A Filled Billet Extrusion Process for Production of Tapered Titanium Structural Members.

摘要

This is a manufacturing methods program in which tapered Ti-6Al-4V alloy T and Z shapes were successfully produced by the 'filled billet'technique. The optimum billet design consisted of tapered and warm formed titanium alloy plate sections and solid steel fillers. Billets were generally processed at 1600F to 1700F and 15:1reduction. The extruded shapes exhibited surface finishes of 30to 60RMS. Bonding of the various titanium alloy plate sections was accomplished directly in the extrusion process,and subsequent diffusion heat treatments were not required. Dimensional control of the taper in the extruded shapes was excellent for T shapes and good for Z shapes. The use of titanium alloy preforms machined from bar stock and/or the use of iron or steel powder as a filler material resulted in an inferior product. Titanium-to-titanium bonding was obtained on billets processed at 1600F and above,at extrusion reductions of 9times or greater. Iron contamination of the titanium alloy surfaces was not found to be a problem. Processing at 1850F,above the beta transus,lead to extreme surface roughness in the final extrusion. (Author)