Quenching During Thermomechanical Joining Using Friction Spun Joint Connectors <jats:title>Abstract</jats:title> <jats:p>Mechanical joining processes have played an increasingly important role in the manufacturing of modern lightweight structures due to a greater variety of materials. The growing number of joining tasks requires a large number of joining elements. Friction spun joint connectors (FSJC) offer an innovative approach that meets the growing demand for flexibility. This process combines rotational movement and axial force to create targeted friction heating, enabling the production of FSJCs and the joining of various sheet metal materials. The shape of the FSJC can be optimally adapted to the joining situation in question, providing a significant advantage in terms of process chain versatility. This paper investigates FSJCs made of the steel grades C45E+C (1.1191) and 115CrV3 (1.2210), the effect of in situ quenching during the joining process. The influences of the essential parameters of rotational speed, feed rate, and FSJC length on the mechanical properties after quenching are being focused on and compared to similar conditions during joining without quenching. At the same time, the material change is analyzed to determine the effect of different alloy approaches on hardness profiles and strength characteristics in cross-tensile testing. For this purpose, systematic test series with varying process parameters are conducted and evaluated using hardness measurements and cross-tensile tests.</jats:p> 79 6 Springer Science and Business Media LLC