C. Swallow, K. Slattery, Boeing Phantom Works, St. Louis, MO; G. A. Tomchik, T. G. Dunder, Boeing - 787 Airplane Integration, Seattle, WA; D. G. Sanders, The Boeing Company, Seattle, WA; S. Houston, Cyril Bath, Monroe, NC; R. Pincoski, Dunkirk Specialty Steel, Dunkirk, NY
The growing use of composites in transport aircraft has led to the use of titanium in components that were previously aluminum. These components were typically extruded shapes that were formed to the contour of the aircraft at room temperature in the solution annealed and quenched condition. The high room temperature strength of titanium does not lend itself to being formed at room temperatures. Modifications have been made to existing stretch forming machines allowing parts to be heated before and during stretch forming. Challenges include induced residual stresses during cool-down and differences in coefficients of thermal expansion between the tooling and the work piece. Studies were also performed on hot roll forming titanium plate to shape for subsequent hot stretch forming in lieu of extruding due to the higher mechanical properties which can be achieved.
Summary: The growing use of composites in transport aircraft has led to the use of titanium in components that were previously aluminum. These components were typically extruded shapes that were formed to the contour of the aircraft at room temperature in the solution annealed and quenched condition. The high room temperature strength of titanium does not lend itself to being formed at room temperatures. Modifications have been made to existing stretch forming machines allowing parts to be heated before and during stretch forming. Challenges include induced residual stresses during cool-down and differences in coefficients of thermal expansion between the tooling and the work piece. Studies were also performed on hot roll forming titanium plate to shape for subsequent hot stretch forming in lieu of extruding due to the higher mechanical properties which can be achieved.
