Optimization of Blended-Elemental Powder-Based Titanium Alloy Extrusions for Aerospace Applications

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Vol. 44; no. 2; pp. 899 - 910
• Main Authors: El-Soudani, Sami M., Yu, Kuang-O., Crist, Ernie M., Sun, Fusheng, Campbell, Michael B., Esposito, Tony S., Phillips, Joshua J., Moxson, Vladimir, Duz, Vlad A.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.02.2013; Springer; Springer Nature B.V
• Subjects: Aerospace engineering; Applied sciences; Characterization and Evaluation of Materials; Chemistry and Materials Science; Corrosion resistance; Exact sciences and technology; Materials Science; Mechanical properties; Metallic Materials; Metals. Metallurgy; Nanotechnology; Powder metallurgy; Sintering; Structural Materials; Surfaces and Interfaces; Thin Films; Titanium alloys; Cold Isostatic Pressing; Titanium Hydride Powder; Fatigue Crack Growth Rate; Titanium Hydride; Beta Transus; Forming; Spinning; Aeronautic industry; Application; Aerospace industry
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-012-1437-5

The process of canless extrusion in ambient environment, using cold isostatic pressed, and vacuum-sintered, direct-consolidated blended-elemental hydrided ADMA titanium powder, mixed with master alloy powder for the Ti-6Al-4V composition, has been successfully demonstrated. However, these initially processed unoptimized powder-based extrusions also exhibited oxygen content of about 3000 ppm, within the ASTM B817 Standard, but exceeding the AMS Specification 4935 maximum limit of 2000 ppm, and with pre-extrusion residual hydrogen within 300–500 ppm resulting in post-extrusion void nucleation aligned with the extrusion direction. Additional optimization of extrusion billets during the CIP-and-sintering steps has been successfully demonstrated reducing both oxygen and hydrogen contents to levels at or below the AMS Specification limits for Ti-6Al-4V composition (oxygen content of 2000 ppm maximum, and hydrogen content of 125 ppm maximum). Processing-microstructure-property correlations of the optimized, AMS-4935-Specification-conformant, Ti-6Al-4V blended-elemental powder-based product form exhibited an overall mechanical property balance matching that of double-arc-remelted ingot-based extrusions. Property matching was not only in terms of static mechanical properties (room-temperature tensile properties, and monotonic fracture toughness K IC ( K Q ) values), but also in terms of dynamic fatigue properties (combined S / N plus da / dN properties), as well as stress-corrosion resistance, as measured in terms of K ISCC threshold values.