Abstract: An apparatus and method for producing a fatigue resistant friction/inertia welded joint in a part with hollow cylindrical cavity(s). Hollow cylindrical sleeve(s) are press fit into the cavity(s) prior to the application of the conventional steps of friction/inertia welding. The joint created is fatigue resistant due to the sequence of flash flowing into the hollow portion of the inserted sleeve, deflecting the end of the inserted sleeve inward, forming a radius and eliminating the possibility of the interior flash bonding to or notching the interior wall(s) of the part. This method eliminates potential stress risers by achieving both ideal flash formation and interior cavity shielding.