ABSTRACT

In 2003 AnsaldoBreda, a Finmeccanica company operating in the rail vehicle transportation sector, and Centro Sviluppo Materiali, an industrial research center, started to investigate the possibility to apply laser technology to replace resistance spot welding process for stiffeners assembly on rail vehicle side panels. Goals of the activities were: • to increase the aesthetics of the car body by eliminating visible indentation on the surface; • to increase flatness of the skin reducing welding deformations; • to increase welding productivity and quality in terms of soundness and repeatability. The weld quality was assessed by metallurgical investigations and mechanical tests such as: hardness profiles, tensile and fatigue tests. The obtained results were compared with strength and fatigue behavior of spot welded joints. Finally, by using optimized and qualified welding procedures, the real components were manufactured obtaining high quality and productivity levels (welding speed up to 5 m/min). Afterwards AnsaldoBreda started to manufacture, committed by the Los Angeles County Metropolitan Transportation Authority, fifty Light Rail Vehicle trams for the Californian city using the new assembly technology and the manufacturing facilities available at Centro Sviluppo Materiali.