TWI

Friction stir welding (FSW) was conducted on high-strength pipe steel plates (thickness 12.7 mm) using commercially pure tungsten, tungsten-rhenium (W, 25%Re) and polycrystalline cubic boron nitride pin tools; mechanical properties of the welded joints were determined and the effect of post-weld tempering was investigated. The grades tested were L80 (0.32%C, 0.35%Si, 1.2%Mn, 1.3%Cr, 0.2%Ni, 0.65%Mo) and X70 (0.09%C, 1.45%Mn, 0.5%Ni). Thermocouples were employed to monitor the temperature in the stir zone and HAZ during FSW. Weld mechanical properties were characterised by microhardness profile measurements, tensile tests and Charpy impact tests. Issues discussed include L80 stir zone toughening by post-weld tempering and pin tool mushrooming effects. Finite element modelling was used to model pin deformation and to examine the factors affecting it.

6th International Symposium, 10-13 Oct 2006, Session 10A: FSW of Steels, Paper 02