The aim of this work is to study the influence of the shoulder geometry on friction stir welding of 1
mm-thick copper-DHP plates. The welds were produced using three different shoulder geometries,
flat, conical and scrolled, and varying the rotation and traverse speeds of the tool. The flat shoulder
tool proved to be inadequate for performing welds, because many defects were produced for all
welding conditions. In turn, the scrolled shoulder tool is more effective than the conical one in the
production of defect free welds. However, both geometries required a minimum rotational speed to
avoid internal defects. For the same welding parameters, greater grain refinement, higher hardness
and improved strength are also achieved in the nugget of the welds, using the scrolled tool
