OBRABOTKAMETALLOV technology Vol. 25 No. 3 2023 Introduction Over the past decades, laminated composites based on aluminum alloys have been increasingly used in the aerospace and automotive industries [1]. Due to the use of different materials in one part, it is possible to combine such properties as strength, corrosion resistance, specific weight (which is important for aviation), and thermal conductivity, etc. Laminated composites are usually produced by accumulative roll bonding, duringwhich themetallurgical joining of preliminarily prepared sheets occurs [2]. Accumulative roll bonding technology includes the following main stages: preparation of sheet surfaces to be bonded by chemical and mechanical treatment; sheets packing and fixing by welding or riveting; rolling of the pack according to the specified schedule; heat treatment; and cutting off the fixed edges of the pack. These operations can be followed by sheet stamping operations, such as cutting and drawing [2]. The principal purpose of accumulative roll bonding is to obtain reliable bonding between materials characterized by strength and evaluated through special tests [3]. However, at this moment, the joining processes of similar and dissimilar materials by plastic deformation are still poorly understood. This is confirmed by numerous works devoted to the study of the influence of individual technological factors of accumulative roll bonding on the bond strength between materials’ layers [1–10].Analysis of review [2, 4, 5], experimental [4–10] and theoretical [11, 12] works showed that the most significant factors of accumulative roll bonding are thickness reduction and pressure during rolling, surface preparation technology for joining and the ratio of strength properties of materials to be bonded. Due to the lack of reliable models for predicting the conditions under which the bonding of materials begins, the development of technologies to produce new laminated composites is accompanied by a large amount of preliminary experimental research. As shown in the previous work of the author [3], additional difficulties are caused by the unequal influence of the same factors on the process of joining materials, which depends on the combination of materials in a particular technological process. For example, in some cases, an increase in the roughness of the contact surfaces contributes to bonding; in other cases, on the contrary, it prevents bonding. To describe the mechanism of bonding of similar and dissimilar materials, there are approximately six theoretical models described in [13]. The most frequently cited model is Bay’s theoretical model of materials’ bonding [14], which describes bonding of materials as a four-stage process: (1) cracking of surface oxide films, (2) extrusion of pure metals into cracks between oxides, (3) interatomic interaction of pure metals, and (4) formation of “bonding bridges”. The limitations of Bay’s theoretical model are the assumptions typical for continuum mechanics: two-dimensional formulation, uniformity of flow of layer materials and pressures in the deformation zone, etc. In addition, Bay’s model does not allow one to determine analytically the level of deformations and pressures during rolling, which is necessary to initiate bond formation. In this regard, in recent years, methods of finite element (FE) simulation of the processes of joining materials have undergone great development [15–19]. Based on full-scale experiments, it is possible to reproduce the conditions under which bond formation between materials occurs. In particular, for the analysis of processes of materials’ bonding, such characteristics as normal pressures, shear stresses, relative average normal stresses, and effective strains are of interest. The most detailed FE analysis of the rolling process of aluminum composite was provided by Khaledi et al. [17–18]; however, they simulated the process of similar aluminum sheets bonding, which was well studied in the experimental works of Bay [14]. Study of the mechanism of bonding between dissimilar materials is a more difficult task. Therefore, the aim of this work was to establish a relationship between the stress-strain state parameters and the formation of a stable bond between aluminum alloys of different compositions. To achieve this aim, the following tasks of the work are formulated: 1. Simulation of the rolling process of the laminated composite “AMg3/D16/ AMg3” with the initial data corresponding to the physical experiments carried out at IES Ural Branch of the Russian Academy of Sciences; 2. Selection and analysis of the most important stress-strain state parameters during rolling of laminated composite “AMg3/D16/AMg3”.
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