Development of a Testing Procedure to Determine the Bond Strength in Joining-by-Forming Processes

Abstract

Roll bonding is a joining-by-forming process, in which two or more metals are permanently joined through pressure and plastic deformation, which causes the creation of a metallic bond. The bond formation is a complex process based on various process conditions in the joining zone, such as strain, normal pressure, temperature, strain rate, shear strain and surface condition. Since an individual variation and analysis of the influencing parameters is usually not possible during the rolling process, a specific experimental setup for the investigation of the joining mechanisms is necessary. In this paper, a testing procedure has been developed to determine the bond strength in joining-by-forming processes. The material combination chosen was AA2024/AA1050 as used in aircraft applications. AA2024 sheets are cladded with pure aluminum to improve the corrosion resistance. The performed experimental parameter study confirms the expected influencing factors and is used to determine parameters of a bonding model, which can be integrated in a finite element simulation.

Bonding Experiments at Elevated Temperatures: The Effect of the Sample Storage Time on the Bond Strength of Metals

“…For the determination of the effect of the sample storage time on the bonding behavior of metals, bonding experiments at 450 and 1100 °C were conducted. These tests were carried out on a torsion plastometer type STD 812 from TA Instruments (see Figure 1 left) according to the technique developed by Mikloweit et al [ 3 ]…”

“…Within the Institute of Metal Forming (IBF), a test procedure has been established, which can be used for various joining‐by‐forming processes, e.g., roll bonding or composite ring rolling. [ 3 ] At the same time, this characterization method can be used to investigate various factors influencing the bond strength, such as the surface condition, temperature or compression force, or even the material healing mechanism of void closure during open‐die forging. [ 6 ]…”

“…In addition, complex phenomena, such as bond formation, failure, and strength, can be simulated by a wide range of models within the FEA. [1][2][3][4][5] However, the accuracy of an FEA strongly depends on the quality of the input parameters and boundary conditions, which must be as equal as possible to the real industrial process. Therefore, it is necessary to determine the corresponding bonding strength for each bonding condition, which also contains the storage time.…”

“…Within the Institute of Metal Forming (IBF), a test procedure has been established, which can be used for various joining-by-forming processes, e.g., roll bonding or composite ring rolling. [3] At the same time, this characterization method can be used to investigate various factors influencing the bond strength, such as the surface condition, temperature or compression force, or even the material healing mechanism of void closure during open-die forging. [6] Although the influence of several process parameters, e.g., surface condition on the bond formation and the resulting bond strength, was intensively investigated in a wide variety of publications and can be examined with this testing procedure, the effect of sample storage time and the resulting oxidation at environmental conditions were seldom focused of this research.…”

“…[6] Although the influence of several process parameters, e.g., surface condition on the bond formation and the resulting bond strength, was intensively investigated in a wide variety of publications and can be examined with this testing procedure, the effect of sample storage time and the resulting oxidation at environmental conditions were seldom focused of this research. [3] Commonly known examples were only available for aluminum and short storage times. [7,8] Therefore, the present work addresses this issue to further improve the experimental bond strength determination by using the test procedure according to Mikloweit et al [3] and extending it to include the effect of the sample storage time.…”