Development of net shape structural titanium manufacturing capability using the system of systems design approach
When attempting to extrude from alpha-beta titanium alloys, the dimensional control and surface quality often do not align with requirements of a machined component. The performance degrades as the thickness of the attempted extrusion shape is reduced to closer to a final thickness. A number of factors influence this behavior and include: lubrication, thermal effects, deformation rates, and strain concentrators. As a result, it is common to require extrusions to be machined into a final component resulting in material losses and costs associated with machining. In order to alleviate this challenge a roller reduction system, for finishing the extrusion down to “machined like” thickness and surface quality, was developed. A design strategy was employed that aligned the machine architecture to the product needs and material behaviors of titanium. Titanium material behaviors were considered in the system design including: shear banding, crystallographic texture, strain induced porosity, cracking, surface galling, rapid surface cooling, and surface layer development. A study of processing parameters was performed to characterize material response to processing temperature and rolling rate. This system was used to produce a T shaped titanium extrusion down to thicknesses and surface quality commensurate with a finished component. The validation of the processes impact on material properties was also studied and verified that wrought material properties can be met.