High Integrity Forgings of Aluminum and Titanium Alloys.

摘要

The primary objective of this program was to establish the mechanical property and economic advantage of precision aluminum alloy and titanium alloy aerospace structural forging. The mechanical and fracture properties of the aluminum precision forging were comparable to the aluminum die forgings except at rib flange intersects where highly distorted grain flow and possible defects caused lower fatigue properties. These effects could probably be eliminated by changes in die design and/or preform design. The titanium portion of the program was redirected to the use of titanium castings instead of isothermal precision titanium forgings. This was done because (1) the calculated minimum web thickness was 0.185 in. and the 0.05- to 0.07-in. thickness per drawing could not be achieved, which would require 100% machining, minimizing the potential cost savings; (2) the knockout system was not adequate and would require modification to replace the single knockout system with two knockout stems. The titanium casting though comparable in static strength to conventional titanium die forgings had less than 10% of the fatigue life of the forging. Other design concepts may have improved the fatigue performance. The hourly charges for machining both the aluminum and titanium forgings and castings are provided. (Author)