Chapter 2: Aerospace Materials Characteristics

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Ti‐6Al‐2Sn‐2Zr‐2Mo‐2Cr Alloy for High Strength Aerospace Fasteners

Next generation demanding aerospace systems requirements are pushing the titanium alloy performance needs beyond the upper limits of the workhorse alloy Ti 6Al-4V (Ti 6-4), necessitating the use of advanced solutions. This paper provides an overview of Arconic’s lightweight solution to address the needs of future aerospace fastening systems. The key attributes for aerospace fasteners are strength (tensile, double shear, and fatigue) and manufacturability (ability to forge heads and roll threads while meeting metallurgical and dimensional requirements) at an affordable cost. In particular, increasing double shear strength (DSS) while meeting other requirements is very challenging. Typically, DSS is about 60% of the tensile strength for Ti 6-4, restricting Ti applications to moderate strength levels. Limited deep hardenability of Ti 6-4 (≤0.5”) also restricts the usage to smaller diameter fasteners. Beta Ti alloys (e.g. Beta C) capable of achieving high tensile strengths suffer from shortfalls in DSS and producibility. There is a need for an affordable high strength Ti alloy that can extend titanium fastener usage to higher strength levels and larger size (up to 1”), which will enable reduction in number of joints and weight reductions by replacing higher density nickel/steel fasteners. Ti 6Al-2Sn-2Zr-2Cr-2Mo (Ti 6-22-22), a judiciously balanced α + β Ti alloy, designed and developed by RMI Titanium Company in the early 1970s for thick-section aerospace structural applications with a need for higher strengths than Ti 6-4, is capable of meeting demanding fastener requirements of next generation aerospace systems. Superior producibility and ability to tailor processing-microstructure-property relationships in Ti 6-22-22 for achieving performance improvements will be discussed in this paper

Superior Oxidation Resistance Titanium Alloy ARCONIC-THOR

Next generation fuel-efficient jet engines are running hotter presenting a structural challenge for the exhaust systems and structures adjacent to the engines. A conventional and affordable titanium alloy with superior oxidation resistance provides significant weight reductions and associated cost savings by eliminating the need for high density material systems such as nickel-base superalloys for service temperatures in between current titanium and nickel, enabling major technology advancement in high temperature aerospace applications. This paper presents an overview of Arconic’s engineered material ARCONIC-THORTM to address the needs of future aerospace systems

Integrated Computational Materials Engineering of Gamma Titanium Aluminides for Aerospace Applications

Although the benefits of titanium aluminides for intermediate service temperature applications were well conceived and significant research and development activities were conducted in the past four decades, they remained as developmental materials due to barriers associated with melting, processing, scale-up, and cost. Demanding requirements of efficient aero-engines and extensive risk reduction demonstrations paved the path for commercial introduction of gamma titanium aluminides. The single most attractive current application is for low pressure turbine blades (LPTBs) in advanced aero-engines replacing conventionally cast nickel superalloys. This paper provides an overview of recent progress, producibility challenges, and opportunities. The successful journey of gamma (γ) TiAl LPTB development from laboratory demonstrations to production insertions in mass-produced commercial jet engines will be described. Collaboration and integrated product development were identified as the most critical needs for rapid maturation and implementation of γ-TiAl into aerospace applications. An integrated computational materials engineering modeling framework and toolsets developed under a collaborative US Air Force Metals Affordability Initiative project between industry, government, and academia will be illustrated. Model-based optimization of material and processing for achieving desired performance goals will be highlighted

Integrated Computational Materials Engineering of Gamma Titanium Aluminides for Aerospace Applications

Although the benefits of titanium aluminides for intermediate service temperature applications were well conceived and significant research and development activities were conducted in the past four decades, they remained as developmental materials due to barriers associated with melting, processing, scale-up, and cost. Demanding requirements of efficient aero-engines and extensive risk reduction demonstrations paved the path for commercial introduction of gamma titanium aluminides. The single most attractive current application is for low pressure turbine blades (LPTBs) in advanced aero-engines replacing conventionally cast nickel superalloys. This paper provides an overview of recent progress, producibility challenges, and opportunities. The successful journey of gamma (γ) TiAl LPTB development from laboratory demonstrations to production insertions in mass-produced commercial jet engines will be described. Collaboration and integrated product development were identified as the most critical needs for rapid maturation and implementation of γ-TiAl into aerospace applications. An integrated computational materials engineering modeling framework and toolsets developed under a collaborative US Air Force Metals Affordability Initiative project between industry, government, and academia will be illustrated. Model-based optimization of material and processing for achieving desired performance goals will be highlighted