Even though, FSW process was effective in fabricating joints of alloys of Mg, Al, steel and several metal matrix composites, investigations being carried out on Cu and its alloys is minimal and only insufficient experimental findings are available with respect to mechanical properties and characteristics of micro-structures arising during the welding of alloys of Cu by applying FSW process, which demands us an inevitable need for such objective oriented experimental investigations. This book focuses to provide a better understanding about the suitable conditions (parameters) to be adopted during FSW of alloys of Cu (especially CDA 101 Alloy), the transitions occurring in micro-structural characteristic features, improvements in mechanical properties, the interdependency between the mechanical properties and transformed micro-structures etc. in a better manner. In this book, during the joining of flat plates of Cu alloy namely CDA 101, by employing the process of FSW, a detailed investigation was carried out to understand the impact of the speed of traverse of tool (with cylindrically tapered pin geometry) on the micro-structural characteristics and mechanical properties.