Friction Stir Welding (FSW) of Littoral Combat Ship Deckhouse Structure

Abstract

The US Navy's Littoral Combat Ship (LCS) represents a new direction in military capabilities and ship design. The LCS's aluminum superstructure and deckhouse reduces weight and lowers the center of gravity of the ship. Arc welding aluminum is subject to distortion requiring no value straightening activities to be used. Friction stir welding (FSW), a welding process invented in 1991 at TWI in the United Kingdom, is a solid-state welding process that has considerably less weld distortion. It results in more affordable fabrication and inspection of the butt joint weld root. Details of the FSW process development, certification, and fabrication of the LCS superstructure and deck house are described. Experience with FSW on the LCS has resulted in a number of new fabrication ideas and concepts to improve affordability of future LCS and other aluminum ship structures.