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Accumulative roll bonding (ARB) is a repeated cladding process in which two or more sheets of material are joined together by rolling at temperatures below recrystallization. The present review is focused on ARB of high‐alloy steels, which, among other laminated metal composites (LMCs), deliver the highest mechanical properties. After a brief description of high‐strength steels, history, and state of the art of LMCs, the principal roll bonding mechanism is explained. Further, the methodology of ARB of steels and variable parameters (stacking, temperature, etc.) are discussed. Known examples of steel–steel laminates are summarized with respect to their rolling temperature and mechanical properties. Further, the main toughening mechanisms of steel‐based LMCs are listed. The most promising candidates of high‐alloy steel laminates are presented in more detail. The important deformation mechanisms of twinning‐ and transformation‐induced plasticity (TWIP and TRIP) high‐alloy steels are explained. Microstructural changes and layer bonding as well as mechanical properties and damage behavior of two‐ and four‐layered TRIP/TWIP steel laminates are illustrated, including some specific phenomena, such as deformation lenses. Finally, by summarizing the analyzed data on steel laminates, conclusions and outlook are formulated. [ABSTRACT FROM AUTHOR]

Laminated metal composites have become a key strategy for the design and manufacture of metal parts with multiple combinations of excellent properties. This paper utilizes the differences in mechanical properties and recrystallization behavior of component metals to prepare a novel 316 L/(316 L-2.5 wt%Gd)/316 L neutron shielding laminated metal composites (LMCs) through composite rolling and solution treatment processes. LMCs have an excellent combination of properties: high strength (tensile strength: 571.36 MPa), sufficient tensile ductility (fracture elongation: 60 %) and high neutron shielding properties (thermal neutron shielding rate: > 90 %). Specifically, compared to the non-composite 316 L-2.5 wt%Gd neutron shielding material, the strength of the hot-rolled LMCs has increased by 2.0 times, and the elongation at fracture has improved by 3.3 times. After solid solution treatment, the elongation of LMCs is further increased, which is 6 times higher than non-composite 316 L-2.5 wt%Gd neutron shielding materials. The specially designed soft-hard matched 316 L/(316 L-2.5 wt%Gd) heterogeneous interfaces achieved good metallurgical bonding, with significant differences in grain sizes and strains. The main reasons for the enhanced strength and plasticity of LMCs are the geometric constraints caused by the layered structure composed of ductile and brittle metallic components, as well as the back-stress strengthening and strain hardening induced by deformation incompatibility at the heterogeneous interface. • 316 L/(316 L-2.5 wt%Gd) heterogeneous interfaces with different grain sizes and obvious differences in strains were constructed. • Heterogeneous structure and interfacial constraints synergistically enhance the strength and plasticity of 316 L/(316 L-2.5 wt%Gd)/316 L laminated composites. • Provides a promising solution to the difficult problem of mutual constraints between neutron shielding properties and mechanical properties. [ABSTRACT FROM AUTHOR]

Abstract By rolling and diffusion bonding, multilayered Zr/Ti composites were fabricated using commercial pure titanium (CP-Ti) and zirconium (Zr702) sheet as raw materials. For the as-fabricated Zr/Ti laminated metal composites (LMCs), quenching at different temperatures were carried out to refine the microstructure. Microstructures of Zr/Ti LMCs before and after the quenching were characterized by scanning electron microscope and electron backscatter diffraction. Micro-hardness and compression tests were performed to reveal the effect of quenching temperature on the mechanical properties of the Zr/Ti LMCs. It indicates that certain part of the microstructure can be refined by phase transition during quenching. The volume fraction of the quenching-affected (refined) microstructure increase with the increase of quenching temperature. Micro-hardness tests show that the hardness is not uniform along the thickness of the Zr/Ti LMCs due to the heterogeneous chemical composition and microstructure. The compressive strength of the Zr/Ti LMCs increases with the increase of the quenching temperature, which is mainly attributed to the fact that more microstructures have been refined in higher temperature quenching. [ABSTRACT FROM AUTHOR]

In this study, the effect of layer structure on the mechanical behavior of Ti/Al laminated metal composites (LMCs) was explored, focusing on the occurrence of an additional strengthening mechanism introduced by heterogeneous microstructures between constituent layers. Experimental results showed that the change in layer structure parameters and rolling conditions had a significant effect on the microstructure of the Al layer, and the difference in shear strain scale near the interface led to the formation of a grain refinement zone (GRZ) with various microstructural characteristics during dynamic recrystallization. In addition, the recrystallized distribution and texture evolution (i.e., the increasing recrystallized fraction and the intensifying shear texture r-Cube {001} 〈110〉) revealed that the deformation storage energy as the driving force of recrystallization played an important role in the difference in the heterogeneous degree formed in various Ti/Al LMCs. On the other hand, the strength deviation between the experimental strength and the theoretical strength predicted by the rule of mixture can be detected in all LMCs with different thickness ratios after hot rolling, resulting from the pile-up of geometrically necessary dislocations (GNDs) caused by the synergetic deformation induced by mechanical incompatibility between Ti and Al layers during plastic deformation. With a change in the layer structure parameter, a considerable strength deviation in the Ti/Al LMC with a large thickness ratio indicated that the high mechanical incompatibility between the constituent layers was conducive to the enhancement of additional strengthening behavior. • Microstructural evolution and mechanical behavior of Ti/Al LMCs with various layer structures were explored. • The formation of grain refinement zone near the interface with various microstructural characteristics was analyzed • The contribution of interfacial effect introduced by mechanical incompatibility on properties were investigated. [ABSTRACT FROM AUTHOR]

The layer thickness has been reported to play a crucial role in laminated metal composites (LMCs). In this work, Al/Ti/Al LMCs with varying Ti layer thickness but a constant number of interface were fabricated by hot rolling and annealing to explore the effect of layer thickness on the enhanced strength and ductility. Ex-situ electron backscatter diffraction (EBSD) and digital image correlation (DIC) techniques were used to reveal the plastic deformation mechanisms. With the decrease of the Ti layer thickness, the extra strength and elongation caused by the layered structure increase continuously until the layer thickness is reduced to ∼0.6 mm. When the best combination of strength and elongation is achieved, the width of the interface affected zone (IAZ) in the Ti layer reaches ∼0.3 mm, which is roughly half of the layer thickness of the Ti layer. Within the IAZ of the Ti layer, more pyramidal and basal slips are activated compared with that in the central part, which contributes to the increase of strain delocalization efficiency. In addition, the geometrically necessary dislocations (GNDs) also exhibit gradient distribution following the strain gradient, resulting in hetero-deformation induced (HDI) strengthening and hardening. This work further enriches the knowledge of achieving excellent strength-ductility synergy in LMCs. [ABSTRACT FROM AUTHOR]

In the present work, the mechanical behavior of tri-metallic 7075Al/1060Al/304 stainless steel (Al/Al/Steel) composites was systematically investigated, emphasizing the effect of the strengthening mechanism introduced by interlaminar and internal microstructures of constituent layers. The results show that the excellent interface bonding of tri-metallic Al/Al/Steel composites was achieved by the combined bonding method of roll-casting and rolling bonding, and the intermetallic compounds were effectively inhibited due to the severe deformation caused by the re-bonding process. It is found that an interfacial transition zone (ITZ) appeared at the 1060Al/Steel interface for all specimens after hot rolling bonding, and the increasing thickness of ITZ can be observed with the increasing rolling reduction. The experimental observation indicated that the ITZ was independent of the intermetallic layer, and its formation was mainly due to the plastic deformation introduced by the shear effect during rolling. Compared with the bi-metallic Al/Steel, the mechanical properties of the tri-metallic Al/Al/Steel composites were significantly improved, which was attributed to the contribution of the high-performance 7075Al with precipitation strengthening behavior according to the rule of mixture. Besides, various annealing treatments were conducted to evaluate the effect of mechanical incompatibility on the mechanical properties of tri-metallic Al/Al/Steel composites. The increasing strain gradient led to considerable dislocation pile-up near the interface of the soft 1060Al layer, inducing an extra strengthening mechanism to the tri-metallic Al/Al/Steel composites, which promoted the optimization of strength and ductility. [Display omitted] [ABSTRACT FROM AUTHOR]

AA 1060/3003/1060 laminated composites were fabricated by hot-roll bonding. The effect of rolling temperature on the microstructure, texture and mechanical properties of AA 1060/3003/1060 laminated composites was investigated. The results show that the development of microstructure and texture through the thickness of Al layers was inhomogeneous in the Al/Al laminated composites. Initial grains were elongated along the direction of about 15° to the RD in the region near the surface layer of AA 1060 aluminum alloy, and the incline angle gradually decreased as the measured position moved towards the interface of 1060/3003 from the surface layer. The rolling texture of 1060 layer consisted of the r-cube and γ-fiber shear textures and the remaining cube component. The r-cube shear texture weakened gradually as the measured position moved towards the interface of 1060/3003 from the surface layer, whereas the center layer of AA 1060 aluminum alloy had the strongest γ-fiber shear texture. The interface layer of AA 3003 aluminum alloy had a completely different texture from the center layer. For the Al/Al laminated composites, the YS and UTS first increased to a maximum value at about 200 °C and then decreased with increasing rolling temperature. [ABSTRACT FROM AUTHOR]

Al 6061/Ti–6Al–4V/Al 6061 laminated composites were fabricated by hot-roll bonding. The effect of rolling temperature and reduction on the microstructure and mechanical properties of Al/Ti/Al laminated composites was investigated. The results show that the Al/Ti/Al laminated composites exhibited a good Al/Ti interfacial bonding. The reduction ratio of Ti to Al layer decreased with increasing rolling temperature and reduction. The development of microstructure through the thickness of Al layer was inhomogeneous. The number of high-angle boundaries and the misorientation angle across low-angle boundaries increased as the thickness position moved towards the surface of Al layer from the interface of Al/Ti. The initial grains near the surface of Al layer were markedly elongated at a certain angle to the RD and then fragmented into the equiaxed fine grains at larger rolling reductions. This inhomogeneity of microstructure can be attributed to the effect of the friction between the roll and sheet surface and the uncoordinated deformation between Al and Ti layers. The deformation inhomogeneity increased with increasing rolling reduction. For the laminated composites fabricated with rolling reductions of 27% and 38%, the yield and tensile strength increased to a maximum value at about 400 °C and then decreased with increasing rolling temperature. The laminated composites fabricated with a 45% reduction possessed lower strength in the temperature range from 400 °C to 450 °C than those with a 38% reduction due to the fracture of Ti layer. [ABSTRACT FROM AUTHOR]

Although laminated metal composites fabricated by accumulative roll bonding (ARB) undergo kink-band formation, there are no guidelines for optimizing their fabrication to avoid necking and shear localization without post-annealing. The necking of the composite layers during rolling generates non-uniformities that may degrade the mechanical performance of the composite. This paper proposes a model for laminated metal composites that aims to quantitatively assess and predict necking based on the work-hardening of each layer. Cu–Al-, Cu–A5052-, and Cu–A5083-laminated metal composites were fabricated using ARB at room temperature (~300 K) without post-annealing, and they were subjected to mechanical and microstructural analyses. A normalized neck amplitude was introduced as a new parameter that accurately predicted the degree of necking observed experimentally. Another new parameter, an instability index , was introduced to frame the necking criterion of the hard layers. A plastic instability criterion framed based on the new parameters accurately predicted the degree of necking in the hard layers of the as-prepared laminated metal composites. These findings may be applied to guide the fabrication of metal composites of any composition using the ARB process. [Display omitted] • Laminated metal composites (LMCs) were fabricated using ARB without post-annealing. • Normalized neck amplitude can assess the experimentally observed degree of necking. • Instability index predicts the necking of the hard layers in the LMCs. • These two parameters aid in framing plastic instability criterion for LMCs. • The findings are instrumental in fabricating stable LMCs using ARB. [ABSTRACT FROM AUTHOR]

Improving the strength and ductility of magnesium (Mg) alloys is a popular area of research. Many studies have indicated that laminated metal composites can be used to simultaneously yield excellent properties of all their constitutive metals. In this study, laminated Mg/Zr (AZ31/Zr702/AZ31) composites were fabricated by hot rolling-induced bonding. An Mg plate was used as the initial wedge component to obtain a wide range of rolling reductions (40%–70%) in a given Mg/Zr composite, and its microstructures and mechanical properties were then characterized. The results show that rolling reduction greater than 40% was needed to achieve a well-bonded interface for Mg/Mg (AZ31/AZ31) and Mg/Zr composites when rolled at 400 °C. With increasing rolling reduction, the strength of the Mg/Zr composite (∼180 MPa) showed no prominent change, and was higher than that of Mg/Mg composites (∼150 MPa) fabricated by using the same bonding process. In addition, the Mg/Zr composite had significantly higher bonding strength (∼6 N/mm) and ultimate peel strength (∼9 N/mm) than the Mg/Mg composites (∼2.5 N/mm and ∼3 N/mm). Finite element simulations were also used to examine the underlying strengthening mechanisms of the composites. The results here contribute to research on the strengthening and toughening of Mg alloys as well as the fabrication of laminated metal composites. [ABSTRACT FROM AUTHOR]

Abstract: Laminated metal composites (LMCs) constructed using Mg and Al have good application potential in the aerospace industry because of their light weights. In this study, two types of LMCs (Mg/Mg and Mg/Al/Mg) with different reduction ratios were prepared via warm roll bonding. Investigations regarding the microstructure and composition of LMCs discovered refined grains in the Mg and Al layers with no intermetallic compounds at the interface. Moreover, tensile and three-point bending tests were conducted to investigate the mechanical properties of the LMCs. The tensile strengths of the two types of LMCs reached their peak values at 35% reduction ratio. The delamination mechanism in LMCs significantly improved the bending properties. However, this effect decreases with increasing reduction ratio. [Copyright &y& Elsevier]

The effects of changing the test temperature from room temperature to 373 or 398 K on the fatigue crack propagation of 6090/SiC/25p-6013 and 7093/SiC/25p-7093 laminates tested in the crack arrestor orientation was investigated. The fatigue crack propagation behaviour of the individual monolithic and discontinuously reinforced aluminium alloy (DRA) layers was additionally compared to that of the laminates. The fatigue behaviour of the laminates was significantly different than that of the individual layers and was affected by changes in the test temperature as well as by a thermal exposure to high temperatures (e.g. 373 or 398 K) before testing at 298 K. Significant changes in the crack velocity also occurred upon traversing from one layer to another for the fatigue tests conducted at high temperature, or after exposure to high temperature. [ABSTRACT FROM AUTHOR]

The effect of processing variables on the growth of a titanium aluminide layer produced from elemental titanium and aluminum foils was examined, with the intention of yielding a titanium–titanium aluminide composite structure. To produce the intermetallic phase in situ, two processing techniques were employed, diffusion bonding and combustion synthesis. Microstructural examination of the titanium aluminide layer revealed striking similarities in the resulting morphology yielded by both processing techniques, in particular for those samples diffusion annealed at lower temperatures (615 °C and below) and those reacted by combustion synthesis. In both cases, an exothermic chemical reaction was responsible for aluminide formation in specimens, and in those samples processed by diffusion bonding, this reaction was observed to be rate controlled by a diffusion mechanism. Chemical analysis of the product aluminide showed the layers to be composed completely of a single phase, TiAl3, which is believed to be the result of thermodynamic stability of this phase relative to other stable equilibrium phases in the titanium aluminum system. The results of these experiments are discussed with a view of utilizing these processes to optimize the mechanical behavior of titanium aluminide by incorporating it into a laminated metal composite. [Copyright &y& Elsevier]

In the present work, laminated Cu/Ni samples reinforced by graphene film with various thicknesses were produced via electrophoretic depositing graphene oxide (GO) on Cu foil by controlling deposition voltage, and the effect of thickness of graphene film on strengthening Cu/Ni multilayer composites were investigated in detail. Microstructural examination revealed that the fragments of graphene film were dispersed at the interface between Cu and Ni layer after hot rolling, with a range of thickness from 0.76 to 5.13 μm. The graphene film showed an excellent strengthening effect in the composites regardless of their thickness according to the tensile testing. However, the toughing effect achieved optimal as the thickness of 4.12 μm. The role of deposited graphene film played in determining the load transfer and optimizing the interface was discussed. Graphene film with appropriate thickness can effectively inhibit the severe asymmetric diffusion behavior of Cu and Ni elements, which plays an important role in strengthening and toughening clad interfaces by inhibiting the formation of Kirkendall voids. This study provides novel insights into understanding the strengthening and toughing behaviors of graphene reinforced multilayer composites, which can be developed into a technical strategy for fabricating high performance laminated metal matrix composites. [ABSTRACT FROM AUTHOR]

Al/Ti/Al laminated metal composites (LMCs), with layer thicknesses ≥800 μm, were fabricated via hot rolling bonding and annealing. The fabricated Al/Ti/Al LMCs displayed improved tensile ductility compared with both the single Ti and single Al layers. Combinational analyses based on digital image correlation and finite element modeling revealed that the width of the interface affected zones (IAZ) could exceed 150 μm, which is more than one order of magnitude larger than previously reported values. The mismatch of plastic anisotropy between the Ti layer and the Al layer may play a crucial role in realizing such a wide IAZ. Slip trace analysis indicated that more pyramidal and basal slips were activated at the Ti/Al interface than in the central part of the Ti layer, which may be attributed to the complex stress/strain state in the IAZ. Although a wide IAZ was observed, the strain hardening capability of the Al/Ti/Al LMCs did not obviously improve. In contrast, the strain rate sensitivity improved, which is assumed to play a key role in the improved ductility of the Al/Ti/Al LMCs. This study can provide a direction for the design of heterostructured materials with high strength and high ductility. • The tensile ductility of Al/Ti/Al thick LMCs is better than monolithic Ti and monolithic Al. • Al/Ti/Al thick LMCs show extra strengthening above the rule of mixture. • The width of interface affected zone in Al/Ti/Al thick LMCs can exceed 150 μm. • Plastic anisotropy may play a crucial role to obtain such wide interface affected zone. • The extra ductility of Al/Ti/Al LMCs may relate with the improved strain rate sensitivity. [ABSTRACT FROM AUTHOR]

AA7075/AA1100 laminated metal composites (LMCs) were successfully produced by accumulative roll bonding (ARB). Also, to investigate the effect of annealing on mechanical properties and microstructure evolution, the composites were subject to annealing treatment at three different temperature (200, 300 and 400 °C) for 1 h. The microstructure evolution was evaluated by scanning electron microscopy (SEM) equipped with an energy dispersive spectroscopy (EDS) and electron back scatter diffraction (EBSD). Tensile tests were performed to measure the mechanical properties of composites. It was observed that elemental diffusion occurred in the constituent layer interfaces, indicating that superior bonding was achieved between the layers with annealing temperature increased. By increasing the annealing temperature, the presentation of a relatively strong {100}<001>Cube recrystallization textures has been attributed to strain-induced boundary migration (SIBM) caused by a preference for the Cube-oriented grains to grow into adjacent S-oriented grains with higher stored energy. In addition, the effect of pre-recovery on anisotropy was discussed in detail. Tensile tests revealed that the plane anisotropy after the two-step annealing (TSA) process was evidently diminished in compare with the single annealing (SSA) process due to the reduced Cube texture strength and the formation of equiaxed crystal structures. • Effect of annealing treatment on microstructure of Al/Al laminated composite was investigated. • The evolution of microstructure and recrystallized texture for different annealing treatment was analyzed systematically. • The mechanical anisotropy of laminated composite was improved by two-step annealing process. [ABSTRACT FROM AUTHOR]

This study presents a method to obtain aluminum alloy laminated composites with high yield strength and good ductility through a multiscale coarse/ultrafine-grained design, which are fabricated by accumulative roll bonding (ARB) and subsequent annealing treatment. Experimental results showed that an outstanding combination of strength and ductility was achieved in 1100/7075 Al alloy laminated composites after annealing at 300 °C for 60 min. Deviation between experimental and predicted results from stress-strain curves indicated that an extra strengthening effect was present in the laminated metal composites. Moreover, to analyze the effect of the magnitude of mechanical incompatibility on the mechanical properties during deformation, laminated metal composites with constituent layers possessing different flow properties were comparatively studied. Laminated metal composites with multiscale grain size distributions were obtained using different rolling strain paths and annealing treatments, which was attributed to differences in the recrystallization of constituent metals. It was determined that cross rolling, compared with direct rolling, gave rise to more effective improvements in the mechanical properties after annealing treatments due to higher mechanical incompatibility across the interface. For the Al alloy laminated composites, the difference in flow properties between the constituent layers plays an important role in additional interfacial strengthening by appropriate collocation of component strengths. During tensile deformation, a high density of geometrically necessary dislocations (GNDs) was distributed in the interface of the soft layer due to the mechanical incompatibility across the interface. The high yield strength with a multiscale interfacial structure is attributed to the back stress strengthening associated with the formation of GNDs and the good ductility results from the high strain hardening rate during plastic deformation. [ABSTRACT FROM AUTHOR]

This study investigates the effect of strain rates and temperatures on the mechanical behavior of ultrasonically consolidated Titanium–Aluminum thin foils to understand and characterize their formability. To this goal, laminated composite samples with a distinct number of layers were bonded using ultrasonic consolidation. Then, tensile and biaxial hydraulic bulge tests at different strain rates and temperature conditions were conducted. The effect of the sample orientation on the mechanical response was also examined. Tensile and hydraulic bulge tests results were compared to observe differences in ultimate tensile strength and strain levels under uniaxial and biaxial loading conditions. The effects of loading condition, strain rate, and temperature on the material response were analyzed and discussed on the basis of test results. In general, it was concluded that the maximum elongation values attained were higher for the samples subtracted along the sonotrode movement direction compared to those obtained from the normal to sonotrode movement direction. The elongation was obtained as high as 46% for seven bi-layered samples at high-temperature ranges of 200–300 °C. Hydraulic bulge test results showed that elongation improved as the number of bi-layers increased, yet the ultimate strength values did not change significantly indicating an expansion of the formability window. [ABSTRACT FROM AUTHOR]

Abstract Direct alloying is very difficult for immiscible alloy systems owing to the absence of driving force at equilibrium. To realize alloying for immiscible alloy systems, a method, named as irradiation damage alloying (IDA), is developed and used to prepare W/Ag, Mo/Ag and Mo/Cu laminated metal composites (LMCs) in this work. The IDA process mainly includes three steps: firstly, the multi-energy Ag (or Cu) ions were implanted into the surface of the W (or Mo) matrix; secondly, an Ag (or Cu) coating layer was deposited on the damaged W (or Mo) matrix by vacuum evaporation; thirdly, the obtained W/Ag (Mo/Ag or Mo/Cu) laminated bimetallic samples were annealed at 950 °C in hydrogen for 8 h. It is confirmed that diffusion alloying of immiscible metal atoms indeed takes place and metallurgical bonding interfaces have been constructed successfully. Additionally, to reveal the underlying mechanism of IDA, a thermodynamic model is introduced. It is shown that the storage energy caused by irradiation damage in the matrix metal and the surface energy of the coating layer dominate the thermodynamic driving force. Besides, the storage energy has been confirmed to play a decisive role for the microstructure development of the metallurgical bonding interface. Graphical abstract Unlabelled Image Highlights • The newly developed IDA is a feasible way to realize direct alloying for immiscible systems. • W/Ag, Mo/Ag and Mo/Cu metallurgical bonding interfaces have been constructed successfully by means of IDA. • The storage energy caused by irradiation damage and surface energy of coating layer dominate thermodynamic driving force. • The decisive role for the microstructure development is the storage energy caused by irradiation damage. [ABSTRACT FROM AUTHOR]