OBRABOTKAMETALLOV technology Vol. 25 No. 3 2023 Introduction Influence of Roughness of Contact Surfaces on Bonding of Materials under Plastic Deformation Bond strength between dissimilar materials is the most important characteristic of laminated composites, which determines the success of its development for industrial production [1].Among the known technologies for the production of laminated metal composites (explosion welding, cold roll bonding, powder coating, etc.), the most promising technologies are based on cold roll bonding due to the high process efficiency, the possibility of automation, and the relative ease of quality control. Compared with widespread explosion welding, laminated composites formed by deformation have higher accuracy, quality and stability of properties and a lower level of harmful tensile residual stresses. A limiting factor in the development of production of laminated composites by rolling and other methods based on pressure is the problem of obtaining strong bonding between its layers [2]. Due to the complexity of ongoing physical and chemical processes at the interlayer boundary during plastic deformation, the determination of pressing modes is a laborious task for each new composite to be developed. As a result, the development of new technologies inevitably involves extensive experimental work. Currently, a large number of studies on the influence of various factors of cold roll bonding on the bond strength between materials have been conducted [3–8]. Jamaati and Toroghinejad [3] and Li et al. [4] presented fairly detailed review papers describing the influence of factors on the bond strength between similar and dissimilar metals during cold roll bonding. In particular, Jamaati and Toroghinejad [3] determined the effect of reductions, annealing before and after rolling, initial sheet thickness, rolling speed, rolling direction, friction coefficient, and the presence of hardening particles. Li et al. [4] considered the effect of such rolling conditions as reduction, deformation zone parameters, the presence of contaminants and the thickness of the oxide film on the surfaces to be bonded, method of surface preparation, friction conditions, and post-annealing. Review [3, 4] and experimental [9–17] works show that the preparation technology of contact surfaces of materials is one of the most significant factors influencing the process of its joining. Surface treatment is necessary to remove particles of moisture, grease and contaminating, as well as to reduce the thickness of surface oxide films that prevent bonding of materials. It is important to note that the optimal parameters of contact surfaces for joining materials are still unknown from the published works: the arithmetic mean roughness Ra, the height of asperities H, the mean step of asperities along the vertices S, the wavelength of asperities W, etc. For example, in [9], the highest strength of the steel-aluminum joint was obtained for surfaces with a roughness Ra of 5.8 µm among the possible options of Ra: 1.7, 1.8, 1.9, 3.6, 4.2 and 5.8. The worst result was observed for surfaces with a roughness Ra equal to 1.8. In [10], the maximum bond strength between brass and IF steel was obtained for a roughness Ra of the contact surfaces of 4.2 μm among six options of roughness of the contact surfaces: 0.5, 1.7, 2.2, 2.9, 3.6 and 4.2 µm. The worst result was when the roughness of the contact surfaces was 0.5 µm. In the works presented above, it was concluded that the greater the roughness of the contact surfaces, the higher the achievable bond strength between materials. The following are works in which this conclusion is not confirmed. In [11], the best quality of the bonding between pure aluminum and aluminum alloy AA2024 was observed for contact surfaces with a roughness Ra of less than 0.58 µm among the possible options of 0.58, 0.13 and 0.03 µm obtained by microengineering of surfaces, as well as 0.05 and 0.25 mm obtained by macroengineering. The worst quality was observed for surfaces with a roughness Ra equal to 0.2 mm. In [12], the highest bond strength between pure aluminum and AA2024 alloy was achieved at a contact surface roughness Ra of 1 µm among the options: polished surface, Ra = 1, 3 and 5 µm. The worst result is obtained for a polished surface. In [13], the maximum bond strength between sheets of commercially pure copper was achieved when the roughness of contact surfaces Rz was 0.09 µm among the options of Rz = 0.09, 1.5, 4.4 and 14 µm. It was also found out in the work that the greater the ratio of the height H to the asperity base width W of the
RkJQdWJsaXNoZXIy MTk0ODM1