Analysis of extruded pins manufactured by friction stir forming for multi-material joining purposes (original) (raw)
Related papers
Mechanical Joining Utilizing Friction Stir Forming
Materials Science Forum, 2021
The material ratio of steel in automobiles will likely decrease rapidly in the next decade with the advent of electric vehicles, which will promote the multi-materialization of parts. Hence, recently, researchers have successfully studied technologies for joining dissimilar materials. The authors have studied the joining of dissimilar materials by using the friction stir forming (FSF) approach. In the FSF process, a substrate material was first placed on a die. Next, friction stirring was conducted on the back surface of the material. The material then deformed and filled the cavity of the die because of high pressure and heat caused by the friction stirring. The authors utilized the FSF approach to generate mechanical joints between dissimilar materials. In this paper, the author introduces various techniques for joining dissimilar materials through FSF.
Journal of Mechanical Science and Technology
A new spot joining process called dieless friction stir extrusion is proposed, in which simultaneous mechanical interlocking (collar formation) and metallurgical bonding is the key aspect of joint formation. The pinless flat stir tool eliminates pinhole and hook formation, the common defects of friction stir spot welding. Aluminum alloy sheets such as AA 5052-H32 and AA 6061-T6 are spot joined and the effect of change in tool shoulder diameter (10-18 mm) on joint strength and joint formation is evaluated. Lap shear fracture load of 6.22 kN obtained at optimum tool shoulder diameter of 14 mm is higher than that of conventional spot joining techniques. Macrostructure analysis revealed that increase in tool shoulder diameter results in poor mechanical interlocking. Consequently, pin shear failure is common at highest tool shoulder diameter. Critical weak zones of failure are identified. The change in tool shoulder diameter has significant impact on the external joint morphology.
Mechanical joining without auxiliary element by cold formed pins for multi-material-systems
Nucleation and Atmospheric Aerosols, 2019
In order to achieve sustainable and resource-saving products, the use of intelligent lightweight design is a current trend. One approach is the implementation of multi-material systems. However, the joining technology poses a key challenge when combining different materials like continuous fibre-reinforced thermoplastic composites (CFRTP) and metal or joining steel and aluminium. Due to different material properties and partial chemical incompatibilities, established joining techniques without auxiliary element, like welding or clinching, are reaching their limits. Joining dissimilar materials through pin structures has proven as a possible strategy to produce hybrid multi-material systems on a laboratory scale. Nevertheless, this technology is hardly used in mass production due to the currently complex, uneconomical pin manufacturing process. In this work, cold forming is presented as a promising approach for the production of such pins. In a first step, the pins are extruded from a steel sheet (DC04). In a second step, the steel sheets are joined with aluminium (EN AW-6016) or CFRTP by either pressing pins directly into the material or by caulking pins with a pre-punched joining partner. The material for the pin is extruded directly from the sheet metal thus preventing additional weight in contrast to fasteners. In addition, the direct press-fit is a suitable method to achieve a tightly sealed joint. Within this work, the extrusion of the pin, as well as the two different joining operations, are investigated showing the fundamental applicability and the potential of the new joining process. In order to analyse the applicability of the joining operation shear tensile tests are conducted.