Method and device for the friction stir welding of two components

A method for friction stir welding of two components in butt weld configuration, the method comprising:

• positioning the two components relative to one another in such a way that a connection region is formed in a butt joint between the two components;
• friction stir welding the two components by a friction stir welding tool which penetrates the connection region in its depth in order to produce a weld configured as a butt weld which permeates the connection region with formation of an unpenetrated weld edge portion of the connection region, wherein the weld edge portion has not been penetrated by the friction stir welding tool, wherein the friction stir welding tool penetrates the connection region in its depth starting from a first surface of the components, wherein the friction stir welding tool does not fully penetrate the connection region in its depth but only as far as the weld edge portion;
• and
• introducing internal compressive stresses, at least in the weld edge portion of the connection region which has not been penetrated by the friction stir welding tool, in chronologically staggered manner with regard to formation of the weld, wherein the internal compressive stresses are solely introduced from a second surface of the components, wherein the second surface is arranged opposite the first surface and adjacent the weld edge portion, wherein the internal compressive stresses are generated by laser shock peening.