Study on material flow during friction stir welding of aluminum alloy by numerical simulation

摘要

Friction stir welding (FSW) was invented about two decades ago. The solid-state material was mixed by a rigid rotating tool during FSW, so that severe plastic flow occurred during the process. The material flow pattern inside the material was important for producing the weld. However, the material flow was difficult to study by experiments. In this work, the material flow pattern was simulated by using a Computational Solid Mechanics (CSM) method. The heat generation due to both friction and plastic deformation was considered. The flow stress of solid state material measured by experiments was adopted in the numerical model. The three-dimensional temperature distribution and material flow pattern was simulated. The simulated temperature distribution and positions of the marker material agreed well with the experimental results. It could be found that material on the advancing side before welding trended to have more complex flow path than that on the retreating side. This might explain the phenomena that defects during FSW were easier to generate in the advancing side.