TWI

Technology improvements and process innovations in respect of friction stir welding (FSW) of high temperature materials are reviewed, welding process conditions and mechanical properties of completed welds for various alloys using polycrystalline cubic boron nitride (PCBN) tools are summarised, and applications to stiffened structures, underwater FSW and linepipe FSW in steels are demonstrated. Details of PCBN tool design are reviewed including selection of the grade of PCBN, design of the pin tool, and tool life. Test welding results are reported for welds made using PCBN tools on ferritic steels (A-36, QT C-Mn steel, DH-3, HSLA-65, L-80, X-80 and X-120), Dual Ten 590 dual-phase steel, austenitic stainless steels 304L, 316L, 301L and AL-6XN, Type 430 stainless steel, SAF 2507 (UNS S32750) super duplex stainless steel, Ni-base alloys (Alloy 201, Alloy 600, Alloy 718), and some speciality alloys (Narloy Z, cast NiAl bronze, Invar). Other issues discussed include tooling to allow FSW of T-joints to attach stiffeners to panels, friction stir spot welding on automotive steels, underwater FSW of type 304L stainless steel, and welding of 300 mm diameter steel pipe using a special FSW pipe welding machine.

5th International Symposium, 14-16 Sep 2004, Session 6A: Steel, Paper 03