Application of the Hydrostatic Extrusion Process Toward Production of 3AL-2.5V Titanium Alloy Hydraulic Tubing

The subject matter for this paper deviates slightly from that of the SAE symposium, that is “Criteria for current and advanced aircraft hydraulic tubing.” Rather, this paper introduces an entirely new concept for manufacture of hydraulic tubing to satisfy the criteria, with resulting properties and characteristics equal to or superior to those currently available. In addition, it is indicated that the process potentially can manufacture such tubing at substantially lower cost.

The concept of hydrostatic extrusion is based upon the phenomena associated with plasticity of metals under high pressure and in layman's terms is a substitution of pressure for temperature in the forming of metals and metal alloys. Metalworking under pressure is not necessarily a new technology; however, the application of this technology toward the production of tubing is new. It is indicated that the process will yield tubing with improved ductility, higher strength, small grain size, and optimum grain structure. By proper choice of the amount of cold work and thermal treatment after hydrostatic extrusion, a wide range of properties can be reproducibly obtained--in all instances, such properties exceed those of contemporary specification requirements.