Friction stir welding of an aluminum coal hopper railcar

The friction Stir welding (FSW) process was used to fabricate a subscale section of an aluminum railcar designed to ship coal. Coal comprises approximately forty percent by weight of all freight shipped by rail in the United States. The primary mode of transport is via open-top hopper car. Traditional joining techniques for this type of vehicle include bolting, riveting and fusion welding. An analysis was performed to evaluate the cost effectiveness of FSW as a joining process. Key elements of the analysis included materials selection and availability, preliminary static properties, manufacturability and life-cycle cost benefits analysis. Result of this analysis demonstrated a potential cost savings of 20 percent per hopper structure while integrating with the existing rolling chassis and maintaining durability of the basic coal hopper design. The successful fabrication of a subscale prototype demonstrated overall feasibility of the concept and generated valuable data concerning joint and fixturing and tooling requirements.