Joint properties of ultra thin 430M2 ferritic stainless steel sheets by friction stir welding using pinless tool

In this study, friction stir butt welding of ultra thin 430M2 ferritic stainless steel sheets with satisfactory joint properties has been achieved using a pinless WC-Co tool. Friction stir welding was carried out at a tool rotational speed of 900 rpm and a travel speed of 96 mm/min. FSW joints were welded completely without any unwelded zone resulting from smooth material flow, despite of being adopted pinless tool. It was revealed that the maximum tensile strength of FSW welds was 468 MPa, equivalent to the tensile strength of base metal. Notably, it was found that sigma phase formation in FSW welds is suppressed compared with that of arc welds, resulting in improving joint strength. These results suggest that the low input process of FSW is an effective substitute for the conventional fusion welding GTAW in ultra thin ferritic stainless steel plate.