Establishing W-Based Friction Stir Welding Tool Life for Thick Section Steel Applications

Recently, Friction Stir Welding (FSW) has been demonstrated as a solid-state welding technology capable of joining thick section steel in a single pass. This process’s ability to reduce cycle time and manpower as opposed to traditional joining methods creates an opportunity to significantly reduce the cost of welding thick section steels. Open literature has recently indicated a 25% cost reduction if FSW can be applied to offshore pipe line construction. This study was initiated to establish a robust tool design capable of joining 19-mm (0.75-in) X-70 steel, maximize tool life, and identify cross weld mechanical properties throughout the life of the tool. This presentation will summarize trends identified during tool life testing and the mechanical properties observed as the tool wore. Over 59-m (193-ft) of weld length was realized with a single W-based tool and the ultimate tensile strength throughout welding was near matching to the base metal.