Two kinds of variant of friction stir welding (FSW) process: friction stir brazing (FSB) and friction stir spot brazing (FSSB)

摘要

Friction stir lap welding (FSLW) cannot provide excellent results in dispersing oxide film and mixing extent like friction stir butt welding. Additionally, FSLW suffers from hook formation and small welded area for one pass. To expulse oxide film with liquid phase and then extend bonded area and to eliminate hook formation, two kinds of variant of FSW process of friction stir brazing (FSB) and friction stir spot brazing (FSSB), in which a pinless tool and braze are used, were developed by the present author. For instance, FSB of Al/steel dissimilar assembly using Zn foil braze and FSSB of steel/Ti dissimilar assembly using Cu foil braze were attempted. For FSB of Al/Steel using a special pinless tool with large shoulder of 65 mm diameter, Zn braze foil was melted and expulsed, bonding was established by intimate contact at central region and intermetallic compound layer of 16 um at outer region. For FSSB of steel/Ti assembly, intimate contact and quite thin eutectic reaction layer of 2 μm were achieved at steel/Cu and Cu/Ti interface, respectively.