Applicazione della tecnologia SPF-DB (Superplastic Forming - Diffusion Bonding) su componenti aeronautici in lega di titanio Ti-6Al-4V

摘要

Since 1990 the Super Plastic Forming Diffusion Bonding (SPF/DB) process is used by Alenia (Aircraft division) to produce primary structural components made of(Ti6Al4V) alloys. This technology is currently considered strategic in the manufacturing of parts having elevated requisites of rigidity and lightness. The superplastic forming allows to achieve complex geometries with saving of weight and reduction of the phases of moulding and of the assembly operations. The super plastic behaviour and the metallurgical phenomena regarding the diffusion bonding, are here analized. The material characteristics at the basis of the process, are investigated pointing out the main parameters and their influence. Besides, the paper contains a description of the technological SPF-DB process, taking into account the Alenia experience, carried out on two sheets and using the two step technique with particular regard to the facilities and the preliminary operations for the SPF-DB process, that are critical to prevent the typical defectology. It is here also described the laboratory tests and the operations aimed to the acceptability of the components in production phase, explaining the philosophy of choice of such techniques of control.