Influence of the Production Process on the Binding Mechanism of Clinched Aluminum Steel Mixed Compounds

Abstract

The multi-material design and the adaptability of a modern process chain require joining connections with specifically adjustable mechanical, thermal, chemical, or electrical properties. Previous considerations primarily focused on the mechanical properties. The multitude of possible combinations of requirements, materials, and component- and joining-geometry makes an empirical determination of these joining properties for the clinching process impossible. Based on the established and empirical procedure, there is currently no model that takes into account all questions of joinability—i.e., the materials (suitability for joining), design (security of joining), and production (joining possibility)—that allows a calculation of the properties that can be achieved. It is therefore necessary to describe the physical properties of the joint as a function of the three binding mechanisms—form closure, force closure, and material closure—in relation to the application. This approach illustrates the relationships along the causal chain “joint requirement-binding mechanism-joining parameters” and improves the adaptability of the mechanical joining technology. Geometrical properties of clinch connections of the combination of aluminum and steel are compared in a metallographic cross-section. The mechanical stress state of the rotationally symmetrical clinch points is qualified with a torsion test and by measuring the electrical resistance in the base material, in the clinch joint, and during the production cycle (after clinching, before precipitation hardening and after precipitation hardening).

Design of clinched joints on the basis of binding mechanisms

“…The force-closure component and material-closure component are independent of the direction of loading. These testing methods where introduced and qualified in [17] to detect the change of force-closure component within the process chain by using an aluminum steel mixed compound due to precipitation hardening of the aluminum alloy EN AW 6014.…”

“…After the precipitation hardening process, the specific resistance of the components degreases. Zhang presents this effect in [26] at an Al-Mg-Si Alloy and a measurement in [17] at a homogenous conductor of the investigated aluminum alloy EN AW 6014.…”