Traditional welding techniques require melting material and can cause the growth of precipitate particles in the heat-affected zone, which drastically reduces strength. Friction stir welding, which requires only the brief softening of the alloy, is much less problematic.

Rail remains one of the fastest and safest ways to travel; however, companies looking to make their railcars safer have turned to friction stir welding. One of the most striking successes in the use of FSW is its suitability for successfully making long, butt seam welds in aluminum railway carriages. Friction stir welded panels are stronger, higher quality, and last longer. These panels are also more cost effective to produce. They often yield more consistent results. Using the modern way to produce passenger rail cars the whole body shell can be made from either single wall or hollow double skin extrusions. This design can enhance the crash worthiness of a car and make the vehicle more stable.