Patent ID: 8434661

Claim:
A method for forming a lap weld between at least two dissimilar materials, the method comprising the steps of: providing a friction stir welding tool comprising a shoulder, a pin extending from the shoulder, and a scribe cutter extending from the terminal end surface of the pin in an offset position wherein the terminal end surface is perpendicular to the longitudinal direction of the tool; stacking the dissimilar materials comprising a first material and a second material in a lap weld stack with an overlap therebetween defining a weld interface of a preselected width along the length between the materials being joined; penetrating through the first material of the lap weld stack to a preselected depth with the pin and the scribe cutter, the pin only penetrating into the first material and the scribe cutter penetrating through the first material and into the second material; wherein the scribe cutter cuts a surface of the second material to introduce a plurality of features therein along the length of the weld interface; and backfilling the features with extruded first material forming mechanically interlocking features along the length of the interface that yields a lap weld with an enhanced shear strength between the dissimilar materials.