High speed-high quality friction stir welding of austenitic stainless steel

Abstract

Although several studies on the friction stir welding of high temperature materials have recently been reported, their practical use has not yet occurred due to some problems to be solved such as decreases in the corrosion resistance and joint efficiency during a high-speed joining. In this study, the effect of the welding speed on the joint efficiency was investigated in detail. As a result, it has been clarified that at a rotational speed of 600 rpm, the friction stir welding of 304 austenitic stainless steel is possible up to the joining speed of 1 200 mm/min, and the tensile strength of the joint exceeds that of the parent material up to the joining speed of 1 150 mm/min. In addition, the corrosion resistance is significantly improved at the higher welding speeds. No rust was observed during the salt spray testing of the 1 000 mm/min joint. Thus, an increase in the welding speed can improve productivity and the product quality by decreasing corroded region. These results are expected to extend to an actual application to products by further improving the technology. © 2009 ISIJ.