Laser forming near shapes in titanium

Abstract

A new collaborative program sponsored by the DoD Advanced Research Projects Agency (ARPA) and the Office of Naval Research (ONR) has been initiated. The program’s goals are to develop and demonstrate a laser based, rapid prototyping system for titanium and its alloys. Titanium (and alloy) near shapes have been formed from economical precursor metal powders such as raw, sieved titanium Kroll fines and titanium fines blended with elemental alloying powders. In preliminary tests, the sequential laser fusion of thin, laminar metal-powder layers to form integral, 100 percent dense structures has been demonstrated. A 14 Kw CO2 CW high-energy laser was used to form titanium bars and a 4-inch diameter (1-inch wall) cylinder. The laser forming operation was performed in a special argon swept atmosphere control chamber that remained below 30 ppm oxygen during operations. Materials characterization tests showed excellent chemistry control, and mechanical properties exceeding American Society for Testing Materials (ASTM) specifications for C-2 titanium. Economic projections for titanium parts formed in a dedicated laser forming system using the operational parameters developed show cost advantages over cast and forged structures. The process appears advantageous for hard to cast, forge, or form metals such as titanium, niobium, composites, and others; both in time to delivery and final article cost. The process appears well suited for the laser forming of large, near-shape structures directly from metal powders and elemental alloy mixtures without using molds or dies, by the direct download and postprocessing of electronic part descriptions. Further work is planned.A new collaborative program sponsored by the DoD Advanced Research Projects Agency (ARPA) and the Office of Naval Research (ONR) has been initiated. The program’s goals are to develop and demonstrate a laser based, rapid prototyping system for titanium and its alloys. Titanium (and alloy) near shapes have been formed from economical precursor metal powders such as raw, sieved titanium Kroll fines and titanium fines blended with elemental alloying powders. In preliminary tests, the sequential laser fusion of thin, laminar metal-powder layers to form integral, 100 percent dense structures has been demonstrated. A 14 Kw CO2 CW high-energy laser was used to form titanium bars and a 4-inch diameter (1-inch wall) cylinder. The laser forming operation was performed in a special argon swept atmosphere control chamber that remained below 30 ppm oxygen during operations. Materials characterization tests showed excellent chemistry control, and mechanical properties exceeding American Society for Testing Materials (A...