Approach to plastic deformation and strain rate in FSW process

Abstract

In this work, two simple models to calculate the strain rate at which material deforms during the friction stir welding (FSW) process are proposed. In both cases, predictions are associated with operational parameters such as rotational and travel speed and tool pin radius. A first model is based on the analysis of the strain experienced by the material on the periphery of the pin associated with the rotation and displacement present during the joining process. The second one is based on the resemblance of FSW with an asymmetric rolling process in which a dramatic strain gradient takes place. Using these models, and employing fitting parameters, it is possible to estimate the mean deformation rate during the FSW process. Very reasonable values, which fall in the range of strain rate data reported in the literature, are obtained. This new view should allow determining equivalent experimental conditions (strain, strain rate, and temperature in conventional uniaxial tests) under which this joining process occurs. This is critical to predict weld quality.