TWI

A detailed experimental and theoretical investigation was made of the use of friction stir welding (FSP) to modify the microstructure of magnesium AM50 die castings. Rectangular die cast plates of 3 mm thickness of AM50 (Mg, 4.9%Al, 0.39%Mn) were subjected to FSP at speeds between 28 and 30 mm/min. Microstructure and thermal measurements were made at different positions from the weld centre. Microstructure ahead of the FSP tool was investigated using a stop-action method. Optical and SEM methods were used and microstructure details are presented as a function of welding travel speed and distance from weld. An existing computational fluid dynamics model developed for FSW of wrought aluminium alloys was adapted to predict thermal history during FSP of the AM50 dies. Experimental results were compared with process and microstructural models, which were developed to predict the effect of FSP on the material flow, thermal history and microstructural evolution.

8th International Symposium, 18-20 May 2010, Session 2B: FSW & FSP of Magnesium, Paper 01