Friction Stir Welding at TWI

Introduction

In late 1991 a novel and potentially world beating welding method was conceived. The process was duly named friction stir welding (FSW), and TWI filed for world-wide patent protection in December of that year. Consistent with the more conventional methods of friction welding, which have been practised since the early 1950s, the weld is made in the solid phase, that is no melting. Since its invention, the process has received world-wide attention and today many companies around the world are using the technology in production, particularly for joining aluminium alloys.

Friction Stir Welding

In friction stir welding (FSW) a cylindrical, shouldered tool with a profiled probe is rotated and slowly plunged into the joint line between two pieces of sheet or plate material, which are butted together. The parts have to be clamped onto a backing bar in a manner that prevents the abutting joint faces from being forced apart. Frictional heat is generated between the wear resistant welding tool and the material of the workpieces. This heat causes the latter to soften without reaching the melting point and allows traversing of the tool along the weld line. The plasticised material is transferred from the leading edge of the tool to the trailing edge of the tool probe and is forged by the intimate contact of the tool shoulder and the pin profile. It leaves a solid phase bond between the two pieces. The process can be regarded as a solid phase keyhole welding technique since a hole to accommodate the probe is generated, then filled during the welding sequence.

• FSW - Symposia:
  Seventh 2008, Sixth 2006, Fifth 2004, Fourth 2003, Third 2001, Second 2000, First 1999
• FSW - Process Advantages
• FSW - Materials and Thicknesses
• FSW - Superior Weld Quality
• FSW - Joint Geometries
• FSW - Applications
• FSW - Equipment
• FSW - Intellectual Property Rights

Please fill in the enquiry form or contact friction@twi.co.uk for FSW enquiries or for comments about these Web pages.