RESEARCH ARTICLE Applicability of friction stir welding in polymeric materials

The applicability of friction stir welding has been studied on polypropylene sheets. The joint strength has been analysed in terms of rotation and translation speed. It has been demon-strated that in addition to the judicious selection of welding pa-rameters the proper construction of the welding tool is also very important. The crystallinity of the seam and its neighbourhood has been analysed by DSC, the structure of the seam border region has been analysed by optical and by scanning electron microscopy. It was found, that the seam has undergone embrit-tlement, as a result of non-satisfactory homogenization. Having analysed the flow circumstances during welding on seams pro-duced by proper tool geometries it has been demonstrated that homogenization and, consequently the joint strength can be sub-stantially improved