TWI

Friction stir processing (FSP) experiments were undertaken on annealed AISI 420 stainless steel plates (thickness 6 mm) in order to compare three methods for assessing tool wear. The investigations incorporated two tool compositions (WC-Co or polycrystalline BN), three tool designs (domed, round-bottomed cylindrical pin and tri-flute) and varied FSP parameters, such as traverse speed (150-300 mm/min), shoulder plunge depth (0.1 or 0.2 mm) and tool tilt angle. The wear assessment techniques involved: use of a synthetic rubber compound to create in situ replicas of a WC-Co tool subsequently measured using 3D optical microscopy; using the same combination of replica and 3D imaging to measure changes in polycrystalline BN tool surface roughness; and an X-ray radiography approach to locate tool debris within the stir zone and so identify fracture events.

9th International Symposium, 15-17 May 2012, Session 3B: FSW Tools, Paper 04