Dissimilar Joining of Steel to Aluminium for Automotive Applications - Detailed Review of Mechanical Fastening and Adhesive Bonding
By Sullivan Smith
Industrial Need
This report provides a detailed set of data for mechanical joining and adhesive bonding of steel to aluminium for automotive applications. It includes an experimental study, technical process details, information on how a given process can be applied across a range of materials, mechanical properties and physical characteristics of the joints produced, and an economic study. The aim of the report is to provide a highly detailed set of data covering the major factors that a company needs to consider when selecting a joining technology. This will enable the reader to determine the most appropriate joining solution for a material combination within their own specific economic and performance related constraints. The report also includes a study on the development of a resistance spot welding solution for steel to aluminium joining.
Key findings
- No single mechanical joining process is capable of joining a full range of dissimilar steel and aluminium material combinations. For a complex body-in-white (BIW) construction, multiple processes must always be used.
- The mechanical strength of joints made by certain joining processes was considerably higher than others. This was observed in both tension and shear loading. However, critically, when a structural adhesive was used in a joint, the strength in shear loading of joints made by all the processes was improved significantly. Considering all major original equipment manufacturers (OEMs) use adhesive in dissimilar joints (for reasons of mechanical performance and corrosion protection), the use of high-speed low cost processes appears to be very attractive in applications where shear is the main loading mode. Larger, more expensive fasteners such as blind rivets or Flow Drill Screw (FDS) should only be used in applications where high tension strengths are required, or where another clear process advantage, such as single sided access, is beneficial.
- A large difference in speed, cost, robot payload, joint size and mechanical performance exists between the various joining technologies available. The user must strike a balance of performance, economics and quality when selecting a process.
Cross-section of a Flow Drill Screw joint.
Cross-section of a clinch rivet joint.