The study investigates mechanical properties and microstructure effect for 5086 aluminum alloy with different welding speed of friction stir welding. The 5086 aluminum alloy has good corrosion resistance and welding quality, which often used in the construction of the ship, shipping industry and places that contain some rich-salt regions. Now when we use aluminum alloy to build equipment of ship, there are many factors to consider, for example, the cost of production, the portion of working parts and the limitation of working environment. Therefore, we usually use gas tungsten arc welding（GTAW）and inert gas metal arc welding（GMAW）to proceed the operation of welding. But the input heat affected the properties of base metal and induced the welding defects for the both of welding methods. In order to acquire the welding workpiece with higher quality, we investigate the influence of mechanical properties with different welding speed for FSW, and then select the proper welding speed for Al maternal and ensure the quality of welding parts.
Firstly, the welding process is employed with different welding speeds for the workpiece, and then X-ray is used to examine the welding quality. Based on the tensile experiment, metallographic observation, hardness measurement and fractography analysis of tensile test, after welding the FSW with different welding speeds for 5086 AL alloy is investigated. This study is then conducted on the variation of the mechanical properties and microstructure of the workpiece of welded nugget, the thermo mechanically affected zone（TMAZ）, the heat affected zone（HAZ）and the base material.
Based on the results of experiment, the less petal-pattern materials are spilled in two side edge of welding path, the less defects are occurred. And the distribution of hardness on the cross-section of welding path is U-shape. The minimum hardness occurs between HAZ and TMAZ. And the hardness in the nugget region is higher than those in the HAZ. But the hardness in the nugget region is lower than the base metal. The SEM is employed to observe the fractography of tensile for each experiment, the fracture with dimple structure is ductile failure.