L. D. Hefti, The Boeing Company, Seattle, WA
This paper will discuss some of the advances that have been made at The Boeing Company to manufacture Superplastically Formed and Diffusion Bonded (SPF/DB) titanium components for aerospace applications. Even though SPF/DB has been in production for over twenty years, challenges have been encountered that need solutions before the process can see wide spread acceptance. Aerospace engineers, designers and stress analysts, need to be assured that the process will yield quality hardware that meets structural requirements. However, the engineers must have requirements that are realistic. For example, if there are areas of the components that can tolerate non-bonds of a certain size and still be structurally acceptable, then the drawing should be zoned accordingly. One of the main concerns is the diffusion bond quality that is achieved and how can this be determined non-destructively. Also of interest is the weight of the part since titanium is being used but may not be necessary to meet loading conditions. A key element of the weight issue is the thickness needed to meet structural requirements. Fortunately, with Finite Element Analysis, the proposed SPF/DB geometry can be modeled and the thicknesses predicted. The weight can then be estimated and a decision made whether steps need to be taken to reduce the weight in order to be competitive with other fabrication technologies. After SPF/DB has been selected as the fabrication method of choice, the hardware needs to be manufactured so that quality is achieved throughout the entire process and the engineering requirements are met.