. Further processing was shown to progressively fragment the highly elongated grains, ultimately producing a predominantly-equiaxed ultrafine grain structure with an average grain size of ∼100nm. Tensile strength and microhardness of the material increased with the number of ARB cycles; the strength–grain size relationship followed the Hall–Petch equation. The overall grain refinement and strengthening levels observed here are close to those reported in the literature for ARB processing of CP-Ti at ambient temperatures. This demonstrates the ability of warm ARB can be as effective as cold ARB, while offering several advantages for industrial utilization.

Study on the microstructure and mechanical properties of multilayer Cu/Ni composite processed by accumulative roll bonding

In the present research, Cu/Ni multilayer composite was produced by accumulative roll bonding (ARB) process. The microstructure evolution and mechanical properties of the multilayered Cu/Ni composites were evaluated within different cycles of ARB process. It was observed that as the number of ARB cycles increased, the thickness of Ni layers was decreased and synchronous necking and fracturing occurred. After six ARB cycles, a multilayer Cu/Ni composite with homogeneously distributed fragmented nickel layers in Cu matrix was achieved. It was found that with increasing strain during ARB cycles strength and elongation of these composites increased. The observations of fracture surfaces after tensile tests revealed that rupture mode of Cu/Ni multilayer composites is ductile rupture with shear dimples.

Texture evolution during ARB (Accumulative Roll Bonding) processing of Ti–10Zr–5Nb–5Ta alloy

Titanium alloys are extensively used in a variety of applications due to their good mechanical properties, high biocompatibility and corrosion resistance. In the last decade, α-type Ti alloys containing Zr, Nb and Ta have received much attention, because they exhibit not only high strength but also bio-corrosion resistance and high biocompatibility. A α-type Ti–10Zr–5Nb–5Ta alloy was processed by Severe Plastic Deformation (SPD) – Accumulative Roll Bonding (ARB) procedure and investigated with the aim to observe the texture development during ARB processing. Texture data for the (0002), (101¯0), (101¯1) and (101¯2) Pole figures (PFs) were obtained by X-ray experiments and Inverse Pole Figures (IPFs) and Orientation Distribution Functions (ODFs) were determined. The results showed presence of {022¯3}〈101¯0〉 and {011¯1}〈101¯0〉 texture components, {0001} basal fibre and {011¯0}, {112¯0}, {112¯3}, {112¯6} fibres.

Ultrafine grained AA1050/AA6061 composite produced by accumulative roll bonding

In this work accumulative roll bonding (ARB) was used to combine AA1050 and AA6061 sheets to produce an AA1050/AA6061 composite sheet with ultrafine grained (UFG) structure. Two different starting materials were roll bonded as alternate layers up to 5 rolling cycles with 200°C pre-heating for 3min before each cycle. Other two types of the UFG sheets with monotonic starting materials, AA1050/AA1050 and AA6061/AA6061, were fabricated by the same ARB process for comparison. The AA1050/AA6061 composite sheets with strong bonding between different materials were obtained and substantial grain refinement was achieved after ARB processing. It was found that two different materials in the AA1050/AA6061 composite deformed in a nearly identical way during the first 3 ARB cycles. Afterwards the AA6061 started to neck and eventually fractured. The areas around the interface of two different materials were observed by transmission electron microscopy (TEM) and it was found that the microstructure of the bonded interface was quite complex. Two types of interfacial morphologies were observed along the AA1050/AA6061 interfaces: Type I is the area with direct contact of fresh metals and type II is the area with original metals with surface brittle layers in between. The rule of mixture has been applied to predict the strength of the AA1050/AA6061 composite sheet using the mechanical properties of the AA1050/AA1050 and AA6061/AA6061 sheets. The predicted and the measured tensile strength values are comparable to each other. The hardness values of the AA1050 and AA6061 layers in the composite are close to those measured in the monotonic material laminates, which indicated that both materials accumulated similar strain no matter if they are deformed in the composite sheets or in the single material sheets.

Fabrication of Al/Al3Mg2 composite by vacuum annealing and accumulative roll-bonding process

Al3Mg2 produced by the reaction between 1060-Al plates and AZ31-Mg foil was introduced homogeneously in the 1060-Al matrix during an accumulative roll-bonding (ARB) process. A type of aluminum metal matrix composite (AMMC) called intermetallic compound-reinforced AMMC was manufactured. Investigations regarding the hardness and tensile properties of the composites showed that the Vickers microhardness, tensile strength, and elongation of the Al/Al3Mg2 composites increased with the number of ARB cycles. Compared with the annealed and ARB monolithic 1060-Al, the Al/Al3Mg2 composites showed excellent mechanical properties and low density after the sixth ARB cycle.

Fabrication of Al/Ni/Cu composite by accumulative roll bonding and electroplating processes and investigation of its microstructure and mechanical properties

Al–Ni–Cu composite was produced using accumulative roll bonding (ARB) and electroplating processes. Nickel was electroplated on copper substrate for a certain time and voltage. In this study, the microstructural evolution and mechanical properties of the Al–Ni–Cu composite during various ARB cycles were studied by optical and scanning electron microscopes, microhardness, tensile and bending tests. It was observed that at first, nickel layers and then copper layers, were necked, fractured and distributed in aluminum matrix as accumulative roll bonding cycles were increased. Finally, after 11 cycles of ARB process, a completely uniform composite was produced with a homogeneous distribution of copper and nickel particles in aluminum matrix. The results showed that by increasing the number of ARB cycles, the bending strength of produced composite was increased. Also, it was found that when the number of cycles was increased, not only elongation was increased but also the tensile strength of the composite was improved. Microhardness for different elements in different cycles was also evaluated. Finally, fracture surfaces of samples were studied, using scanning electron microscopy (SEM), to reveal the failure mechanism.

Fabrication of Al/Cup composite by accumulative roll bonding process and investigation of mechanical properties

In the present work, accumulative roll bonding (ARB) process was used to produce Al/Cup composite using Al 1100 strips and Cu fine particles. Microstructure and mechanical properties of the composites were studied during various ARB cycles by scanning electron microscopy (SEM), tensile test and the Vickers micro-hardness test. The SEM results revealed that, as the ARB cycle increases the layer of Cu particles is broken which leads to generation of elongated dense Cu clusters. At higher strains, the size of elongated clusters reduces while their uniformity and sphericity increase. This microstructure changes leads to improving the hardness, strength and elongation during ARB process. Generally, the mechanical properties of Al/Cup composite are better than those of pure Al at the same cycle of ARB. The results also demonstrated that, the Cu reinforcement particles in the form of uniformly dispersed clusters improve simultaneously the strength and toughness of Al during the ARB process.

Microstructural Evolution with Annealing of Ultralow Carbon IF Steel Severely Deformed by Six-Layer Stack ARB Process

A sample of ultra low carbon IF steel was processed by six-layer stack accumulative roll-bonding (ARB) and annealed. The ARB was conducted at ambient temperature after deforming the as-received material to a thickness of 0.5 mm by 50% cold rolling. The ARB was performed for a six-layer stacked, i.e. a 3 mm thick sheet, up to 3 cycles (an equivalent strain of ~7.0). In each ARB cycle, the stacked sheets were, first, deformed to 1.5 mm thickness by 50% rolling and then reduced to 0.5 mm thickness, as the starting thickness, by multi-pass rolling without lubrication. The specimen after 3 cycles was then annealed for 0.5 h at various temperatures ranging from 673 to 973 K. The microstructural evolution with the annealing temperature for the 3-cycle ARB processed IF steel was investigated in detail by transmission electron microscopy observation. The ARB processed IF steel exhibited mainly a dislocation cell lamella structure with relatively high dislocation density in which the subgrains were partially observed. The selected area diffraction (SAD) patterns suggested that the misorientation between neighboring cells or subgrains was very small. The thickness of the grains increased in a gradual way up to 873 K, but above 898 K it increased drastically. As a result, the grains came to have an equiaxed morphology at 898 K, in which the width and the thickness of the grains were almost identical. The grain growth occurred actively at temperatures above 923 K.

Evaluation of mechanical properties of 1060-Al reinforced with WC particles via warm accumulative roll bonding process

In the present study, aluminum metal matrix composites (AMMCs) reinforced with tungsten carbide (WC) particles are manufactured through warm accumulative roll bonding (ARB). The composite microstructure shows excellent WC particle distribution in the Al matrices, and no reaction between Al and WC is observed. Compared with the ARBed 1060-Al, the Al/WC composites show a higher number of dislocations, as suggested by the introduction of WC particles. The tensile, hardness, and wear properties of the Al/WC composites are determined. The introduction of 3vol% WC particles to the Al matrix via the warm ARB process leads to significantly enhanced mechanical properties.

Effect of warm accumulative roll bonding on the evolution of microstructure, texture and creep properties in the 7075 aluminium alloy

The commercial 7075 Al alloy was severely deformed at 300°C by a 3:1 thickness reduction per pass accumulative roll bonding (ARB) process up to 5 passes. Examinations by transmission electron microscopy and electron backscatter diffraction revealed that the alloy microstructure was finer and more misoriented with increasing the number of ARB passes. The 5-passes sample exhibited a mean cell/(sub)grain diameter of 355nm and a mean boundary misorientation angle of 33°. The texture of the processed alloy was characterized by a β-fibre, whose intensity increased with increasing the number of ARB passes. This intensification process is enhanced by the cutting and stacking steps promoting the formation of the Dillamore orientation. Uniaxial tensile tests conducted at 300°C and at an initial strain rate of 10−2s−1 revealed that the processed alloy exhibited superplasticity, which was very sensitive to the stability of its microstructure at the testing temperature. An elongation to failure of 202% was registered for the 4-passes sample. Therefore, the present ARB process would allow short forming times at much lower temperatures than conventional.

Structural evaluation and mechanical properties of nanostructured Al/B4C composite fabricated by ARB process

Nanostructured Al/B4C composites with an average grain size of 151nm were successfully fabricated in the form of sheets, by using accumulative roll bonding (ARB) process. Furthermore, monolithic Al (without B4C particles) also was processed by the same method for comparison. The microstructure of the composites, evaluated by optical and scanning electron microscopy, revealed the properly distributed B4C particles in the Al matrix. The grain size of the Al matrix, after the final ARB cycle, is studied using Williamson–Hall analysis of X-ray diffraction (XRD) pattern of the deformed sample. Mechanical properties of the specimens were investigated by tensile and hardness tests. The tensile strength and microhardness of the processed samples increased with increasing the number of ARB cycle. Whereas, the elongation dropped abruptly at the first cycle; afterwards, it remained nearly constant in the monolithic samples and increased slightly in the composites.

Variant selection of martensite transformation from ultrafine-grained austenite in Fe–Ni–C alloy

Abstract Variant selection rule of martensite transformed from ultrafine-grained austenite was investigated. The specimens were fabricated by severe plastic deformation using accumulative roll bonding (ARB) process with different ARB cycles. The results proved that interaction energy between residual stress in austenite and shape deformation accompanying martensitic transformation determined the variant selection of martensite transformed from the 1-cycle ARB processed specimen having coarse-grained deformed austenite. In contrast, austenite grain shape essentially determined the preferred variants of martensite transformed from the elongated ultrafine-grained austenite fabricated by the 6-cycle ARB process.

Nanoindentation Creep Behavior of Nanocomposite Sn-Ag-Cu Solders

High-density, ultrasmall-pitch electronic applications require miniaturized solder bumps with improved thermomechanical performance. In addition, novel techniques which are able to precisely characterize these solder bumps are needed. One approach to meeting both of these requirements is to make use of recently developed nanocomposite solders with enhanced creep resistance, and to characterize these solders using a nanoindentation technique. In the present study, the creep behavior of ceria-reinforced nanocomposite solder foils fabricated by the accumulative roll-bonding process was characterized using a depth-sensing nanoindentation technique. It was found that the creep resistance of the composites increased with increasing volume fraction of CeO2 reinforcement, and it was deduced that the creep deformation of this nanocomposite proceeded by deformation of the matrix, with the role of the reinforcement being to increase the creep resistance by reducing the effective stress acting on the matrix. The values of the creep exponent suggested that the dominant creep deformation mechanisms involved were diffusion creep and grain boundary sliding.

Effect of W particles on the properties of accumulatively roll-bonded Al/W composites

In the present study, aluminum metal matrix composites reinforced with pure tungsten particulates are manufactured through warm accumulative roll bonding (ARB). X-ray diffraction analysis reveals no Al–W intermetallics in the composites. The microstructure of the composites shows excellent W particle distribution in the matrixes. Tensile, hardness, and electrical conductance properties of the composites are determined. The results show that the introduction of 4.2 vol% W particles to Al matrix via ARB process leads to significantly enhanced mechanical properties and excellent electrical conductivity.

Development of Cube Texture in Pure Ni Following Ultrahigh Straining by Accumulative Roll Bonding and Annealing

The evolution of cube texture has been investigated in pure Ni (~99.97%) following ultra high straining by Accumulative Roll Bonding (ARB) and annealing. Fully annealed sheets of pure Ni with average recrystallized grain size of ~28 (henceforth termed as fine grained starting material) and 650 µm (henceforth termed as coarse grained starting material) were used as the starting material for the ARB processing. ~50% reduction was imparted in each cycle of ARB and the process was carried up to 8 cycles resulting in an accumulated equivalent strain (εeq) of 6.4. The deformed materials were subsequently annealed at temperatures ranging between 300 to 800°C for one hour. In addition few samples were annealed at 300°C for different time intervals to observe the evolution of texture components. In all cases textures were carefully characterized using Electron Back Scatter Diffraction (EBSD) technique.

Development of texture during ARB in metal matrix composite

In the present study, the accumulative roll bonding (ARB) process was used as a technique for manufacturing aluminium–alumina composites. Textural evolution during the ARB process of composites was evaluated using X-ray diffraction. After the first ARB cycle, copper {112}〈111〉 and brass {011}〈211〉 were the major texture components. However, with the progress of deformation after 5 cycles, the components transformed completely, and the rotated cube {001}〈110〉 component became dominant, which remained as the major component in higher cycles (ninth and thirteenth). This shear texture was developed due to the shear deformation induced by the high level of friction between the rolls and the strips. Generally, the intensity of all the texture components, except that of the rotated cube, was very weak. This result is attributed to the presence of second phase particles.

Microstructure and mechanical properties of the Mg/Al multilayer fabricated by accumulative roll bonding (ARB) at ambient temperature

sAbstract The Mg/Al laminated composites were fabricated by the accumulative roll bonding (ARB) at ambient temperature using the pure magnesium and commercial pure Al sheets. Mg grains were refined after the primary sandwich preparation and then homogenized during the following ARB process while the grain size of Al layer decreased with increasing of the accumulated strains. Both the yield strength and ultimate strength along rolling direction and transverse direction increased gradually while the elongation to failure along both directions decreased with increasing of the ARB cycles. Formation of the Mg 17 Al 12 phase indicated that the ARB process at ambient temperature could lead to a metallurgic bonding of the Mg/Al interface.

Fabrication of High-Strength Al/SiC p Nanocomposite Sheets by Accumulative Roll Bonding

Accumulative roll bonding (ARB) was successfully used as a severe plastic deformation method to produce Al-SiC nanocomposite sheets. The effects of process pass and amount of SiC content on microstructure and mechanical properties of the composites are investigated. As expected, production of ultrafine grain structures by the ARB process as well as nanosize particulate reinforcements in the metal matrix composite (MMC) resulted in excellent mechanical properties. According to the results of the tensile tests, it is shown that the yield and tensile strengths of the composite sheet increased with the number of ARB cycles without saturation at the last cycles. Scanning electron microscopy (SEM) revealed that the particles had a random and uniform distribution in the matrix by the last ARB cycles, and strong mechanical bonding takes place at the interface of the particle matrix. Transmission electron microscopy (TEM) and the corresponding selected area diffraction (SAD) demonstrate ultrafine grains with large misorientation in the structure. It is also shown that by increasing the volume fraction of particles up to 3.5 vol pct, the yield and tensile strengths of the composite sheets increased more than 1.3 and 1.4 times the accumulative roll-bonded aluminum sheets, respectively.

Pitting corrosion susceptibility of ultrafine grains commercially pure aluminium produced by accumulative roll bonding process

Ultrafine grains (UFGs) of commercial pure (CP) aluminium were produced by accumulative roll bonding (ARB) process. The relative pitting corrosion susceptibility of a coarse grained (CG) initial sample and ARB processed samples was investigated using direct current electrochemical techniques and immersion test. Applying the ARB process for eight passes was found to significantly decrease the anodic breakdown and repassivation potentials (Ebd and Erp respectively) of the samples. It is also postulated that the protective characteristics of passive film were diminished through the ARB process. These results were interpreted in terms of the high defects and inhomogeneities in oxide film as well as cathodic intermetallic particles (Al3Fe and Al6Fe intrinsic inclusions). SEM observations from the sample surfaces after the immersion test confirmed these results.

Growth of intermetallic phases in Al/Cu composites at various annealing temperatures during the ARB process

The purpose of this study is to discuss the effect of annealing temperatures on growth of intermetallic phases in Al/Cu composites during the accumulative roll bonding (ARB) process. Pure Al (AA1100) and pure Cu (C11000) were stacked into layered structures at 8 cycles as annealed at 300 °C and 400 °C using the ARB technique. Microstructural results indicate that the necking of layered structures occur after 300 °C annealing. Intermetallic phases grow and form a smashed morphology of Al and Cu when annealed at 400 °C. From the XRD and EDS analysis results, the intermetallic phases of Al2Cu (θ) and Al4Cu9 (γ2) formed over 6 cycles and the AlCu (η2) precipitated at 8 cycles after 300 °C annealing. Three phases (Al2Cu (θ), Al4Cu9 (γ2), and AlCu (η2)) were formed over 2 cycles after 400 °C annealing.