Investigation of the joinability of the high-strength aluminum alloy AA7075 in shear-clinching processes

Wiesenmayer, Sebastian; Merklein, Marion

doi:10.1177/14644207211067935

Cited by 4 publications

(4 citation statements)

References 16 publications

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“…Due to the enhanced material flow at the beginning of the process, the material volume in the joining zone is reduced, resulting in a decline in the residual bottom thickness. 21 The lower strength also leads to the increased penetration of the upper sheet by the outer punch. 21 Therefore, the upper neck thickness t un is reduced.…”

Section: Resultsmentioning

confidence: 99%

“…21 The lower strength also leads to the increased penetration of the upper sheet by the outer punch. 21 Therefore, the upper neck thickness t un is reduced. As the lower neck thickness t ln is measured between the imprint of the inner punch and the smallest diameter of the cutout hole in the lower sheet, this feature remains on a comparable level for the three different heat treatment temperatures.…”

Section: Resultsmentioning

confidence: 99%

“…The negative effect on the joint formation can be explained with the enhanced radial material flow of the upper sheet during the joining sequence and the resulting reduction of the material volume in the joining zone. 21 As a result, characteristic geometric features, which are critical for the joint strength, become smaller.…”

Section: Resultsmentioning

confidence: 99%

“…A similar observation was done by the authors in a previous work, in which AA7075 in a paint-baked condition could be joined with crack initiation. 21 Yet, the highest forces of the tested conditions could be transmitted under shear load. However, under tensile load, the handling strength was hardly exceeded.…”

Section: Joint Characteristicsmentioning

confidence: 93%

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Shear-clinching of the high-strength aluminum alloy AA7075 with laser-assisted retrogression

Wiesenmayer

Merklein

2022

Proceedings of the Institution of Mechanical Engineers, Part B:

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Due to their extraordinarily high specific strength, aluminum alloys of the 7000 series are coming into focus of car manufacturers. In an aged state, the limited formability of the alloys poses a challenge for joining by forming processes, which are of particular importance for the realization of multi-material lightweight structures. The innovative shear-clinching technology has proven to be suitable for joining die-sided high-strength steels and punch-sided aluminum alloys. Yet, the process is limited by the formability of the upper joining partner. Due to the high strength of AA7075 in the artificially aged T6 temper, the material flow is obstructed during the joining sequence and failure occurs. The formability of the hardenable alloy can be enhanced by the performance of short-term heat treatment prior to joining. For this purpose, a laser is a suitable heat source, allowing the effective heating of small areas. Within this study, the influence of the temperature during the heat treatment with a diode laser on the material properties of AA7075 is investigated by uniaxial tensile tests and metallographic analyses. Moreover, the joinability of the alloy as well as the resulting joint formation and strength in dependence on the process control during the heat treatment are analyzed. Softening of the alloy enhances with increasing heat treatment temperatures. However, in comparison to the T6 temper, the ductility does not increase. For temperatures of 300 °C and higher, the joinability of AA7075 after the heat treatment is given. Still, for 300 °C cracks are initiated, compromising the joint quality. Despite the occurrence of cracks, the highest joint strength is achieved after a heat treatment at 300 °C, as for higher temperatures, the material’s strength becomes distinctly lower.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Joint Characteristicsmentioning

confidence: 93%

See 2 more Smart Citations

Shear-clinching of the high-strength aluminum alloy AA7075 with laser-assisted retrogression

Wiesenmayer

Merklein

2022

Proceedings of the Institution of Mechanical Engineers, Part B:

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A review on mechanical and metallurgical joining by plastic deformation

Kasaei

Beygi

Carbas

et al. 2023

Discov Mechanical Engineering

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The substitution of traditional materials with lightweight materials in vehicle structures requires the development of new joining techniques which are capable of joining un-weldable alloys as well as dissimilar materials. Although conventional joining techniques such as fusion welding, adhesive bonding and mechanical fastening have matured in recent decades, their use for some of the above applications is limited. In this paper, recently developed joining techniques based on plastic deformation are presented and discussed. These techniques are divided into two categories, those based on mechanical interlocking and those based on metallurgical bonding. The first category covers clinching, self-pierce riveting and some innovative joining methods, and the second category covers friction stir welding and its variants. The focus of this study is on process development, process control and monitoring, process modelling, and joint characterization techniques. Finally, the two categories are compared, and their potential is discussed.

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Mechanical joining of high-strength multi-material systems − trends and innovations

Merklein

Jäckisch

Kuball

et al. 2023

Mechanics & Industry

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In conjunction with mechanical joining processes. Mechanical joining processes play a key role for the realization of multi-material lightweight structures, which are essential with regard to environmental protection. However, joining of dissimilar high-strength materials is challenging due to the varying properties of the joining partners and due to their high flow stresses and often limited ductility. Thus, the evolution of established processes as well as the development of innovative and highly productive joining technologies are necessary. Requirements for a highly volatile production environment are versatility, flexibility, resilience and robustness. Within this contribution, current trends and innovations related to selected mechanical joining processes for enabling the material mix are outlined in order to point out opportunities to address these requirements in the future. In this context, joining using cold formed pin structures is presented as a promising approach for connecting dissimilar materials like metals to fibre-reinforced plastics. Furthermore, it is shown how the shear-clinching technology can be combined with a process-adapted application of locally limited heat treatment in order to promote the joinability and control the material flow during joining. A novel approach for reducing process forces and expanding process windows is the use of ultrasonic assistance for mechanical joining operations, which is demonstrated by the example of a nut staking process with superimposed high frequency oscillation. As concerns the widely used self-piercing riveting technique, current research activities relate not only to the further development of the joining process itself, for example by combining self-piercing riveting and tumbling, but also to the use of new rivet materials like high strain hardening stainless steels. In addition, the evolution towards mechanical joining 4.0 against the background of data-based process control in conjunction with of mechanical joining processes is also subject of the considerations.

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Investigation of the joinability of the high-strength aluminum alloy AA7075 in shear-clinching processes

Cited by 4 publications

References 16 publications

Shear-clinching of the high-strength aluminum alloy AA7075 with laser-assisted retrogression

Shear-clinching of the high-strength aluminum alloy AA7075 with laser-assisted retrogression

A review on mechanical and metallurgical joining by plastic deformation

Mechanical joining of high-strength multi-material systems − trends and innovations

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