Development of high strength Ir based tool for friction stir welding

Although several studies on the friction stir welding of high temperature materials have been reported, their practical use has been delayed when compared with soft and relatively low melting point metals such as aluminum, because there have been no tool materials suitable for welding for high temperature materials until recently. The welding tools for these materials are required to have a high performance at elevated temperatures. The purpose of this study is to strengthen iridium (Ir) with an excellent oxidation resistance at elevated temperatures and to develop a welding tool for high temperature materials. As a result, it was clarified that Ir alloys are strengthened by addition of elements with a larger atomic radius than that of Ir. Moreover, the Ir alloy with such added elements showed excellent mechanical properties and oxidation resistance at elevated temperatures. The welding tool made from this alloy was little worn even if SUS304 stainless steel was friction stir welded.