SST Technology Follow-On Program-Phase ⅡnDEVELOPMENT OF IMPROVED TITANIUM 6AL-4V MILL PRODUCTS

摘要

In the SST prototype program, wide variations in mechanical and fracture properties of Ti-6Al-4V mill products were found. During DOT/SST Phase I follow-on work, these variations were shown to be related to composition, crystallographic texture, and microstructure. The Phase II follow-on program applied this technology as a basis to develop new material specifications for high toughness Ti-6Al-4V material. Specifications were prepared for sheet, plate, extrusions, bar, and forgings. The specifications emphasized tighter controls on composition, crystallographic texture, and microstructure, as well as minimum requirements for stress corrosion resistance. Verification testing was conducted on mill products procured to the requirements of the new specifications. The materials exhibited excellent fracture characteristics, with slight loss in tensile strength. Minor modifications to the specifications were incorporated as a result of verification test data. (Author)