Devices, systems, and methods for increased wear resistance during low temperature friction stir processing

A friction stir processing tool rotatable around a central rotational axis, the friction stir processing tool comprising:

• a single body monolithically formed of polycrystalline diamond;
• a shoulder of the single body extending transverse to the central rotational axis;
• a lower pin of the single body extending downwardly from the shoulder;
• the lower pin having a lowermost end and a side surface extending around the pin;
• a discontinuity in the side surface of the lower pin;
• a working surface of the shoulder extending around the lower pin;
• an arcuate ridge extending downwardly from the working surface of the shoulder and extending less than 360 degrees around the lower pin, the arcuate ridge having opposite ends with a spacing therebetween;
• the discontinuity in the side surface of the lower pin facing radially outward toward the spacing in a radial direction between the opposite ends of the arcuate ridge;
• an upper surface portion of the single body opposite the lower pin, the upper surface portion extending transverse to the central rotational axis;
• the single body having a total length extending along the central rotational axis from the lowermost end of the lower pin to the upper surface portion of the single body;
• and
• the polycrystalline diamond extends the total length of the single body tool.